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Meta-analysis of the effects of indoor nitrogen dioxide and gas cooking on asthma and wheeze in children
Abstract
Since the meta-analysis on the association between indoor nitrogen dioxide (NO2) and childhood respiratory illness in 1992, many new studies have been published. The quantitative effects of indoor NO2 on respiratory illness have not been estimated in a formal meta-analysis since then. We aimed to quantify the association of indoor NO2 and its main source (gas cooking) with childhood asthma and wheeze.
We extracted the association between indoor NO2 (and gas cooking) and childhood asthma and wheeze from population studies published up to 31 March 2013. Data were analysed by inverse-variance-weighted, random-effects meta-analysis. Sensitivity analyses were conducted for different strata. Publication bias and heterogeneity between studies were investigated.
A total of 41 studies met the inclusion criteria. The summary odds ratio from random effects meta-analysis for asthma and gas cooking exposure was 1.32 [95% confidential interval (CI) 1.18-1.48], and for a 15-ppb increase in NO2 it was 1.09 (95% CI 0.91-1.31). Indoor NO2 was associated with current wheeze (random effects OR 1.15; 95% CI 1.06-1.25). The estimates did not vary much with age or between regions. There was no evidence of publication bias.
This meta-analysis provides quantitative evidence that, in children, gas cooking increases the risk of asthma and indoor NO2 increases the risk of current wheeze.
... By these standards, the evidence for causality between NO 2 exposure and asthma is very strong. We have 1) direct evidence: controlled laboratory studies have consistently observed adverse respiratory effects in human asthmatics when inhaling NO 2 for short time periods compared with control groups [23] and observational studies consistently find associations between NO 2 and pediatric asthma on a population level, both outdoors and indoors [5][6][7][8][9][10][11], [24,25]. ...
... The meta-analysis performed by Lin et al. does find a statistically significant (p < 0.05) association between gas stoves and pediatric asthma [24], so Cox refers to Lin et al.'s concern of residual (i.e., unaddressed) confounding bias [4]. First, we note that many of the studies Lin et al. selected do adjust for likely confounders, such as smoking status. ...
... First, we note that many of the studies Lin et al. selected do adjust for likely confounders, such as smoking status. [24]. Lin et al. note that they "used effect estimates from the included studies which were almost always adjusted for known determinants of childhood asthma" [24]. ...
... Key references cited by Kashtan et al. make clear that they, too, only address association. For example, Lin et al. [7] state that "We extracted the association between indoor NO2 (and gas cooking) and childhood asthma and wheeze from population studies published up to 31 March 2013" (emphasis added). • The associations studied may not exist. ...
... This does not make clear that the claimed "link" (i.e., association) is not significantly different from no effect. Lin et al. [7] further state that "Residual confounding by (unmeasured) factors that are associated with gas cooking might be another explanation for our finding of an association between asthma and gas cooking, but not with indoor NO 2 ." Although they do not believe this is likely, they do not formally test for effects of residual confounding or omitted confounders. ...
... If confidently predicted benefits fail to materialize after assumption-driven policies are implemented (e. g., Henneman et al. [13] note for air pollution that "Multiple studies in the accountability field have found it difficult to attribute significant improvements in air quality or public health attributable to air quality regulations"; and Sproston et al. [14] note that bans of animal antibiotics to prevent increases in antibiotic-resistant human infections were followed by "a continued and sustained increase in many countries" in antibiotic-resistant human infections), the credibility of unverified modeling assumptions and mathematical models as a basis for public policy recommendations may wane. For adverse human health effects currently attributed to gas stoves, it is perhaps not premature to point out that assumption-driven causal claims and recommendations such as those advocated by Kashtan et al. have no known validity and that they disagree with empirical studies finding no significant association between NO 2 from gas stoves and childhood asthma [6][7][8][9]. They provide no sound scientific basis for estimating or managing risks. ...
The use of unverified models for risk estimates and policy recommendations can be highly misleading, as their predictions may not reflect real-world health impacts. For example, a recent article states that NO2 from gas stoves “likely causes ∼50,000 cases of current pediatric asthma from long-term NO2 exposure alone” annually in the United States. This explicitly causal claim, which is contrary to several methodology and review articles published in this journal, among others, reflects both (a) An unverified modeling assumption that pediatric asthma burden is approximately proportional to NO2; and (b) An unverified causal assumption that the assumed proportionality between exposure and response is causal. The article is devoid of any causal analysis showing that these assumptions are likely to be true. It does not show that reducing NO2 exposure from gas stoves would reduce pediatric asthma risk. Its key references report no significant associations – let alone causation – between NO2 and pediatric asthma. Thus, the underlying data suggests that the number of pediatric asthma cases caused by gas stoves in the United States is indistinguishable from zero. This highlights the need to rigorously validate modeling assumptions and causal claims in public health risk assessments to ensure scientifically sound foundations for policy decisions.
... A large body of research on the detrimental health effects of exposure to air pollution from all sources provides strong evidence that long-term exposure to ambient PM 2.5, ambient ozone, and household air pollution contributes to premature mortality and increased risk of illness from five chronic noncommunicable diseases: ischemic heart disease, stroke, chronic obstructive pulmonary disease (COPD), lung cancer, and type 2 diabetes; and one group of communicable diseases: lower respiratory infections (LRIs), such as pneumonia (Health Effects Institute, 2020). Evidence also exists of an association between household air pollution and increased asthma exacerbation, particularly if using gas for cooking or heating [e.g., Lee et al. (2020) and Lin et al. (2013)]; however, that evidence has been deemed insufficient regarding asthma development (Health Effects Institute, 2020). 14 Additionally, evidence is growing on the association between long-term exposure to air pollution and adverse birth outcomes (low birthweight, preterm birth, and still birth) (Health Effects Institute, 2020; Lee et al., 2020), as well as neurodevelopmental and neurocognitive outcomes, including cognitive decline (Clifford et al., 2016;Schroeder, 2011;Zare Sakhvidi et al., 2022), chronic kidney disease (Tsai et al., 2021), and gastrointestinal inflammatory diseases (Kaplan et al., 2010;Salim et al., 2014). ...
... Heinrich concluded that results for asthma (onset and exacerbation) and other respiratory endpoints, including lung function, were inconsistent, but as a precaution, recommended extensive use of ventilation when cooking with gas appliances. Lin et al. (2013) conducted a meta-analysis on effects of indoor NO 2 and gas cooking (without other combustion sources) on incidence or prevalence of asthma and wheeze in children. Their analysis showed that gas cooking was associated with asthma (summary OR = 1.32, 95% CI 1.18-1.48) ...
... According to Heinrich (2011), "the most consistent finding for an induction of asthma in childhood is related to exposure to environmental tobacco smoke, to living in homes close to busy roads, and in damp homes where are visible molds at home." -Leonarte et al. (2009) reviewed literature on indoor air pollution and children's respiratory health and found that most studies in developed countries reported detrimental effects of indoor gas combustion on cough/wheeze but not on respiratory infections. Lin et al. (2013) report results from a previous meta-analysis by Hasselblad et al. which showed a positive association between lower respiratory infections (LRIs) in children (OR=1.18, 95% CI,1.11-1.25) ...
To our knowledge, no comprehensive review of scientific literature addresses the various sources and impacts of indoor residential combustion in the United States. This report aims to fill that gap by documenting the state of research on IRC in the United States, specifically on residential combustion appliances and their relation to four research areas:
(1) Sources of IRC and their prevalence in U.S. homes,
(2) Emission profiles from IRC appliances and their impacts on IAQ,
(3) The contributions of IRC appliances to outdoor air quality and climate change, and
(4) The health impacts from indoor and outdoor exposure to emissions from IRC appliances.
... Nitrogen dioxide and benzene emissions are of particular concern, as typical gas stove use can elevate indoor concentrations of these pollutants above health benchmarks (5,6,8,10,11). Long-term exposure (averaged over a year) to NO 2 has been linked to increased incidence and exacerbation of pediatric asthma (13)(14)(15)(16), incidence and mortality from chronic obstructive pulmonary disease (COPD) (17)(18)(19), and incidences of lung cancer, preterm birth, and diabetes mellitus (20). Given the abundance of gas and propane stoves and the dangers of additional NO 2 exposure generally, quantifying the burden of NO 2 exposures and health outcomes from gas and propane combustion by stoves is needed for assessing public safety. ...
... Second, studies that correlate health outcomes with the presence or absence of a gas stove (rather than with direct pollutant exposure) typically do not capture large differences in housing size and layout, ventilation, or behavior that may substantively affect exposure across groups (23)(24)(25), hindering investigations of health disparities mediated through such factors. Existing meta-analyses calculating odds ratios (ORs) of specific health outcomes associated with gas stoves have relied either on correlations between measured indoor NO 2 concentrations and health outcomes, as opposed to directly quantifying NO 2 exposure, or have used the presence of gas stoves as a proxy for NO 2 exposure (16,26). ...
... We then used well-established epidemiological relationships (26,38) for NO 2 exposure to estimate the excess cases of pediatric asthma and adult mortality attributable to longterm NO 2 exposure from gas and propane stoves. We compare our results against estimates of pediatric asthma burden attributable to gas stoves overall (16). ...
Gas and propane stoves emit nitrogen dioxide (NO 2 ) pollution indoors, but the exposures of different U.S. demographic groups are unknown. We estimate NO 2 exposure and health consequences using emissions and concentration measurements from >100 homes, a room-specific indoor air quality model, epidemiological risk parameters, and statistical sampling of housing characteristics and occupant behavior. Gas and propane stoves increase long-term NO 2 exposure 4.0 parts per billion volume on average across the United States, 75% of the World Health Organization’s exposure guideline. This increased exposure likely causes ~50,000 cases of current pediatric asthma from long-term NO 2 exposure alone. Short-term NO 2 exposure from typical gas stove use frequently exceeds both World Health Organization and U.S. Environmental Protection Agency benchmarks. People living in residences <800 ft ² in size incur four times more long-term NO 2 exposure than people in residences >3000 ft ² in size; American Indian/Alaska Native and Black and Hispanic/Latino households incur 60 and 20% more NO 2 exposure, respectively, than the national average.
... Meta-analyses by (Khreis et al., 2017) and (Gruenwald et al., 2022) of epidemiological studies showed clear relationships with asthma development and have enabled modelling studies estimating the broader population impacts of reducing NO 2 exposures (e.g., (Knibbs et al., 2018;Achakulwisut et al., 2019;Jacobs et al., 2019;Hu et al., 2022). (Lin et al., 2013) synthesized the available literature on gas stove use and found correlations with the two health outcomes they studied, asthma development and wheeze in children. This paper provides a 10-year update to Lin et al, to build on existing dose-response findings through the inclusion of studies published through April 2023 that reported on a broader set of potential adverse health effects like hospitalization, asthma symptoms and medication use. ...
... We grounded the evaluation using literature related to interventions where gas combustion appliances were replaced, or effective engineering controls were implemented, including those where measured NO 2 was taken as the main exposure variable. We grounded the review in the landmark intervention studies conducted in Australia and New Zealand (Pilotto 4 et al., 2004;Howden-Chapman et al., 2008;Marks et al., 2010;Gillespie-Bennett et al., 2011), and a comprehensive meta-analysis focused on gas stove effects on cough and wheeze (Lin et al., 2013). We used Google Scholar to identify works citing these studies. ...
... Two studies considered asthma incidence (Lin et al., 2013;Khreis et al., 2017). Pooled effect estimates and confidence intervals from Kreis and colleagues spanned above one and reached 2.08 (95% CI 1.45-2.94) ...
While a growing body of scientific literature describes the population health impacts of fossil fuel production and burning via climate and air pollution pathways, less is known about the health impacts of indoor combustion. This paper summarizes the results of studies from the last two decades that investigated the association between exposure to sources of unvented combustion pollutants in homes and a range of health outcomes. We found gas combustion to be associated with 6-28% (95% confidence intervals) increased odds of asthma symptoms, 4-51% increased odds of systemic symptoms, 7-81% increased odds of asthma medication use, and 3-12% increased risk of mortality. These findings can be used to improve public health, for example, by informing requirements for improved ventilation and source control, justifying switching to vented appliances, better regulation of device emissions and quantifying the benefits of electrification of end-uses. Dose-response relationships between human health, NO2 exposure, and other by-products of combustion are not characterized with a high degree of precision. However, there is clear evidence of a wide range of health effects, even at low levels of exposure. Despite the various designs, geographic sites, length of follow-up, and study dates, we noted a level of consistency between the studies within the current meta-analysis, and with previous ones, which strengthens the level of confidence in our findings.
... and seven European studies (meta-OR = 1.34, 95% CI: 1.13-1.60) reported in a meta-analysis by Lin et al. [18] of epidemiology studies published between 1977 and 2013, Gruenwald et al. [7] reported that "12.7% (95% CI = 6.3-19.3%) of current childhood asthma in the US is attributable to gas stove use." However, in Gruenwald et al. [7], a series of common mistakes were made in calculating and interpreting this PAF, some, but not all, of which have been pointed out previously [2,13,17]. ...
... In the case of gas cooking exposure and childhood asthma, the meta-OR that the PAF was calculated from was subject to not only publication bias but also biases that were common among the contributing individual studies, primarily due to exposure measurement error, reverse causation, confounding, and selection bias [17]. While Gruenwald et al. [7] calculated 95% CIs of their PAF estimates to account for random variation, they did not address the potential biases in their PAF estimates that were carried over from the meta-risk estimates extracted from Lin et al. [18]. ...
... That is, primarily, the exposure definition and distribution underlying the risk estimate should be the same or sufficiently similar as those underlying the estimated prevalence of exposure, as well as the intended PAF estimate; the health outcome definition underlying the risk estimate should be the same or sufficiently similar as that underlying the intended PAF estimate; and the population characteristics should be sufficiently similar between the study population and the target population [1,3,6,23]. In the case of gas cooking exposure and childhood asthma, Gruenwald et al. [7] extracted North American-and European-specific meta-risk estimates from Lin et al. [18] and further combined them "given the similarities in housing characteristics and gas-stove usage patterns across these geographies." However, as shown in Li et al. [17], the exposure definition (e.g., primarily use gas for cooking vs. ever use gas for cooking vs. presence of gas stove) and distribution (e.g., prevalence being 5.1% vs. 86.5%), ...
... NO 2 irritates the respiratory tract and exacerbates conditions such as asthma, particularly in children, through oxidative stress and inflammatory responses [14]. ...
... A meta-analysis found a 24% increased risk of developing current asthma and 42% increased risk of developing lifetime asthma in children living in homes with gas cooking. Even more, the analysis revealed a 15% increase in current wheeze for the children per 15ppb of NO 2 [14]. NO 2 exposure from gas cooking appliances is estimated to be responsible for approximately 41,000 pediatric asthma cases in the EU and UK [4]. ...
Gas stoves are prevalent in residences worldwide as they are both reliable and economical. However, there is a growing body of evidence that indicates that they emit significant levels of indoor air pollutants, including nitrogen dioxide (NO2), carbon monoxide (CO), volatile organic compounds (VOCs) such as formaldehyde, and particulate matter (PM), which pose serious health risks. Studies demonstrate that hourly average NO2 concentrations in kitchens can exceed 200 μg/m3, surpassing the World Health Organization (WHO) indoor air quality guidelines. Similarly, CO levels can reach above 34 mg/m3, potentially exceeding the WHO guidelines for indoor air quality of 35 mg/m3 over 1 hour. VOCs and PM add to the pollution burden, with indoor formaldehyde concentrations ranging from 0.18 mg/m3 to 0.45 mg/m3 and PM levels reaching over 86 μg/m3 during gas oven use. These emissions may exacerbate respiratory diseases, such as asthma, cardiovascular and neurological health issues. This review consolidates scientific literature on the health impacts of these gas stove pollutants and discusses mitigation strategies that can effectively reduce exposure.
... Over time, medical studies have demonstrated that even minimal concentrations of nitrogen oxides in inhaled air pose significant risks to both human health and the natural environment [1,12,13]. Nitrogen dioxide is highly reactive chemically, making it particularly hazardous to living organisms. ...
... The regulations currently in effect in Poland [18] for premises designated for long-term human occupancy establish permissible concentration limits for only a limited number of harmful substances. However, these regulations do not address nitrogen dioxide, which, as numerous studies indicate, can be generated in concentrations that pose a risk to occupants even during the normal operation of gas stoves [1,12,13]. ...
This article considers issues related to air pollution in residential apartments equipped with gas stoves. The combustion products from gas stoves are released directly into the indoor air, where people can spend a significant part of their time. Even relatively low concentrations of harmful substances contained in combustion products can pose serious health risks and potentially threaten lives. The detrimental effects of nitrogen oxides (NOx) on human health and the environment are briefly analyzed. A comparison and analysis of legal regulations and standards regarding the maximum permissible concentration of NOx in the air across various countries are conducted. Theoretical calculations estimating the potential NOx levels in gas-equipped kitchens are presented. Additionally, the results of experimental studies measuring the NOx concentrations in the air of apartments with different gas stove designs, burner types, and ventilation methods are presented. The authors’ data are compared with existing data from other similar studies.
... It can also appear at high concentrations in kitchens. A systematic review by Lin and colleagues [3] provides strong evidence that using gas for cooking and heating can lead to pollutant levels-such as nitrogen dioxide, carbon monoxide, and PM2.5-that exceed the World Health Organization's indoor air quality guidelines. Particle pollutants vary in size. ...
... 1 ⃝ IV Assumption I (Relevance Assumption): The genetic variant (G) is associated with the exposure (X). 2 ⃝ IV Assumption II (Independence Assumption): The genetic variant (G) is independent of any confounding factors (U). 3 ⃝ IV Assumption III (Exclusivity Assumption): The genetic variant (G) affects the outcome (Y) only through the exposure (X) and not via any other pathways. Assumptions II and III are collectively referred to as being independent of pleiotropy. ...
Air pollutants have both acute and chronic impacts on human health, affecting multiple systems and organs. While PM2.5 exposure is commonly assumed to be strongly associated with all respiratory diseases, this relationship has not been systematically analyzed. This study employed a two-sample Mendelian randomization approach to investigate the effects of PM2.5 on eight common lung diseases, using data from GWAS. Additionally, multivariable Mendelian randomization was applied to assess the direct effects of various air pollutants and the mediating roles of common factors such as BMI and smoking. At a significance threshold of 5×10⁻⁸, PM2.5 showed a significant causal relationship with both asthma and COPD. When the screening threshold was relaxed to 5× 10⁻⁶, this exposure continued to demonstrate significant associations not only with asthma and COPD, but also with other respiratory diseases, including pneumonia, emphysema/chronic bronchitis, and lung cancer. In the multivariable Mendelian randomization analysis, which controlled for smoking and bacterial infections, the association with pneumonia became non-significant, while the relationships with the other four diseases persisted. This study provides a systematic exploration of the relationship between PM2.5 and eight pulmonary diseases from a new perspective, deepening our understanding of the impact of air pollution on health and laying the foundation for future efforts to mitigate these effects.
... There are benefits of transitioning from gas-powered to electric stoves for health and greenhouse gas emission reductions. Switching to clean cooking can lead to health benefits by improving indoor air quality (Jarvis et al., 1996;Kile et al., 2014;Lin et al., 2013;Matte et al., 2024). Conventional electric stoves generate electricity via metal coils that transfer heat to a pan, while induction stoves generate heat more efficiently and quickly directly in iron pans via electromagnetic coils. ...
... Including education about health benefits could provide important and powerful motivation to shift preferences and can be tailored for local communities and contexts. For example, improved indoor air quality stemming from clean cooking (Jarvis et al., 1996;Kile et al., 2014;Lin et al., 2013;Matte et al., 2024) could provide motivation for adoption among families and residents worried about respiratory health. Alleviating energy insecurity may help households as they meet other basic needs, reduce stress, and support a healthier and more comfortable home environment (Hernández, 2023;Siegel et al., 2024). ...
Adoption of electric stoves and rooftop solar can reduce fossil-fuel reliance and improve health by decreasing indoor air pollution and alleviating energy insecurity. This study assessed prevalence and perceptions of these clean-energy technologies to increase adoption in New York City (NYC). A representative survey of 1950 NYC adults was conducted from February 28 to April 1, 2022. Fourteen percent of people had an electric stove; 86% had gas stoves. Black, Latino/a, and lower-income residents were more likely to have electric stoves than White and higher-income residents. Only 14% of residents were interested in switching from gas to electric stoves. Of the 71% with gas stoves uninterested in switching, nearly half (45%) preferred gas cooking, particularly among White and higher-income residents, indicating a large opportunity to shift preferences. About 5% used solar for their home or building; another 77% were interested in solar. Of the 18% uninterested in solar, reasons included lack of agency, confusion about operation, and costs. Education about health and cost benefits, induction technology, how to transition, available subsidies, and other efforts to reduce adoption barriers can support clean technology uptake. Residential clean energy metrics should be tracked regularly to ensure that technology adoption proceeds equitably.
... In light of current evidence that suggests that gas for cooking and heating can potentially affect child asthma and wheezing [10][11][12] and other respiratory health issues 13,14 (through elevated emissions of NO 2 ), 15,16 this Article aims to highlight the state of evidence for these outcomes and provides more robust pooled estimates of effect. ...
... These results provide an important update (additional 27 studies, with 13 studies published since 2013) to the only other metaanalysis of cooking with gas and asthma (which compared gas users to non-users), conducted by Lin and colleagues. 10 The authors reported a 32% increased risk for current and lifetime asthma (OR 1·32, 95% CI 1·18-1·48) on the basis of 19 studies and noted that potential confounding could have exaggerated effects. To investigate the role of confounding in our meta-analyses, sensitivity analyses were done adjusting for key confounders (including active and passive smoking, ambient air pollution (proxies), and socioeconomic status; appendix p 21). ...
... Examples of 'systemic ignorance' (maladaptive responses): Despite there being some evidence [20][21][22] that natural gas cooking can cause human health risk [21], there is a societal response to do nothing. Governments engage in inaction in the face of this uncomfortable knowledge, and individual citizens choose to continue to purchase and install gas cooking despite mounting evidence and the potential risk. ...
... Examples of 'systemic ignorance' (maladaptive responses): Despite there being some evidence [20][21][22] that natural gas cooking can cause human health risk [21], there is a societal response to do nothing. Governments engage in inaction in the face of this uncomfortable knowledge, and individual citizens choose to continue to purchase and install gas cooking despite mounting evidence and the potential risk. ...
Current efforts towards sustainability tend to focus on maintaining existing systems and structures, by relying on reductionist approaches to problem solving. Increasingly, there is a call for more effective action in reaching sustainability, not through reductionism (e.g. solutions which reinforce the status quo), but through transformative societal changes and cultural shifts. Despite these calls, widespread resistance to such changes remains. This work discusses one of the underlying causes, namely maladaptive responses to uncertainty.
Uncertainty impacts nearly every aspect of sustainability transformations within a society. There are uncertainties related to the defining characteristics of sustainability, the complexity of sustainability, and to the changing roles and identities of individuals within a society as they transition to sustainability. Furthermore, the process which is increasingly called upon to address these diverse sources of uncertainty, known as post-normal science, introduces novel sources of uncertainty.
Up to this point, many societies’ responses to this array of sustainability transitions uncertainty is to respond maladaptively, representing uncertainty intolerance (e.g. denial, dismissal, disengagement), as opposed to adaptive responses (e.g. curiosity, acknowledgement and action). Herein, we describe the sources of uncertainty related to sustainable transitions, the role that post-normal science can play in addressing these uncertainties, and describe strategies to support societies’ collective capacity for developing uncertainty tolerance to better engage with the processes required for a sustainable future.
... Research has shown that cooking with natural gas appliances increases indoor air pollution and exposure to PM 2.5 , NO 2 , and CO, and these pollutants are correlated with respiratory illness and other adverse outcomes (Nicole 2014, Holm et al 2018, Zhu et al 2020. The health effects of natural gas appliances have been evaluated using metrics (table 8) including population attributable fractions for childhood asthma and disability-adjusted life years (DALYs, Knibbs et al 2018), as well as estimated risk of current and lifetime asthma (Lin et al 2013). Because low-income and Black children have been documented to experience higher rates of asthma (Pate et al 2021), residential electrification has the potential to positively impact historically disadvantaged communities by reducing exposure to indoor air pollutants. ...
... Another approach is the use of composite indices that designate specific communities as 'disadvantaged' or 'burdened' according to a combination of socioeconomic, health, and environmental factors. Such indices have been developed by the California Environmental Protection Agency for SB 535 (CalEnviroScreen) and the White House for the An Australian study determined a population attributable fraction that associates 12.3% of Australian childhood asthma cases with gas stoves, which corresponds to 2756 disability-adjusted life years (Knibbs et al 2018) A meta-analysis of 42 studies estimated that children exposed to gas cooking had a 32% increased risk of having current and lifetime asthma (Lin et al 2013) There are approximately 2.3 million deaths and 91 million disability-adjusted life years attributed each year to associated household air pollution from solid fuels (Murray et al 2020) Avoided premature mortality Cumulative avoided premature mortalities (#), annual avoided premature mortalities (# year −1 ) ...
A low-carbon energy transition is essential for mitigating climate change but can also cause energy justice and equity impacts on Black, Indigenous, and People of Color (BIPOC), low-income, and other frontline communities. Examples include exacerbating energy burden, inaccessibility and unaffordability of low-carbon energy and electric end-use technologies, property value loss and displacement from renewable energy siting, and unequal health benefits and employment losses from fossil fuel retirement. To avoid perpetuating historical and creating new injustices, an equitable and just energy transition will require careful planning and execution. To this end, measuring and evaluating the effects of existing and proposed programs and policies aimed at decarbonizing energy systems is critical. However, methods and metrics for evaluating equity effects vary across disciplines and transitions, making it challenging to identify effective evaluation strategies. This paper presents a comprehensive review of the equity implications of low-carbon energy transitions and identifies key metrics that have been used across disciplines to quantify energy injustices and equity impacts. We focus on four key low-carbon energy transitions: (1) renewable energy deployment; (2) fossil fuel infrastructure retirement; (3) transportation electrification; and (4) residential building decarbonization. We classify energy justice and equity metrics into the dimensions of Health, Access, and Livelihood, and construct an analytical framework that supports policymakers, planners and other stakeholders in identifying important equity considerations and quantitatively evaluating the effects of decarbonization initiatives. While our framework can serve as a starting point for evaluating justice and equity impacts of energy transitions, further work is needed to address the limitations of existing metrics and additional evaluation methods will be critical to effect energy transitions that are truly equitable.
... Recent research has also documented both the presence of toxic chemicals like volatile organic compounds and benzene in natural gas samples from US homes and substantial leakage of these chemicals even when stoves are not in use (33)(34)(35). Somewhat more limited evidence has directly documented associations between cooking with gas and poor health (36)(37)(38)(39)(40), though studies with strong causal identification are lacking. ...
... To our knowledge, no study has analyzed the health gains from widespread replacement of gas with electricity as we do here, which makes it difficult to compare our work to the existing literature. One meta-analysis of 19 studies concluded that children living in households with gas stoves had a 32% higher risk of having asthma as compared to those living in households with electric stoves (38). Elsewhere, a simulation study estimated that replacing gas stoves would reduce severe asthma attacks by 7% in an urban population (54). ...
Household electrification is thought to be an important part of a carbon-neutral future and could also have additional benefits to adopting households such as improved air quality. However, the effectiveness of specific electrification policies in reducing total emissions and boosting household livelihoods remains a crucial open question in both developed and developing countries. We investigated a transition of more than 750,000 households from gas to electric cookstoves-one of the most popular residential electrification strategies-in Ecuador following a program that promoted induction stoves and assessed its impacts on electricity consumption, greenhouse gas emissions, and health. We estimate that the program resulted in a 5% increase in total residential electricity consumption between 2015 and 2021. By offsetting a commensurate amount of cooking gas combustion, we find that the program likely reduced national greenhouse gas emissions, thanks in part to the country's electricity grid being 80% hydropower in later parts of the time period. Increased induction stove uptake was also associated with declines in all-cause and respiratory-related hospitalizations nationwide. These findings suggest that, when the electricity grid is largely powered by renewables, gas-to-induction cooking transitions represent a promising way of amplifying the health and climate cobenefits of net-carbon-zero policies.
... HAPSF is associated with an increased risk of adverse health effects. There is a growing body of research indicating that household air pollution is closely linked to a range of cardiopulmonary diseases, pediatric conditions, and maternal health issues [3][4][5]. In 2017, household air pollution was estimated to have caused over 1.8 million deaths [6]. ...
Purpose
To explore the global, regional, and country-specific burden of tracheal, bronchus, and lung cancer (TBL) in individuals aged 55 and above due to household air pollution from solid fuels (HAPSF) between 1990 and 2021, and to project its incidence and mortality rates for 2044.
Methods
This study utilized data from the Global Burden of Disease Study 2021 (GBD 2021) to assess the burden of TBL in individuals aged 55 and above due to HAPSF between 1990 and 2021. The Age-Period-Cohort (APC) model, based on Poisson distribution, was used to analyze the impact of age, period, and cohort on TBL mortality trends. Joinpoint regression and decomposition analysis were applied to identify significant changes in trends and assess the contributions of population growth, aging, and epidemiological transitions. Based on the identified trends, projections of TBL incidence and mortality rates for 2044 were made using the Bayesian Age-Period-Cohort (BAPC) model. The analysis was conducted across 204 countries and regions, considering different socio-demographic index (SDI) levels.
Results
In 2021, significant disparities in TBL burden attributable to HAPSF were observed across 204 countries. High-SDI countries like the United Arab Emirates had the lowest TBL-related death and DALY rates, while low-SDI countries, such as North Korea, reported the highest. From 1990 to 2021, global TBL-related DALYs declined by 4.17% annually, with more substantial reductions in high-SDI regions. However, a slight resurgence in DALYs was observed between 2019 and 2021. DALY trends showed variations by age and sex, with more pronounced declines in higher-SDI regions, particularly for older age groups. Projections for 2041 indicate continued substantial decreases in TBL burden across all age groups, with the most significant reductions expected among males. Decomposition analysis revealed that population growth primarily contributed to the increase in TBL burden, while epidemiological transitions led to reductions, especially in middle and high-SDI regions. Frontier analysis identified countries with the greatest potential for improvement in TBL burden, including both low-SDI countries and certain high-SDI regions. Projections using the Bayesian Age-Period-Cohort (BAPC) model suggest that DALYs will decrease substantially by 2044, with the most significant reductions in the 70–74 and 65–69 age groups.
Conclusions
Socioeconomic development is negatively correlated with the TBL burden from HAPSF. Lower SDI countries face a heavier burden, while high SDI countries see increased TBL in aging populations. Tailored policies are needed for different SDI regions.
... In this study, using gas as a fuel for cooking was associated with a decreased probability of wheeze. These findings were unexpected due to several studies that have shown that fumes from gases were a risk factor for asthma and wheeze [60][61][62]. An asthma report also showed that when used as a cooking fuel, gas releases chemicals that induce inflammation of the airways and may lead to asthma exacerbation [63]. ...
Background: The rise of asthma prevalence in recent decades has been attributed to changes in dietary patterns, especially in developing countries. Studies have also suggested that dietary patterns play an important role in both asthma development and management. This study aimed to investigate the association between consumption of various foods and environmental factors with asthma and wheeze among adolescents. Methods: A self-administered standardized International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire was used to collect data on demographics, respiratory health, exposure to air pollution, and diet on n = 2855 adolescents residing in Vhembe District, South Africa. Results: The prevalence of asthma and wheeze were 18.91% and 37.69%, respectively. Consuming various foods such as fast foods (OR = 1.41; 95% CI: 1.06–1.88), bread (OR = 0.60; 95% CI: 0.45–1.81), pasta (OR = 1.39; 95% CI: 1.06–1.84), seafood (OR = 1.79; 95% CI: 0.65–1.24), and nuts (OR = 0.85; 95% CI: 0.65–1.12) were significantly associated with asthma in the crude logistic regression analysis. Further analysis in the multiple regression model indicated a strong association of asthma with consumption of nuts (OR = 1.55; 95% CI: 1.11–2.17), seafood (OR = 1.60; 95% CI: 1.03–2.49), and cereal (OR = 0.67; 95% CI: 0.45–0.99). In relation to wheeze, consumption of meat (red) (OR = 0.77; 95% CI: 0.60–0.99) was a protective factor in the crude analysis. The multiple logistic regression model showed that, seafood (OR = 0.76; 95% CI: 0.59–0.96), fruit (OR = 0.55; 95% CI: 0.32–0.94), nuts (OR = 1.88; 95% CI: 1.50–2.66), and olive oil (OR = 1.48; 95% CI: 1.09–2.00) were significantly associated with wheeze. Conclusion: Diet plays a major role in respiratory health, especially in asthma and wheeze. Dietary changes may play a role in reducing the burden of asthma and other respiratory symptoms in adolescents.
... 48 50 A meta-analysis of 41 epidemiology studies found that indoor NO 2 exposure from gas cooking increased the risk of current asthma symptoms in children. 51 Inhaled NO 2 gas from cooking stoves can cause small airway dysfunction due to their penetration into the peripheral airways. 52 A cross-sectional study in Changsha, China, found a significant positive association between exposure to SO 2 and NO 2 and asthma during preconception and prenatal periods. ...
Background
Household air pollution continues to be a major public health hazard due to the continued use of household fuel sources. Globally, approximately 4 million people die prematurely each year due to exposure to household air pollution sources. Children are more susceptible to health effects associated with air pollution because their immune systems and lungs are not fully developed.
Objective
The objective of the study was to investigate the association between household fuel use and current severe asthma symptoms among preschool children in Gauteng province, South Africa.
Methods
This was a cross-sectional study conducted in the City of Tshwane Metropolitan Municipality in Gauteng province, South Africa. A total of 1844 parents and guardians of preschool children completed the modified International Study of Asthma and Allergies in Childhood questionnaire. However, a total of four questionnaires were discarded due to incorrect completion. Therefore, a total of 1840 questionnaires were included in the data analysis. Data were analysed using multiple logistic regression analysis.
Results
The prevalence of current severe asthma symptoms was 15.4%. The use of gas for cooking or heating significantly increased the likelihood of current severe asthma symptoms among preschool children (OR=3.20;95% CI 2.08 to 4.91; p<0.001). The use of open fire sources (paraffin, wood or coal) increased the likelihood of severe asthma symptoms among preschool children by 87% (95% CI 0.98 to 3.55; p=0.057).
Conclusion
The study observed that using gas and open fire sources for cooking or heating was associated with current severe asthma symptoms among preschool children in Gauteng, South Africa. Household air quality regulations should be developed to mitigate child exposure to household air pollution in the study setting.
... While our results show that the financial and environmental benefits for cooking retrofits are lower than other appliances, recent studies have shown that gas stoves may leak more methane than previously thought in addition to health-related pollutants such as nitrogen oxides and benzene [45,46]. Exposure to the pollutants emitted when cooking with gas can lead to various health risks, including respiratory illnesses and general increased mortality [47,48], with children being especially susceptible to detrimental health outcomes [49][50][51]. ...
Residential and commercial buildings account for 75% of electricity and 40% of the total energy consumption in the United States, costing over $400 billion annually. Electrification and energy efficiency retrofits offer a viable decarbonization pathway, especially since half of US homes were built before modern building codes. These older homes are often occupied by low-to-moderate-income (LMI) families. Equitable electrification provides a unique opportunity to considerably reduce emissions in communities where energy bill savings have the most impact on household finances. This study evaluates how the Inflation Reduction Act (IRA) impacts the adoption potential of air-source heat pumps (ASHPs), heat pump water heaters and clothes dryers, and electric cooking ranges across income groups in the United States. Using a database that statistically represents the US housing stock, we estimate the indicative adoption potential of these technologies under scenarios that represent Pre-IRA conditions and a reference case with IRA provisions. After IRA rebates were introduced, adoption potential for LMI households more than doubled for ASHPs, heat pump water heaters, and electric cooking ranges and more than tripled for heat pump clothes dryers relative to Pre-IRA adoption potential. Cooking retrofits had the lowest adoption potential, and homes that electrified space heating without weatherization had greater adoption potential than those that underwent basic or enhanced enclosure upgrades. Our results show that the introduction of IRA rebates and a gradually decarbonizing grid substantially improves adoption potential for LMI households and even surpasses the adoption potential of middle and upper-income households.
... Gas stoves may pose a greater health risk due to their proximity to individuals and their children and their potential to produce concentrated emissions during cooking activities [28][29][30]. Indoor combustion from gas stoves has been identified as an important source of indoor NO 2 [31][32][33]. During cooking, peaks in NO 2 are generated that may reach hundreds of parts per billion (ppb), exceeding 100 ppb-the outdoor short-term 1 h National Ambient Air Quality Standard (NAAQS)-after only a few minutes [28][29][30]. ...
Nitrogen dioxide (NO2) and particulate matter of 2.5 microns (PM2.5) are air pollutants that impact health, especially among vulnerable populations with respiratory disease. This study identifies factors influencing indoor NO2 and PM2.5 in low-income households of older adults with asthma who use gas stoves in Lowell, Massachusetts. Environmental sampling was conducted in 73 homes, measuring NO2, PM2.5, fractional stove-use, temperature, and humidity for 5–7 days. Participants were recruited between December 2020 and July 2022. Questionnaires were used to collect data on factors influencing indoor NO2 and PM2.5 concentrations. Daily outdoor NO2 and PM2.5 concentrations were obtained from a United States Environmental Protection Agency (EPA) monitoring station. Paired t-tests were conducted between indoor and outdoor NO2 and PM2.5 concentrations, and linear regression was used to evaluate factors influencing indoor NO2 and PM2.5 concentrations. The average indoor concentration for NO2 and PM2.5 were 21.8 (GSD = 2.1) ppb and 16.2 (GSD = 2.7) µg/m³, respectively. Indoor NO2 and PM2.5 concentrations exceeded outdoor concentrations significantly. In multiple regression models, season and pilot light stove use significantly predicted indoor NO2. Season and air freshener use for 6–7 days/week significantly predicted indoor PM2.5. Season-influenced higher indoor concentrations are likely due to reduced ventilation in colder months in the Northeast U.S.
... Both gas cooking and household NO 2 concentrations are thought to contribute to asthma and childhood wheezing [18][19][20]. Studies of school-aged children have reported an association of gas cooking or cooking-related emissions with cough [21], daily NO 2 exposure with nighttime inhaler use [22], and 72-h NO 2 exposure with cough or nighttime symptoms [23]. ...
Background
Cooking-related emissions contribute to air pollutants in the home and may influence children’s health outcomes.
Objective
In this pilot study, we investigate the effects of a cooking ventilation intervention in homes with gas stoves, including a video-based educational intervention and range hood replacement (when needed) in children’s homes.
Methods
This was a pilot (n = 14), before-after trial (clinicaltrials.gov #NCT04464720) in homes in the San Francisco Bay Area that had a school-aged child, a gas stove, and either a venting range hood or over-the-range microwave/hood. Cooking events, ventilation use, and indoor air pollution were measured in homes for 2–4 weeks, and children completed respiratory assessments. Midway, families received this intervention: (1) education about the hazards of cooking-related pollutants and benefits of both switching to back burners and using the range hood whenever cooking and (2) ensuring the range hood met airflow and sound performance standards. The educational intervention was delivered via a video developed in conjunction with local youth.
Results
We found substantially increased use of back burners and slight increases in range hood use during cooking after intervening. Even though there was no change in cooking frequency or duration, these behavior changes resulted in decreases in nitrogen dioxide (NO2), including significant decreases in the total integrated concentration of NO2 over all cooking events from 1230 ppb*min (IQR 336, 7861) to 756 (IQR 84.0, 4210; p < 0.05) and NO2 collected on samplers over the entire pre- and post-intervention intervals from 10.4 ppb (IQR 3.5, 47.5) to 9.4 (IQR 3.0, 36.1; p < 0.005). There were smaller changes in PM2.5, and no changes were seen in respiratory outcomes.
Impact
This pilot before-after trial evaluated the use of a four-minute educational video to improve cooking ventilation in homes with gas stoves and one or more school-aged children. Participant behavior changed after watching the video, and there were decreases in indoor air pollutant concentrations in the home, some of which were significant. This brief video is now publicly available in English and Spanish (wspehsu.ucsf.edu/projects/indoor-air-quality), and this provides suggestive evidence of the utility of this simple intervention, which could be particularly beneficial for households that have children with asthma.
... Among the main pollutants emitted by these stoves due to combustion are carbon monoxide, formaldehyde, and nitrogen dioxide [69]. It has been shown that these pollutants significantly harm human health by increasing the risk of lung diseases such as childhood asthma [70], chronic obstructive pulmonary disease (COPD) [34], and whooping cough [33]. Stoves burning fuels such as wood, coal, kerosene, natural gas, and liquefied petroleum gas also emit methane [71] and benzene [31] directly into the air through leaks and incomplete combustion [71]. ...
Induction stoves are increasingly recognized as the future of cooking technology due to their numerous benefits, including enhanced energy efficiency, improved safety, and precise cooking control. This paper provides a comprehensive review of the key technological advancements in induction stoves, while also examining the societal and health impacts that need to be addressed to support their widespread adoption. Induction stoves operate based on the principle of eddy currents induced in metal cookware, which generate heat directly within the pot, reducing cooking times and increasing energy efficiency compared with conventional gas and electric stoves. Moreover, induction stoves are considered an environmentally sustainable option, as they contribute to improvements in indoor air quality by reducing emissions associated with fuel combustion during cooking. However, ongoing research is essential to ensure the safe and effective use of this technology on a broader scale.
... 20 This finding aligns with established relationships between respiratory health and the use of gas cookers, especially in asthmatics. 21 There is a move in European countries and some US states to legislate against installing gas into new build homes. While this initiative is based on carbon emission reduction, it would also almost entirely remove indoor generated NO 2 and CO from the home environment, leading to potentially Table 3 Average change in peak expiratory flow (PEF) and 95% CI associated with an IQR increase on the same day exposure Results were also presented for those who spent all day at home or not. ...
Introduction
While associations between ambient air pollution and respiratory health in chronic obstructive pulmonary disease (COPD) patients are well studied, little is known about individuals’ personal exposure to pollution and associated health effects by source.
Aim
To separate measured total personal exposure into indoor-generated and outdoor-generated pollution and use these improved metrics in health models for establishing more reliable associations with exacerbations and respiratory symptoms.
Methods
We enrolled a panel of 76 patients with COPD and continuously measured their personal exposure to particles and gaseous pollutants and location with portable monitors for 134 days on average. We collected daily health information related to respiratory symptoms through diary cards and peak expiratory flow (PEF). Mixed-effects models were applied to quantify the relationship between total, indoor-generated and outdoor-generated personal exposures to pollutants with exacerbation and symptoms occurrence and PEF.
Results
Exposure to nitrogen dioxide from both indoor and outdoor sources was associated with exacerbations and respiratory symptoms. We observed an increase of 33% (22%–45%), 19% (12%–18%) and 12% (5%–20%) in the odds of exacerbation for an IQR increase in total, indoor-generated and outdoor-generated exposures. For carbon monoxide, health effects were mainly attributed to indoor-generated pollution. While no associations were observed for particulate matter 2.5 with COPD exacerbations, indoor-generated particles were associated with a significant decrease in PEF.
Conclusions
Indoor-generated and outdoor-generated pollution can deteriorate COPD patients’ health. Policy-makers, physicians and patients with COPD should note the importance of decreasing exposure equally to both source types to decrease risk of exacerbation.
... The household air pollution reflects the vulnerability from ambient environmental risk factors, associated with increased mortality and disease burden, particularly in low-and middle-income countries (Azam et al., 2023;Lee et al., 2020;Lv et al., 2021). To measure household air pollution, we use data on households that cook with polluting fuels (pfuel) which have a higher prevalence of tuberculosis (Sumpter & Chandramohan, 2013), asthma (Lin et al., 2013), other cardiovascular diseases (Mitter et al., 2016), and low birth weight (Pope et al., 2010). People with multimorbidity conditions generally have higher out-of-pocket expenditures (oop), which adds to household financial burdens (Sum et al., 2018), and live/ survive without health care due to the overwhelming cost (Callander et al., 2017). ...
Member countries of the United Nations have pledged to ensure access to affordable, reliable, and sustainable energy for all by 2030 (Sustainable Development Goal 7). However, energy poverty continues to be a significant challenge for billions of people. Empirical research established a connection between energy poverty and traditional public health indicators such as overall mortality rate, but relatively little is known about its holistic impact on public health and in particular on health vulnerability. This research establishes a holistic measure of public health using panel data from 143 countries between 2000 and 2016 to analyze the impact of energy poverty on health vulnerability. Using Ordinary Least‐Squares (OLS), fixed effects, system Generalized Method of Moments (GMM), and quantile regression approaches, our results show that reducing energy poverty mitigates health vulnerability. Energy poverty amplifies the susceptibility to negative health outcomes (sensitivity) and diminishes a population's capacity to respond to public health crises (resilience). The analysis also reveals a heterogeneous impact of energy poverty on health vulnerability associated with the socio‐economic development level of the region, with the largest increase being in more developed and high‐income regions.
... The issue of exposure to low levels of CO should be of serious concern in non-electrified homes wherein the combination of regular usage of cooking and heating devices that use carbon fuels with inadequate indoor ventilation practices could contribute to higher indoor CO exposure than outdoor conditions [15][16][17][18][19][20][21]. Vanker et al. found an association between fossil fuel use and degraded indoor air quality in homes, specifically higher levels of CO and benzene [22]. ...
Carbon monoxide (CO) is a colorless, odorless gas emitted from carbon fuel combustion. In this study we monitored indoor carbon monoxide (CO) levels for 120 homes over three seasons in the North Denver metropolitan region as part of an environmental justice initiative to quantify health and social well-being impacts from a major freeway construction upgrade nearby. Urban outdoor CO levels are typically very low (less than 1 ppm in Denver) due to air pollution control strategies and technologies implemented over the past several decades. However, people can still be exposed to higher than outdoor levels of CO in their homes due to the operation of indoor appliances that use carbon fuels such as natural gas. Our data show that ~10% of the homes had consistent daily average levels of CO above 3.5 ppm and 24-57% of the homes showed peaks greater than 9 ppm. While much higher levels can result in CO poisoning and fatalities, these lower levels of CO have been associated with adverse health impacts, especially pregnant women, and sensitive populations. Our results highlight the need for increasing awareness regarding CO exposures in homes with gas appliances and motivate the transition from non-electrified homes toward electrification.
... There is heterogeneous research present regarding the association between indoor gas stove use and childhood asthma. A 2013 meta-analysis of 41 studies on the association between indoor nitrogen oxide and gas cooking on asthma in children concluded that gas cooking increases the risk of asthma (3). This meta-analysis had limitations; notably, all studies included were observational, and there was heterogeneity that existed in the form of participant demographics, study region, proportion of gas cooking, and year of publication between studies (3). ...
Objective
To examine whether the use of gas stoves in the home is associated with increased asthma severity among children and adolescents ages 0-17 in the US.
Methods
Using the 2020 CDC Asthma Call-Back Survey for children, the association between gas stove usage and childhood asthma symptoms, asthma attack or episode, and emergency department visit for asthma was assessed. With a cross-sectional study design, bivariate analyses and multivariable logistic regression were conducted. Survey weights were used in the analyses for US population-based estimates.
Results
Children who live in a household that uses gas for cooking or has a gas stove had 1.133 (95% CI: 0.48, 2.68)) times the odds of having an asthma attack or episode within the past 12 months, 9.141 (95% CI: 1.99, 42.06) times the odds of having visited the emergency department or urgent care within the past 12 months, and 1.739 (95% CI: 1.02, 2.95) times the odds of recent symptoms of asthma compared to children who live in a household that does not use gas for cooking or does not have a gas stove, controlling for all confounders. There is an association between the usage of gas stoves and asthma symptoms, asthma attacks/episodes, and ED visits among asthmatic children. Reducing the exposure of gas stove usage should be a consideration in regards to existing and future interventions to prevent childhood asthma and reduce exacerbation of underlying childhood asthma.
... %) of current childhood asthma in the U. S. is attributable to residential gas stoves, varying in magnitude by state [8]. These estimates accounted for the proportion of children with gas stoves in their residences as well as a prior meta-analysis of the associations between current asthma and household use of gas for cooking [155], which some suggest does not meet the threshold for causality [156]. However, it is not well understood which pollutant exposures these health impacts are attributed to. ...
Building electrification is the movement to shift building operational energy use from fossil fuels toward electricity. It has been pursued mainly to reduce greenhouse gas (GHG) emissions from the building sector. We present here ten questions concerning building electrification and attempt to answer them in the context of the existing literature. Our questions span dimensions of policy, life cycle impacts on energy and environment, technological advances and challenges, indoor and outdoor air quality, health, economics, and social-behavioral factors. We find that while much of the extant research predicts that building electrification will provide benefits in terms of GHG emissions, pollutant exposures, and economic impacts, it remains limited to a narrow set of geographic regions and typically fails to capture the full extent of life cycle environmental impacts. Additionally, despite logical inferences for likely health benefits, we were unable to identify explicit studies of the health impacts of building electrification. We also find a common theme that, for building electrification to be successful in reducing GHG emissions, costs, and adverse grid impacts, it should be approached in parallel with increased building energy efficiency, grid renewable power, and smart grid infrastructure. Finally, we find that people hold strong opinions about fuel options in their homes, and the relationship between preferences and energy use is complicated. To shift people's beliefs around electrification, government-originating communications can highlight the benefits, but one must still account for heterogeneous household conditions. We conclude by suggesting key research areas needed to approach building electrification effectively and equitably.
... Exposure to household air pollution nearly doubles the risk of childhood lower respiratory tract infections and is responsible for increased risk of non-communicable diseases, including stroke, ischemic heart disease, chronic obstructive pulmonary disease, and lung cancer [33][34][35][36]. A meta-analysis of 41 studies has shown that children living in a home with a gas stove have a 32% increased risk of developing asthma attacks [37]. Finally, indoor air pollution can contribute to aggravating airborne infections. ...
Background
Pollution of the indoor environment represents a concern for human health, mainly in case of prolonged exposure such as in the case of women, children, the elderly, and the chronically ill, who spend most of their time in closed environments.
Main body
The aim of the study is to organize a group of experts in order to evaluate the evidence and discuss the main risk factors concerning indoor air and the impact on human health as well as challenging factors regarding preventive strategies to reduce pollution. The experts highlighted the main risk factors concerning indoor air, including poor ventilation, climatic conditions, chemical substances, and socio-economic status. They discussed the impact on human health in terms of mortality and morbidity, as well as challenging factors regarding preventive strategies to reduce pollution.
Conclusion
The experts identified strategies that can be reinforced to reduce indoor pollution and prevent negative consequences on human health at national and local levels.
... Second, indoor air pollution, from sources such as smoking and cooking, can also irritate the airways and lead to respiratory diseases. [57][58][59] However, due to the individuallevel nature and the scale of the study, we were not able to consider indoor air pollution in our analysis. Third, it is not certain whether the patients were at or around their home addresses during the five-day cumulative exposure window. ...
Background
There is an increasing body of evidence associating short-term ambient nitrogen dioxide (NO2) exposure with asthma-related hospital admissions in children. However, most studies have relied on temporally resolved exposure information, potentially ignoring the spatial variability of NO2. We aimed to investigate how daily NO2 estimates from a highly resolved spatio-temporal model are associated with the risk of emergency hospital admission for asthma in children in England.
Methods
We conducted a time-stratified case-crossover study including 111,766 emergency hospital admissions for asthma in children (aged 0–14 years) between 1st January 2011 and 31st December 2015 in England. Daily NO2 levels were predicted at the patients’ place of residence using spatio-temporal models by combining land use data and chemical transport model estimates. Conditional logistic regression models were used to obtain the odds ratios (OR) and confidence intervals (CI) after adjusting for temperature, relative humidity, bank holidays, and influenza rates. The effect modifications by age, sex, season, area-level income deprivation, and region were explored in stratified analyses.
Results
For each 10 µg/m³ increase in NO2 exposure, we observed an 8% increase in asthma-related emergency admissions using a five-day moving NO2 average (mean lag 0–4) (OR 1.08, 95% CI 1.06–1.10). In the stratified analysis, we found larger effect sizes for male (OR 1.10, 95% CI 1.07–1.12) and during the cold season (OR 1.10, 95% CI 1.08–1.12). The effect estimates varied slightly by age group, area-level income deprivation, and region.
Significance
Short-term exposure to NO2 was significantly associated with an increased risk of asthma emergency admissions among children in England. Future guidance and policies need to consider reflecting certain proven modifications, such as using season-specific countermeasures for air pollution control, to protect the at-risk population.
... Extensive epidemiological and clinical experimental investigations consistently demonstrate a compelling association between air pollution exposure and the increased risk of exacerbating asthma symptoms. These studies have consistently shown a clear link between poor air quality and increased asthma incidence in both children and adults [29][30][31]. Furthermore, long-term exposure to various types of ambient air pollution, such as Traffic-related air pollution (TRAP) and indoor pollutants, has been identified as a significant factor in asthma development [32,33]. ...
Background: Asthma is a widespread chronic respiratory disease that poses a significant public health challenge. The current study investigated the associations between air pollution and asthma severity among individuals residing near the Sohar industrial port (SIP) in Oman. Despite the presence of multiple major industrial complexes in Oman, limited knowledge regarding their impact on respiratory health is accredited. Hence, the primary objective of this study is to offer valuable insights into the respiratory health consequences of industrial air pollution in Al Batinah North. Methods: The state health clinics' records for patient visits related to asthma were collected for the timeframe spanning 2014 to 2022. Exposure was defined as the distance from SIP, Majan Industerial Area (MIA) and Sohar Industerial Zone (SIZ) to determine high, intermediate, and low exposure zones (12 km, respectively). Exposure effect modifications by age, gender, and smoking status were also examined. Results: The conducted cross-sectional study of 410 patients (46.1% males and 53.9% females) living in over 17 areas around SIP revealed that 73.2% of asthmatics were under 50 years old, with severity significantly associated with closeness to the port. Risk ratios were estimated to be (RR:2.42; CI95%: 1.01–5.78), (RR:1.91; CI95%: 1.01–3.6), and (RR:1.68; CI95%: 0.92–3.09) for SIP, MIP and SIZ areas, respectively, compared to the control area. Falaj Al Qabail (6.4 km) and Majees (6 km) had the highest number of asthma patients (N. 69 and N. 72), and highest percentages of severe asthma cases among these patients (28% and 24%) with significant risk ratios (RR:2.97; CI95%: 1.19–7.45 and RR:2.55; CI95%: 1.00–6.48), correspondingly. Moreover, severe asthma prevalence peaked in the 25-50 age group (RR:2.05; CI95%: 1.26–3.33), and this linkage between asthma and age was much more pronounced in males than females. Smoking and exposure to certain contaminant (dust and smoke) increased also the risk of severe asthma symptoms, but their effects were less important in the high risk zone, suggesting much more important risk factor. A neural network model accurately predicted asthma risk (94.8% accuracy), with proximity to Sohar Industrial Port as the most influential predictor. Conclusion: The study highlights the High asthma burden near Sohar Industrial Port, linked to port proximity and smoking and wind direction as major risk factors. These findings inform vital public health policies to reduce air pollution and improve respiratory health in the region, prompting national policy review.
... These investigators estimated that annual methane emission from gas stoves in U.S. homes have a climate change-forcing impact equivalent to the annual methane emissions of 500,000 cars. In the indoor environment, natural gas is also used for cooking and is well known to affect indoor air quality (26). The available evidence about emissions from natural gas appliances (e.g., furnaces, water heaters) used in residential and commercial conditions comes from experiments under carefully controlled conditions, likely leading to underestimates of true pollutant emissions from natural gas appliances in real-world residential and commercial settings (27). ...
Indoor sources of air pollution worsen indoor and outdoor air quality. Thus, identifying and reducing indoor pollutant sources would decrease both indoor and outdoor air pollution, benefit public health, and help address the climate crisis. As outdoor sources come under regulatory control, unregulated indoor sources become a rising percentage of the problem. This American Thoracic Society workshop was convened in 2022 to evaluate this increasing proportion of indoor contributions to outdoor air quality. The workshop was conducted by physicians and scientists, including atmospheric and aerosol scientists, environmental engineers, toxicologists, epidemiologists, regulatory policy experts, and pediatric and adult pulmonologists. Presentations and discussion sessions were centered on 1) the generation and migration of pollutants from indoors to outdoors, 2) the sources and circumstances representing the greatest threat, and 3) effective remedies to reduce the health burden of indoor sources of air pollution. The scope of the workshop was residential and commercial sources of indoor air pollution in the United States. Topics included wood burning, natural gas, cooking, evaporative volatile organic compounds, source apportionment, and regulatory policy. The workshop concluded that indoor sources of air pollution are significant contributors to outdoor air quality and that source control and filtration are the most effective measures to reduce indoor contributions to outdoor air. Interventions should prioritize environmental justice: Households of lower socioeconomic status have higher concentrations of indoor air pollutants from both indoor and outdoor sources. We identify research priorities, potential health benefits, and mitigation actions to consider (e.g., switching from natural gas to electric stoves and transitioning to scent-free consumer products). The workshop committee emphasizes the benefits of combustion-free homes and businesses and recommends economic, legislative, and education strategies aimed at achieving this goal.
... Children are susceptible to the effects of second-hand smoke because they breathe faster and so, take in more smoke. Some studies also provide evidence for correlation between indoor air pollution due to cooking with solid fuels with respiratory disorders 4 . ...
Background: This study aimed to see association of exposure to solid fuel for cooking and second-hand smoking(SHS) with asthma and recurrent wheezing in children. Carboxyhaemoglobin (COHb) levels were also estimatedlevels in these children and their relation to exposure to solid fuels and SHS was assessed.Methods: The study enrolled 124 children in two groups; 72(58.1%) in Group 1 with asthma/recurrent wheezingand 52(41.9%) in Group 2 as controls. Exposure to SHS and solid fuel were assessed using a simple questionnairein both the groups. COHb levels were estimated non-invasively and it’s relation to demographic variables,occurrence of asthma, exposure to SHS and solid fuel was estimated.Conclusion: The study reported significant association of SHS and use of solid fuel among children with asthmaand recurrent wheezing seen in 26(36.2%) and 26(36.2%) respectively. The study showed that COHb levels weregreatly elevated among children with asthma and wheezing conditions (5.45%) as compared to controls (2.95%).The study showed association of COHb levels with use of SHS and solid fuel exposure which were found tobe (5.31%, 5.98%) respectively, thus emphasizing the need for interventions to reduce these potential sources ofcarbon monoxide exposure.
... Several cross-sectional epidemiological studies have reported adverse respiratory health effects in children associated with indoor gas appliances and/or high NO 2 levels (Hölscher et al., 2000;Lin et al., 2013;Moshammer et al., 2010;Paulin et al., 2017). However, the epidemiological evidence on adults is more limited. ...
... 26 NO 2 is a well-established risk factor for asthma in children. 27,28 In studies of adults using central site and model-based estimates of ambient NO 2 exposure, decreased pulmonary function, [29][30][31][32] greater risk of COPD exacerbations, 16 and increased hospitalizations and mortality have been reported. 2,3,[6][7][8]33 Despite this research, the health effects of NO 2 on humans and the mechanisms underlying these health effects are still not well understood. ...
Introduction
Indoor nitrogen dioxide (NO 2 ) sources include gas heating, cooking, and infiltration from outdoors. Associations with pulmonary function, systemic inflammation, and oxidative stress in patients with chronic obstructive pulmonary disease (COPD) are uncertain.
Methods
We recruited 144 COPD patients at the VA Boston Healthcare System between 2012 and 2017. In-home NO 2 was measured using an Ogawa passive sampling badge for a week seasonally followed by measuring plasma biomarkers of systemic inflammation (C-reactive protein [CRP] and interleukin-6 [IL-6]), urinary oxidative stress biomarkers (8-hydroxy-2'deoxyguanosine [8-OHdG] and malondialdehyde [MDA]), and pre- and postbronchodilator spirometry. Linear mixed effects regression with a random intercept for each subject was used to assess associations with weekly NO 2 . Effect modification by COPD severity and by body mass index (BMI) was examined using multiplicative interaction terms and stratum-specific effect estimates.
Results
Median (25%ile, 75%ile) concentration of indoor NO2 was 6.8 (4.4, 11.2) ppb. There were no associations observed between NO 2 with CRP, 8-OHdG, or MDA. Although the confidence intervals were wide, there was a reduction in prebronchodilator FEV 1 and FVC among participants with more severe COPD (FEV 1 : –17.36 mL; –58.35, 23.60 and FVC: –28.22 mL; –91.49, 35.07) that was greater than in patients with less severe COPD (FEV 1 : –1.64 mL; –24.80, 21.57 and FVC: –6.22 mL; –42.16, 29.71). In participants with a BMI <30, there was a reduction in FEV 1 and FVC.
Conclusions
Low-level indoor NO 2 was not associated with systemic inflammation or oxidative stress. There was a suggestive association with reduced lung function among patients with more severe COPD and among patients with a lower BMI.
... This can lead to better-targeted interventions: Much of the air quality interventions in London have focussed on improving ambient concentrations. Whilst ensuring clean outdoor air is essential for improving population exposure, the work here indicates that ensuring proper kitchen ventilation and accelerating the provision of clean households fuels in UK homes may lead to greater reductions in childhood exposure to PM 2.5 , which is supported by wider research (Gruenwald et al., 2022;Knibbs et al., 2018a,Knibbs et al., 2018bLin et al., 2013). ...
... Cooking gas, although cited as the "cleaner fuel", has been established to be a source of significant indoor air pollutants including PM 2.5 , nitrogen dioxide, carbon monoxide, benzene and formaldehyde [1]. Cooking with gas increases the risk of childhood asthma [4]. In this context, focussing on improving ventilation in the kitchens may have a larger impact on improving asthma outcomes. ...
House dust mite (HDM) allergens are one of the most important causes of allergenic diseases in the indoor environment. The World Health Organization (WHO) has defined risk thresholds for Group I HDM allergens as a concentration of 2 and 10 μg/mL in dust for producing asthma risk and polar asthma attacks, respectively. Continuing exposure to high concentrations of HDM allergens greatly increases the risk of developing allergic diseases. Therefore, it’s necessary to determine the exposure levels of HDM allergens to estimate the risk. So, various approaches have been developed to directly or indirectly detect HDM allergens in the environment. This paper overviews the developmental progress of HDM allergen detection and introduces the principle of HDM allergen detection methods, including semi-quantitative radioallergosorbent test (RAST), ACAREX test, dot immunobinding assay (DIBA), radioimmunoassay (RIA) which combines the high sensitivity and accuracy, enzyme-linked immunosorbent assay (ELISA) with high accuracy, fluorescent multiple arrays which can simultaneously detect multiple HDM allergens, polymerase chain reaction (PCR), and liquid chromatograph-mass spectrometer (LC-MS) with high sensitivity and accuracy. The paper provides an overall understanding of the development of HDM allergen detection methods and guidance for choosing an appropriate method to detect HDM allergens.
This chapter of the New York City Panel on Climate Change 4 (NPCC4) report considers climate health risks, vulnerabilities, and resilience strategies in New York City's unique urban context. It updates evidence since the last health assessment in 2015 as part of NPCC2 and addresses climate health risks and vulnerabilities that have emerged as especially salient to NYC since 2015. Climate health risks from heat and flooding are emphasized. In addition, other climate‐sensitive exposures harmful to human health are considered, including outdoor and indoor air pollution, including aeroallergens; insect vectors of human illness; waterborne infectious and chemical contaminants; and compounding of climate health risks with other public health emergencies, such as the COVID‐19 pandemic. Evidence‐informed strategies for reducing future climate risks to health are considered.
Background: Asthma is a widespread chronic respiratory disease that poses a significant public health challenge. The current study investigated the associations between air pollution and asthma severity among individuals residing near the Sohar industrial port (SIP) in Oman. Despite the presence of multiple major industrial complexes in Oman, limited knowledge regarding their impact on respiratory health is accredited. Hence, the primary objective of this study is to offer valuable insights into the respiratory health consequences of industrial air pollution in Al Batinah North. Methods: The state health clinics’ records for patient visits related to asthma were collected for the timeframe spanning 2014 to 2022. Exposure was defined as the distance from the SIP, Majan Industerial Area (MIA), and Sohar Industerial Zone (SIZ) to determine high-, intermediate-, and low-exposure zones (<6 km, 6–12 km and >12 km, respectively). Exposure effect modifications by age, gender, and smoking status were also examined. Results: The conducted cross-sectional study of 410 patients (46.1% males and 53.9% females) living in over 17 areas around SIP revealed that 73.2% of asthmatics were under 50 years old, with severity significantly associated with closeness to the port. Risk ratios were estimated to be (RR:2.42; CI95%: 1.01–5.78), (RR:1.91; CI95%: 1.01–3.6), and (RR:1.68; CI95%: 0.92–3.09) for SIP, MIP, and SIZ areas, respectively, compared to the control area. Falaj Al Qabail (6.4 km) and Majees (6 km) had the highest number of asthma patients (N 69 and N 72) and highest percentages of severe asthma cases among these patients (28% and 24%) with significant risk ratios (RR:2.97; CI95%: 1.19–7.45 and RR:2.55; CI95%: 1.00–6.48), correspondingly. Moreover, severe asthma prevalence peaked in the 25–50 age group (RR:2.05; CI95%: 1.26–3.33), and this linkage between asthma and age was much more pronounced in males than females. Smoking and exposure to certain contaminants (dust and smoke) also increased the risk of severe asthma symptoms, but their effects were less important in the high-risk zone, suggesting much more important risk factors. A neural network model accurately predicted asthma risk (94.8% accuracy), with proximity to SIP as the most influential predictor. Conclusions: This study highlights the high asthma burden near SIP, linked to port proximity, smoking, and wind direction as major risk factors. These findings inform vital public health policies to reduce air pollution and improve respiratory health in the region, prompting national policy review.
Gas range use has direct health effects-beyond those from climate change related to fossil fuels. If kitchens are not well ventilated, benzene, nitrogen dioxide, and other VOCs may reach levels known to harm health.
The recent Inflation Reduction Act (IRA) proposals are expected to take a number of measures. These include financial incentives to improve energy efficiency, reduce pollution and increase the climate resilience of households. Furthermore, the use of natural resources (NTR) is critical in driving energy demand in industry and households. However, NTRs also play an important role in increasing carbon emissions (CO2), which can lead to various diseases. Healthcare (HLT) has complex issues such as rising costs due to inflation (INF), stalled improvements in population-wide outcomes, stalled access due to clinical staff shortages, and COVID-19 intensify. Therefore, this study aimed to investigate the effects of NTR, CO2, and INF on HLT. In addition, this study also considers short-term and long-term volatility and does so by employing an asymmetric (non-linear) ARDL model. Application of NARDL resulted in positive shocks to NTR, INF, and CO2 that increased HLT, whereas negative shocks to NTR, INF, and CO2 decreased HLT. Based on the findings, it is recommended that there is an urgent need to identify measures that can be taken to utilize the NTR best and facilitate the sustainable efforts being promoted by the IRA.
Asthma, which affects some 300 million people worldwide and caused 455,000 deaths in 2019, is a significant burden to suffers and to society. It is the most common chronic disease in children and represents one of the major causes for years lived with disability. Significant efforts are made by organizations such as WHO in improving the diagnosis, treatment and monitoring of asthma. However asthma prevention has been less studied. Currently there is a concept of pre- diabetes which allows a reduction in full blown diabetes if diet and exercise are undertaken. Similar predictive states are found in Alzheimer's and Parkinson's diseases. In this paper we explore the possibilities for asthma prevention, both at population level and also investigate the possibility of defining a state of pre-asthma, in which intensive treatment could reduce progression to asthma. Since asthma is a heterogeneous condition, this paper is concerned with allergic asthma. A subsequent one will deal with late onset eosinophilic asthma.
Dear Editor, Household Air Pollution [HAP] has proven to be associated with an increased risk of acquiring asthma, lung cancer, pulmonary tuberculosis, and acute respiratory infections in adults and children, along with Chronic Obstructive Pulmonary Disease [COPD], cerebrovascular disease, ischemic heart disease, low birth weight, and stillbirth [1]. This pollution is caused primarily by the absence of clean fuels, which includes electricity, biogas, natural gas, liquefied petroleum gas (LPG), solar, or alcohol fuels. Owing to the absence of clean fuels, individuals resort to the use of biomass to meet their needs, exposing themselves to the detrimental effects of biomass usage. Unfortunately, Pakistan is one of the worst-faring victims of this predicament. As of 2020, only 49.3% of Pakistanis primarily relied on clean fuels and technologies for cooking [2]. With only 26% of rural areas having access to clean fuels, traditional, inefficient three-stone stoves for biomass combustion are typical in rural areas[2][3]. Such stoves expel poisonous gasses, including Nitrogen oxides, Carbon monoxide, and formaldehyde, in addition to several toxic organic compounds depending on the type of biomass used, all detrimental to human health [4]. In urban areas, especially in winter, widespread gas shortages are prevalent, restricting an unknown number of citizens to biomass combustion for their day-to-day purposes. In both scenarios, the harms of HAP are imminent. Unfortunately, using gas stoves in poorly ventilated areas also shows milder effects of HAP [5]. Alarmingly, despite the adverse impact and the high prevalence of HAP, the matter remains neglected, with only very few studies connecting the above-stated health risks with the Pakistani population, evaluating the burden Pakistan bears because of HAP, and assessing the correct strategies for intervention. Such studies would result in implementing specific research-backed mitigation strategies customized to be specifically applicable to different socioeconomic backgrounds and regions of Pakistan, for example, efficient ventilatory systems relevant to Pakistani houses designed to reduce HAP. In the meantime, examples of general policies include, but are not limited to, television advertisements, awareness drives, and allotting larger budgets towards cleaner fuel provision. For people utilizing primitive three-stone stoves, a plancha stove, comprising simply a stove and a chimney, can also be provided. The usage of such stoves is associated with a significantly reduced exposure to HAP [6]. Individually, when operating stoves for any purpose, it is crucial to prioritize ventilation. ---Continue
Several recent news stories have alarmed many politicians and members of the public by reporting that indoor air pollution from gas stoves causes about 13% of childhood asthma in the United States. Research on the reproducibility and trustworthiness of epidemiological risk assessments has identified a number of common questionable research practices (QRPs) that should be avoided to draw sound causal conclusions from epidemiological data. Examples of such QRPs include claiming causation without using study designs or data analyses that allow valid causal inferences; generalizing or transporting risk estimates based on data for specific populations, time periods, and locations to different ones without accounting for differences in the study and target populations; claiming causation without discussing or quantitatively correcting for confounding, external validity bias, or other biases; and not mentioning or resolving contradictory evidence. We examine the recently estimated gas stove-childhood asthma associations from the perspective of these QRPs and conclude that it exemplifies all of them. The quantitative claim that about 13% of childhood asthma in the United States could be prevented by reducing exposure to gas stove pollution is not supported by the data collected or by the measures of association (Population Attributable Fractions) used to analyze the data. The qualitative finding that reducing exposure to gas stove pollution would reduce the burden of childhood asthma in the United States has no demonstrated validity. Systematically checking how and whether QRPs have been addressed before reporting or responding to claims that everyday exposures cause substantial harm to health might reduce social amplification of perceived risks based on QRPs and help to improve the credibility and trustworthiness of published epidemiological risk assessments.
Objective: Funnel plots (plots of effect estimates against sample size) may be useful to detect bias in meta-analyses that were later contradicted by large trials. We examined whether a simple test of asymmetry of funnel plots predicts discordance of results when meta-analyses are compared to large trials, and we assessed the prevalence of bias in published meta-analyses. Design: Medline search to identify pairs consisting of a meta-analysis and a single large trial (concordance of results was assumed if effects were in the same direction and the meta-analytic estimate was within 30
The impact of single exposures on asthma development is better understood than the effect of multiple exposures. The objective of the present study was to evaluate the effect of combined early exposure to dog allergen (Can-f1) plus indoor nitrogen dioxide (NO 2 ) or environmental tobacco smoke (ETS) on asthma and bronchial hyperreactivity (BHR) in a high-risk birth cohort. We also aimed to assess atopy's impact on the effects of these exposures.
Peri-birth ETS exposure was measured using cord blood cotinine (CCot). During year 1, atopy, NO 2 , Can-f1, and urinary cotinine (UCot) were measured. At 7 yrs of age, 380 children were assessed for asthma and BHR. Exposure effects were determined using stepwise multiple linear regression.
Co-exposure to elevated Can-f1 and NO 2 , or Can-f1 and ETS (CCot), increased risk for asthma, relative to having neither such exposure (OR 4.8 (95% CI 1.1–21.5) and 2.7 (1.1–7.1), respectively); similar risks resulted when substituting dog ownership for allergen. Atopy increased asthma and BHR risk associated with several exposures; notably, atopy with elevated UCot, relative to atopy without such exposure, increased risk of BHR (OR 3.1 (95% CI 1.1–8.6)).
In a high-risk birth cohort, early co-exposure to Can-f1 and NO 2 or ETS increased the risk of incident asthma. Atopy increased the risk of asthma and BHR associated with ETS.
To assess whether non-polluting, more effective home heating (heat pump, wood pellet burner, flued gas) has a positive effect on the health of children with asthma.
Randomised controlled trial.
Households in five communities in New Zealand.
409 children aged 6-12 years with doctor diagnosed asthma.
Installation of a non-polluting, more effective home heater before winter. The control group received a replacement heater at the end of the trial.
The primary outcome was change in lung function (peak expiratory flow rate and forced expiratory volume in one second, FEV(1)). Secondary outcomes were child reported respiratory tract symptoms and daily use of preventer and reliever drugs. At the end of winter 2005 (baseline) and winter 2006 (follow-up) parents reported their child's general health, use of health services, overall respiratory health, and housing conditions. Nitrogen dioxide levels were measured monthly for four months and temperatures in the living room and child's bedroom were recorded hourly.
Improvements in lung function were not significant (difference in mean FEV(1) 130.7 ml, 95% confidence interval -20.3 to 281.7). Compared with children in the control group, however, children in the intervention group had 1.80 fewer days off school (95% confidence interval 0.11 to 3.13), 0.40 fewer visits to a doctor for asthma (0.11 to 0.62), and 0.25 fewer visits to a pharmacist for asthma (0.09 to 0.32). Children in the intervention group also had fewer reports of poor health (adjusted odds ratio 0.48, 95% confidence interval 0.31 to 0.74), less sleep disturbed by wheezing (0.55, 0.35 to 0.85), less dry cough at night (0.52, 0.32 to 0.83), and reduced scores for lower respiratory tract symptoms (0.77, 0.73 to 0.81) than children in the control group. The intervention was associated with a mean temperature rise in the living room of 1.10 degrees C (95% confidence interval 0.54 degrees C to 1.64 degrees C) and in the child's bedroom of 0.57 degrees C (0.05 degrees C to 1.08 degrees C). Lower levels of nitrogen dioxide were measured in the living rooms of the intervention households than in those of the control households (geometric mean 8.5 microg/m(3) v 15.7 microg/m(3), P<0.001). A similar effect was found in the children's bedrooms (7.3 microg/m(3) v 10.9 microg/m(3), P<0.001).
Installing non-polluting, more effective heating in the homes of children with asthma did not significantly improve lung function but did significantly reduce symptoms of asthma, days off school, healthcare utilisation, and visits to a pharmacist.
Clinical Trials NCT00489762.
Elevated concentrations of nitrogen dioxide (NO2) are produced in the home by the use of unvented gas appliances. In studies on potential health effects of indoor exposure to NO2, exposure has mostly been estimated from the presence or absence of sources like gas cookers in the home. This leads to misclassification of exposure, as NO2 concentrations in the home depend also on source use, ventilation habits, time budgets, etc. The availability of cheap, passive monitoring devices has made it possible to measure indoor concentrations of NO2 directly in health effects studies, albeit with averaging times of one to several days. So far, it has not been evaluated whether this increases the sensitivity of a study to detect health effects of NO2. In this paper, a comparison is made between NO2 sources and weekly average indoor NO2 measurements, as predictors of pulmonary function in a study among children aged 6-12 years. The relationship between exposure and lung functions was found to be generally non-significant in this study. The results further suggested that in this study, measuring indoor NO2 concentrations with passive monitors offered no advantage over the simple use of source presence as exposure variable.
The effect of indoor exposure to nitrogen dioxide on respiratory health was studied over a period of 2 yr in a population of nonsmoking Dutch children 6 to 12 yr of age. Lung function was measured at the schools, and information on respiratory symptoms was collected from a self-administered questionnaire completed by the parents of the children. Nitrogen dioxide was measured in the homes of all children with Palmes' diffusion tubes. In addition, information on smoking and dampness in the home was collected by questionnaire. There was no relationship between exposure to nitrogen dioxide in the home and respiratory symptoms. Respiratory symptoms were found to be associated with exposure to tobacco smoke and home dampness. There was a weak, negative association between maximal midexpiratory flow (MMEF) and exposure to nitrogen dioxide. FEV1, peak expiratory flow, and MMEF were all negatively associated with exposure to tobacco smoke. Home dampness was not associated with pulmonary function. Lung function growth, measured over a period of 2 yr, was not consistently associated with any of the indoor exposure variables. The development of respiratory symptoms over time was not associated with indoor exposure to nitrogen dioxide. There was a significant association between exposure to environmental tobacco smoke in the home and the development of wheeze. There was also a significant association between home dampness and the development of cough.
In a survey of 1,355 children six- to 12 years of age, the risk of hospitalization for respiratory illness among children before age two years was increased when gas was used for cooking at home (p less than 0.001) or at least one of the parents smoked (p less than 0.02). The occurrence of cough with colds in children also was significantly increased when one or both parents smoked (p less than 0.001). Small but significant increases (p less than .05) in the mean values of forced expiratory volume at one second, the flow rate at 75 percent of the forced vital capacity, and the forced expiratory flow rate from 25 percent to 75 percent of the vital capacity (FEF25-75) were seen after administering inhaled isoproterenol to children whose parents smoked (n = 94) but not among children whose parents did not smoke (n = 89); this was not seen in association with gas cooking. Thus, exposure of children during the first two years of life to gas cooking or cigarette smoking appears to be associated with an increased risk of hospitalization for respiratory illness, and cigarette smoking appears to be associated with a more consistent response to inhaled bronchodilator among six- to 12-year-old children with no other history of chronic respiratory illness.
The indoor environment of 80 houses in the Latrobe Valley, Victoria, Australia was assessed during six visits performed bi-monthly over a period of one year. Children between 7 and 14 years of age residing in the houses were included, resulting in 148 study children, 53 of whom were asthmatic. A respiratory health questionnaire was completed and skin prick tests performed. Significant risk factors for asthma were: exposure to a gas stove (OR=3.15, 95% CI 1.28-7.72), and indoor pets (OR= 2.68, 95% CI 1.07-6.70). Exposure to airborne Aspergillus spores (+10 CFU/m3, OR=1.51, 95% CI 1.05-2.18) was a risk factor for atopy, while exposure to a gas stove (OR=2.32, 95% CI 1.04-5.18) was a risk factor for respiratory symptoms. In conclusion, exposure to gas stoves, fungal spores and pets in the home were identified as statistically significant risk factors for respiratory health in children.
Background
The effects of indoor exposure to volatile organic compounds (VOCs), including formaldehyde, on respiratory health are not clearly understood. The aim of this study was to determine the independent effects of VOCs and other common environmental exposures in the home on the risk and severity of persistent wheezing illness in children.
Methods
Total volatile organic compounds, formaldehyde, nitrogen dioxide, damp (on a four category scale of % wood moisture equivalent), and environmental tobacco smoke (from salivary cotinine) were measured objectively in the homes of 193 children with persistent wheezing illness and 223 controls aged 9–11 years in Nottingham, UK.
Results
The risk of wheezing illness was significantly increased only in relation to damp (odds ratio (OR) per increasing category=1.32 (95% confidence interval (CI), 1.00 to 1.75)), and was unrelated to the other exposures measured. Among cases, formaldehyde and damp were associated with more frequent nocturnal symptoms (OR per increasing quartile and category, respectively, 1.45 (1.06 to 1.98) and 1.97 (1.10 to 3.53)), significantly more so in atopic cases, but there was no effect of total volatile organic compounds, nitrogen dioxide, or cotinine.
Conclusions
Domestic volatile organic compounds are not a major determinant of risk or severity of childhood wheezing illness, though formaldehyde may increase symptom severity. Indoor damp increases both the risk and severity of childhood wheezing illness.
This article reviews (i) the role of nitrogen dioxide (NO2) in respiratory diseases, including asthma, and (ii) appraises whether current guidelines for NO2 confer an adequate margin of safety for asthmatics. Medline and Excerpta Medica (1966-1997) were searched to retrieve original epidemiological studies which examined the relationship between NO2 and respiratory diseases including asthma. Previously reported reviews of controlled clinical studies were also utilised. The results of this search were then related to current NO2 guidelines. The review of 23 outdoor and 36 indoor studies suggests that respiratory effects are associated with levels of NO2 that may be encountered in common domestic and outdoor settings. Meta-analyses of studies among the general population of children demonstrate a 20% increase in respiratory problems, including increases of asthma by 20%, and wheezing by 12% in households with gas cookers. Epidemiological evidence also indicates that hourly NO2 values of 80 ppb are likely to cause respiratory symptoms in the general population of children. Such levels are frequently present in domestic and school settings. Critical appraisal of the epidemiological evidence indicates the need for a revision of NO2 guidelines to protect both asthmatics and the general population, especially children.
Indoor air pollution from a range of household cooking fuels has been implicated in the development and exacerbation of respiratory diseases. In both rich and poor countries, the effects of cooking fuels on asthma and allergies in childhood are unclear. We investigated the association between asthma and the use of a range of cooking fuels around the world.
For phase three of the International Study of Asthma and Allergies in Childhood (ISAAC), written questionnaires were self-completed at school by secondary school students aged 13-14 years, 244 734 (78%) of whom were then shown a video questionnaire on wheezing symptoms. Parents of children aged 6-7 years completed the written questionnaire at home. We investigated the association between types of cooking fuels and symptoms of asthma using logistic regression. Adjustments were made for sex, region of the world, language, gross national income, maternal education, parental smoking, and six other subject-specific covariates. The ISAAC study is now closed, but researchers can continue to use the instruments for further research.
Data were collected between 1999 and 2004. 512 707 primary and secondary school children from 108 centres in 47 countries were included in the analysis. The use of an open fire for cooking was associated with an increased risk of symptoms of asthma and reported asthma in both children aged 6-7 years (odds ratio [OR] for wheeze in the past year, 1·78, 95% CI 1·51-2·10) and those aged 13-14 years (OR 1·20, 95% CI 1·06-1·37). In the final multivariate analyses, ORs for wheeze in the past year and the use of solely an open fire for cooking were 2·17 (95% CI 1·64-2·87) for children aged 6-7 years and 1·35 (1·11-1·64) for children aged 13-14 years. Odds ratios for wheeze in the past year and the use of open fire in combination with other fuels for cooking were 1·51 (1·25-1·81 for children aged 6-7 years and 1·35 (1·15-1·58) for those aged 13-14 years. In both age groups, we detected no evidence of an association between the use of gas as a cooking fuel and either asthma symptoms or asthma diagnosis.
The use of open fires for cooking is associated with an increased risk of symptoms of asthma and of asthma diagnosis in children. Because a large percentage of the world population uses open fires for cooking, this method of cooking might be an important modifiable risk factor if the association is proven to be causal.
BUPA Foundation, the Auckland Medical Research Foundation, the Health Research Council of New Zealand, the Asthma and Respiratory Foundation of New Zealand, the Child Health Research Foundation, the Hawke's Bay Medical Research Foundation, the Waikato Medical Research Foundation, Glaxo Wellcome New Zealand, the NZ Lottery Board, Astra Zeneca New Zealand, Hong Kong Research Grant Council, Glaxo Wellcome International Medical Affairs.
Abstract The prevalence of respiratory symptoms and risk factors were gathered in four study centres in Western and Central Europe as part of an EU-funded multi-centre study addressing the use of small area methods in air pollution epidemiology (SAVI-AH). The study was carried out in Prague (CZ), Poznan (PL), Huddersfield (UK) and Amsterdam (NL). Prevalences of respiratory symptoms and risk factors between the centres were compared, and associations between risk factors and respiratory symptoms were calculated. Respiratory health was assessed by a self-administered questionnaire, distributed among parents or guardians of schoolchildren between the age of 7 and 11 years. Life-time wheezing and attacks of shortness of breath showed highest prevalences in Huddersfield (30% and 14%, respectively); usual cough showed highest prevalence in Poznan (27%). Differences in prevalence between the centres were found for the potential determinants “age” (due to different age ranges), “gas cooking” (highest in Amsterdam and Poznan), gas/coal heating (lowest in Central European centres), home dampness (highest in Western European centres), disturbance by traffic (highest in urban centres), maternal smoking (highest in Central European centres), family history (highest in Huddersfield) and education (highest in Huddersfield). The prevalence of pets in the home differed only slightly between the study centres. Of the potential deteminants studied, gender, family history of allergic diseases, dampness of the home and, to a lesser extent, passive smoking were important risk factors for life-time prevalence of respiratory symptoms in schoolchildren.
Background:
Adverse respiratory effects in children with asthma are associated with exposures to nitrogen dioxide (NO2). Levels indoors can be much higher than outdoors. Primary indoor sources of NO2 are gas stoves, which are used for cooking by one-third of U.S. households. We investigated the effects of indoor NO2 exposure on asthma severity among an ethnically and economically diverse sample of children, controlling for season and indoor allergen exposure.
Methods:
Children 5-10 years of age with active asthma (n = 1,342) were recruited through schools in urban and suburban Connecticut and Massachusetts (2006-2009) for a prospective, year-long study with seasonal measurements of NO2 and asthma severity. Exposure to NO2 was measured passively for four, month-long, periods with Palmes tubes. Asthma morbidity was concurrently measured by a severity score and frequency of wheeze, night symptoms, and use of rescue medication. We used adjusted, hierarchical ordered logistic regression models to examine associations between household NO2 exposure and health outcomes.
Results:
Every 5-fold increase in NO2 exposure above a threshold of 6 ppb was associated with a dose-dependent increase in risk of higher asthma severity score (odds ratio = 1.37 [95% confidence interval = 1.01-1.89]), wheeze (1.49 [1.09-2.03]), night symptoms (1.52 [1.16-2.00]), and rescue medication use (1.78 [1.33-2.38]).
Conclusions:
Asthmatic children exposed to NO2 indoors, at levels well below the U.S. Environmental Protection Agency outdoor standard (53 ppb), are at risk for increased asthma morbidity. Risks are not confined to inner city children, but occur at NO2 concentrations common in urban and suburban homes.
Objectives:
Evidence for a relationship between gas cooking and childhood respiratory health is inconsistent and few longitudinal studies have been reported. Our aim was to examine the association between gas cooking and the development of respiratory and allergic outcomes longitudinally in a prospective birth cohort study.
Methods:
The Prevention and Incidence of Asthma and Mite Allergy birth cohort study followed children from birth (1996/1997) until age 8. Annual questionnaires were used to document respiratory and allergic symptoms. Allergic sensitisation and bronchial hyper-responsiveness (BHR) were measured at age 8 in subpopulations. A total of 3590 children were included in the present analysis. We used generalised estimating equations and discrete-time hazard models to study the overall and age-specific associations between exposure to gas cooking and the risk of developing respiratory illnesses. Sensitivity analyses of intermittent, always, current and early exposure to gas cooking were conducted.
Results:
Ever gas cooking exposure was associated with nasal symptoms (sneezing, runny/blocked nose without a cold) during the first 8 years of life (OR=1.32, 95% CI 1.09 to 1.59), but not with lower respiratory tract infections, eczema, allergic sensitisation and BHR. Associations with nasal symptoms were similar among children with intermittent, always, current and early exposure. Among girls only, prevalent asthma was associated with ever gas cooking (OR=1.97, 95% CI 1.05 to 3.72).
Conclusions:
Overall, our findings provide little evidence for an adverse effect of exposure to gas cooking on the development of asthma and allergies.
We report analysis of data on outdoor air pollution and respiratory symptoms in children collected in the Czech part of the international Small Area Variations in Air pollution and Health (SAVIAH) Project, a methodological study designed to test the use of geographical information systems (GIS) in studies of environmental exposures and health at small area level. We collected the following data in two districts of Prague: (1) individual data on 3,680 children (response rate 88%) by questionnaires; (2) census-based socio-demographic data for small geographical units; (3) concentrations of nitrogen dioxide (NO2) and sulfur dioxide (SO2) measured by passive samplers in three 2-week surveys at 80 and 50 locations, respectively. We integrated all data into a geographical information system. Modeling of NO2 and SO2 allowed estimation of exposure to outdoor NO2 and SO2 at school and at home for each child. We examined the associations between air pollution and prevalence of wheezing or whistling in the chest in the last 12 months by logistic regression at individual level, weighted least squares regression at small area (ecological) level and multilevel modeling. The results varied by the level of analysis and method of exposure estimation. In multilevel analyses using individual data, odds ratios per 10 μg/m3 increase in concentrations were 1.16 (95% CI = 0.95-1.42) for NO2, and 1.08 (95% CI = 0.97-1.21) for SO2. While mapping of spatial distribution of NO2 and SO2 in the study area appeared valid, the interpolation from outdoor to personal exposures requires consideration.
This review addresses the evidence on the health effects of exposure to emissions of NO² from gas stoves, covering findings of 45 epidemiological studies. These studies had addressed diverse outcome measures, including the risks of acute respiratory illness, decreased pulmonary function, respiratory symptoms and asthma exacerbation. Although most studies have focused on schoolchildren, studies of adults and more recently, prospective studies of infants have also been carried out. The findings have not been consistent across all studies in showing adverse effects. We conclude that the evidence does not support a causal relationship between exposure NO² or use of a gas stove and increased risk for respiratory morbidity at the levels of NO2 typically associated with gas stoves. Some studies do show increased risk for respiratory health effects, however, and the evidence does not support the conclusion that NO2 emitted by gas stoves is risk-free. Further research would be indicated if populations receiving exposures in a range of interest can be identified. Copyright © 1999 John Wiley & Sons, Ltd.
Abstract The indoor environment of 80 houses in the Latrobe Valley, Victoria, Australia was assessed during six visits performed bi-monthly over a period of one year. Children between 7 and 14 years of age residing in the houses were included, resulting in 148 study children, 53 of whom were asthmatic. A respiratory health questionnaire was completed and skin prick tests performed. Significant risk factors for asthma were: exposure to a gas stove (OR=3.15, 95% CI 1.28-7.72), and indoor pets (OR = 2.68, 95% CI 1.07-6.70). Exposure to airborne Aspergillus spores (+10 CFU/m3, OR=1.51, 95% CI 1.05-2.18) was a risk factor for atopy, while exposure to a gas stove (OR=2.32, 95% CI 1.04-5.18) was a risk factor for respiratory symptoms. In conclusion, exposure to gas stoves, fungal spores and pets in the home were identified as statistically significant risk factors for respiratory health in children.
The risk of asthma associated with pets and other indoor exposures has been examined in both cross-sectional and prospective studies of younger children. However, there has been little investigation of the effect of the indoor environment on incident asthma in adolescents.
Risk factors for the development of asthma were examined in a cohort of 3535 Southern California school children with no history of asthma at 1993 entry into the study, who were followed for up to 5 years. Newly diagnosed cases of asthma were identified by yearly interview report. A total of 265 children reported a new diagnosis of asthma during the follow-up period; 163 of these had reported no history of wheeze at baseline. The risk associated with indoor exposures assessed by questionnaire at entry into the study was examined using Cox proportional hazards models.
In children with no history of wheezing, an increased risk of developing asthma was associated with a humidifier (relative risk [RR] = 1.7; 95% confidence interval [CI] = 1.2-2.4), any pet (RR = 1.6; 95% CI = 1.0-2.5), or specifically a dog (RR = 1.4; 95% CI = 1.0-2.0) in the home. An estimated 32% of new asthma cases could be attributed to pets.
We conclude that furry pets are a common and potentially remediable risk factor for new onset asthma in adolescents. Our results suggest that a humidifier in the home may contribute to the onset of asthma in this age group.
Abstract Previous studies have found inconsistent results on the association between asthma in children and gas cooking emissions. We aimed to assess the effects of the long-term exposure to gas cooking on the onset of asthma and respiratory symptoms, focusing on wheezing, in children from two German birth cohorts: LISAplus and GINIplus. A total of 5078 children were followed until the age of 10 years. Asthma, wheezing, gas cooking, and exposure to other indoor factors were assessed through parental reported questionnaires administered periodically. Logistic and multinomial regressions adjusting for potential confounders were performed. The prevalence of asthma and persistent wheezing was higher among children exposed to gas cooking but the results were not statistically significant. Exposure to gas cooking was positively associated (P-value < 0.05) with exposure to other indoor factors (dampness, environmental tobacco smoke, and pets). Our results did not show a statistically significant association between the exposure to gas cooking and children’s respiratory health.
These analyses are consistent with the assumption of no effect of the exposure to low doses of nitrogen dioxide. The strong positive associations found between gas cooking and other indoor factors highlight the importance of considering other indoor factors when assessing health effects of gas cooking. Low-dose exposure to indoor nitrogen dioxide through gas cooking might not contribute to increase the risk of asthma and respiratory symptoms in children.
Because their lungs and immune system are not completely developed, children are more susceptible to respiratory disease and more vulnerable to ambient pollution. We assessed the relation between prenatal and postnatal nitrogen dioxide (NO(2)) levels and the development of lower respiratory tract infections (LRTI), wheezing and persistent cough during the first year of life.
The study population consisted of 352 children from a birth cohort in Valencia, Spain. Prenatal exposure to NO(2), a marker of traffic related air pollution was measured at 93 sampling sites spread over the study area during four different sampling periods of 7 days each. It was modeled for each residential address through land use regression using the empirical measurements and data from geographic information systems. Postnatal exposure was measured once inside and outside each home using passive samplers for a period of 14 days. Outcomes studied were any episode of LRTI during the child's first year of life diagnosed by a doctor (bronchitis, bronchiolitis or pneumonia), wheezing (defined as whistling sounds coming from the chest), and persistent cough (more than three consecutive weeks). Outcomes and potential confounders were obtained from structured questionnaires. Multiple logistic regression was used to identify associations.
The cumulative incidence (CI) at first year of life was 30.4% for LRTI (23.0% bronchiolitis, 11.9% bronchitis and 1.4% pneumonia), 26.1% for wheezing and 6.3% for persistent cough. The adjusted odds ratio (95% confidence interval) per 10μg/m(3) increment in postnatal outdoor NO(2) concentration was 1.40 (1.02-1.92) for persistent cough. We also found some pattern of association with LRTI, bronchiolitis, bronchitis, wheezing and persistent cough in different prenatal periods, although it was not statistically significant.
Our results indicate that exposure to outdoor, but not indoor, NO(2) during the first year of life increases the risk of persistent cough.
Asthma has become the most common, childhood chronic disease in the industrialized world, and it is also increasing in developing regions. There are huge differences in the prevalence of childhood asthma across countries and continents, and there is no doubt that the prevalence of asthma was strongly increasing during the past decades worldwide. Asthma, as a complex disease, has a broad spectrum of potential determinants ranging from genetics to life style and environmental factors. Environmental factors are likely to be important in explaining the regional differences and the overall increasing trend towards asthma's prevalence. Among the environmental conditions, indoor factors are of particular interest because people spend more than 80% of their time indoors globally. Increasing prices for oil, gas and other sources of primary energy will further lead to better insulation of homes, and ultimately to reduced energy costs. This will decrease air exchange rates and will lower the dilution of indoor air mass with ambient air. Indoor air quality and potential health effects will therefore be an area for future research and for gaining a better understanding of asthma epidemics. This strategic review will summarize the current knowledge of the effects of a broad spectrum of indoor factors on the development of asthma in childhood in Western countries based on epidemiological studies. In conclusion, several epidemiological studies point out, that indoor factors might cause asthma in childhood. Stronger and more consistent findings are seen when exposure to these indoor factors is assessed by surrogates for the source of the actual toxicants. Measurement-based exposure assessments for several indoor factors are less common than using surrogates of the exposure. These studies, however, mainly showed heterogeneous results. The most consistent finding for an induction of asthma in childhood is related to exposure to environmental tobacco smoke, to living in homes close to busy roads, and in damp homes where are visible moulds at home. The causing agents of the increased risk of living in damp homes remained uncertain and needs clarification. Exposure to pet-derived allergens and house dust mites are very commonly investigated and thought to be related to asthma onset. The epidemiological evidence is not sufficient to recommend avoidance measures against pet and dust mites as preventive activities against allergies. More research is also needed to clarify the potential risk for exposure to volatile and semi-volatile organic compounds due to renovation activities, phthalates and chlorine chemicals due to cleaning.
Unlabelled:
Health effects of indoor pollution have been investigated overall in urban areas. To compare the potential effect of home air pollutants on asthma in urban and rural houses, two case-control populations, composed of children living in the city (32 asthmatics and 31 controls) and in the countryside (24 asthmatics and 27 controls) were included. During 1 week, nitrogen dioxide, fine particles, and volatile organic compounds (formaldehyde, acetaldehyde, benzene, toluene, ethylbenzene, and xylenes) were assessed at home. Urban dwellings were found to be more polluted than rural ones, with concentrations up to two times higher. In the whole population, exposure to acetaldehyde and toluene was significantly associated with a higher risk of asthma. In the urban population, the association with toluene was significant in children studied during winter, and with toluene, xylenes, and ethylbenzene when cases were restricted to current asthmatics. In rural settings, a relationship between asthma and formaldehyde exposure was observed (OR = 10.7; 95% CI 1.69-67.61). Our findings suggest that daily continuous exposures to pollutants may be implicated in asthma, even in the case of low exposure, as those found in rural areas. Our results could also indicate a specific effect of indoor pollution in the rural environment.
Practical implications:
Everyday exposure to indoor pollution was associated with a higher risk of childhood asthma. These findings suggest that even at low concentrations, pollutants could be implicated in asthma and reinforce the importance of establishing guideline values to improve indoor air quality by limiting sources or by optimizing ventilation. Specific effects could occur in rural environments where pollution differs from urban area.
Inconsistent effects of gas cooking on lung function have been reported. In a previous study from Austria, we demonstrated a significant, though small, reduction of lung function parameters in children living in homes with gas stoves. We used a larger international database to check if this finding can be generalised.
To study the relative impact of cooking with gas on lung function parameters of primary school children in a wide range of geographical settings, we analysed flow and volume data of ∼24,000 children (aged 6–12 yrs) from nine countries in Europe and North America.
Exposure information was obtained by comparable questionnaires and spirometry according to an American Thoracic Society/European Respiratory Society protocol. Linear regressions were used, controlling for individual risk factors and study area. Heterogeneity between study-specific results and mean effects were estimated using meta-analytical tools.
On average, gas cooking reduced lung function parameters. Overall effects were small (-0.1–0.7%) and only significant for forced vital capacity and forced expiratory volume in 1 s. There was some indication that allergic children were more affected by gas cooking.
Under current housing conditions, gas cooking is associated with only small reductions in lung function.
Long-term exposure to air pollution is suspected to cause recurrent wheeze in infants. The few previous studies have had ambiguous results. The objective of this study was to estimate the impact of measured long-term exposure to indoor air pollution on wheezing symptoms in infants. We monitored wheezing symptoms in diaries for a birth cohort of 411 infants. We measured long-term exposure to nitrogen oxides (NO(x)), NO(2), formaldehyde, PM(2.5) and black smoke in the infants' bedrooms and analyzed risk associations during the first 18 months of life by logistic regression with the dichotomous end-point 'any symptom-day' (yes/no) and by standard linear regression with the end-point 'number of symptom-days'. The results showed no systematic association between risk for wheezing symptoms and the levels of these air pollutants with various indoor and outdoor sources. In conclusion, we found no evidence of an association between long-term exposure to indoor air pollution and wheezing symptoms in infants, suggesting that indoor air pollution is not causally related to the underlying disease. Practical Implications Nitrogen oxides, formaldehyde and fine particles were measured in the air in infants' bedrooms. The results showed no evidence of an association between long-term exposure and wheezing symptoms in the COPSAC birth cohort.
Clinicians have difficulty in diagnosing asthma in preschool children with suggestive symptoms.
We sought to develop a clinical asthma prediction score for preschool children who have asthma-like symptoms for the first time.
The Prevalence and Incidence of Asthma and Mite Allergy birth cohort followed 3,963 children for 8 years. Between 0 and 4 years of age, 2,171 (55%) children reported "wheezing," "coughing at night without a cold," or both. In these children possible predictor variables for asthma were assessed at the age respiratory symptoms were first reported. Asthma was defined as wheezing, inhaled steroid prescription, or a doctor's diagnosis of asthma at both age 7 and 8 years of age.
Eleven percent of children with symptoms at 0 to 4 years of age had asthma at 7 to 8 years of age. Eight clinical parameters independently predicted asthma at 7 to 8 years of age: male sex, postterm delivery, parental education and inhaled medication, wheezing frequency, wheeze/dyspnea apart from colds, respiratory infections, and eczema. In 72% of the cases, the model accurately discriminated between asthmatic and nonasthmatic children. A clinical risk score was developed (range, 0-55 points). Symptomatic children with a score of less than 10 points had a 3% risk, whereas children with a score of 30 points or greater had a 42% risk of asthma.
A risk score based on 8 readily available clinical parameters at the time preschool children first reported asthma-like symptoms predicted the risk of asthma at 7 to 8 years of age.
To identify risk factors for asthma in primary school-aged children in New Zealand.
A cross-sectional survey of 10,873 6-7-year-old children in Auckland, Bay of Plenty, Nelson and Christchurch (a response rate of 85.2%). A questionnaire was completed by the parent or care giver.
22.2% of children wheezed in the last 12 months (current wheeze). Maori children were at greater risk of current wheeze compared with European children (adjusted odds ratio (adjOR) = 1.37; 95% confidence interval = 1.18-1.59). Antibiotics and paracetamol used in the first year of life were associated with an increased risk of current wheeze (adjOR = 1.78 (1.56-2.04) and adjOR = 1.31 (1.06-1.61), respectively). Watching television for 5 or more hours per day was associated with an increased risk of current wheeze (adjOR = 1.44 (1.13-1.83)). Milk and egg consumption in the last 12 months was associated with a reduced risk of current wheeze.
This study has identified risk factors for asthma in children aged 6-7 years, although causal pathways cannot be established. These associations have important public health implications if causal.
The aim of this paper is thus to identify, evaluate, and summarize in a systematic fashion all the epidemiological studies that have analyzed the association between exposure to specific indoor air pollutants and respiratory disease among children under the age of five. A search was carried out in the main biomedical bibliographic sources in December 2006 and updated in February 2008. The study period covered 12 years (1996-2007). All the selected papers were carefully read. We focused on studies that analyzed at least one indicator of respiratory health and which included one or more indoor air pollutants in relation to the respiratory health of children under the age of 5. Studies that analyzed passive smoking as the sole source of indoor air pollution were not included. Fourteen studies were considered to be relevant. The most analyzed pollutant was nitrogen dioxide, followed by volatile organic compounds, airborne particulates and other pollutants; phthalates and CO(2). The literature reviewed within our criteria seems to indicate that several indoor pollutants, even at the moderate levels found in the developed countries, could be harmful to the respiratory health of very young children. Future research should focus on conducting more studies, preferably making use of cohorts, with adequate techniques for measuring indoor pollution levels.
A four-year longitudinal study of the prevalence of respiratory symptoms and disease in schoolchildren and related environmental and socio-economic factors is in progress. We report results for the first year of this study (1973). A total of 5758 children aged 6 to 11 years from 28 randomly selected areas of England and Scotland were examined. In an analysis of the effects on health of possible indoor pollutants, boys and girls from homes in which gas was used for cooking were found to have more cough, "colds going to the chest", and bronchitis than children from homes where electricity was used. The girls also had more wheeze if their families used gas for cooking. This "cooking effect" appeared to be independent of the effects of age, social class, latitude, population density, family size, overcrowding, outdoor levels of smoke and sulphur dioxide and types of fuel used for heating. It was concluded that elevated levels of oxides of nitrogen arising from the combustion of gas might be the cause of the increased respiratory illness.
The use of meta-analysis is becoming more common in the medical literature, but it is not common in the environmental literature. Although meta-analysis cannot combine a group of poorly executed, conflicting studies to get an unequivocal answer, there are certain situations where it can be helpful. The inability of studies to produce similar results may be a function of the power of the studies rather than a reflection of their quality. The literature on the effects of nitrogen dioxide on the odds of respiratory illness in children is such an example. Three quantitative methods for the synthesis of this evidence are presented. Although the methods produce slightly different results, the conclusion from all three methods is that the increase in the odds of respiratory illness in children exposed to a long-term increase of 30 micrograms/m3 (comparable to the increase resulting from exposure to a gas stove) is about 20 percent. This estimated increase is not sensitive to the method of analysis.
The effect of indoor nitrogen dioxide on the cumulative incidence of respiratory symptoms and pulmonary function level was studied in a cohort of 1,567 white children aged 7-11 years examined in six US cities from 1983 through 1988. Week-long measurements of nitrogen dioxide were obtained at three indoor locations over 2 consecutive weeks in both the winter and the summer months. The household annual average nitrogen dioxide concentration was modeled as a continuous variable and as four ordered categories. Multiple logistic regression analysis of symptom reports from a questionnaire administered after indoor monitoring showed that a 15-ppb increase in the household annual nitrogen dioxide mean was associated with an increased cumulative incidence of lower respiratory symptoms (odds ratio (OR) = 1.4, 95% confidence interval (95% Cl) 1.1-1.7). The response variable indicated the report of one or more of the following symptoms: attacks of shortness of breath with wheeze, chronic wheeze, chronic cough, chronic phlegm, or bronchitis. Girls showed a stronger association (OR = 1.7, 95% Cl 1.3-2.2) than did boys (OR = 1.2, 95% Cl 0.9-1.5). An analysis of pulmonary function measurements showed no consistent effect of nitrogen dioxide. These results are consistent with earlier reports based on categorical indicators of household nitrogen dioxide sources and provide a more specific association with nitrogen dioxide as measured in children's homes.
To investigate the influence of indoor air quality on respiratory health, a questionnaire-based study of 17,962 Canadian schoolchildren in kindergarten through grade 2 was carried out in 1988. The present report focuses on associations between several indoor environmental factors and childhood asthma. Increased reports of physician-diagnosed asthma were significantly associated (p less than 0.001) with exposure to environmental tobacco smoke (OR = 1.4), living in a damp home (OR = 1.5), the use of gas for cooking (OR = 2.0) and the use of a humidifier (OR = 1.7). Wheezing without a diagnosis of asthma also was associated (p less than 0.01) with environmental tobacco smoke (OR = 1.4, home dampness (OR = 1.6) and humidifier use (OR = 1.4), but not with gas cooking. Thus, several modifiable risk factors for respiratory illness may exist in Canadian homes. Further research is required to determine the nature of these cross-sectional observations.
The aim of the study was to seek for a possible association between the incidence of upper respiratory tract infections and air temperature and humidity in the home.
Recordings of temperature and relative humidity were made in living rooms and children's bedrooms over a six month period and related to incidence of upper respiratory tract infection.
The study was carried out in one general practice of 10,000 patients.
297 children aged 24-59 months were studied, selected in random order from the practice age-sex register.
Temperature and humidity recordings were made with thermohygrograph recorders over six days. Upper respiratory tract infections were recorded (a) retrospectively over the previous 12 months, and (b) during the study period. Past history of acute otitis media and recent family history of respiratory infection were also obtained. No significant association was found between the variables, although the bedrooms of children with reported upper respiratory tract infections were cooler overnight than those of non-infected children (mean difference 0.8 degrees C, 95% confidence limits 0.7 degrees C). No association was found between reported or recorded upper respiratory tract infections and age or type of home, family size, level of occupancy, social class, or smoking habits. Only 15 children (5%) were identified by their parents as having had asthma, but 58 (19.5%) had had a "wheezy chest". A greater proportion of children who wheezed slept in cooler bedrooms, had gas fires rather than central heating, and had more smokers in the house.
No association between upper respiratory tract infection and domestic temperature or humidity levels could be shown in this study. Since dampness is repeatedly presented as a health risk, further study is required.
Hosein H R (Occupational Health Unit, Faculty of Medicine, University of Toronto, 150 College Street, Toronto, Ontario, M4S 1A1, Canada), Corey Pand Robertson J Mc D. The effect of domestic factors on respiratory symptoms and FEV1. International Journal of Epidemiology 1989, 18: 390–396.
This study was conducted to determine whether indoor air pollution factors affected respiratory function and symptoms in 1357 non-smoking Caucasian children. Interviews were conducted to determine: exposure to pets and to gases, vapours and dusts from hobbies; the use of gas stoves; fireplaces, air conditioners and humidifiers; type of heating systems; and the number of residents, and the number of smokers in the home. The forced expiratory volume in one second (FEV1) was obtained from maximum expiratory flow volume curves, and symptoms from the application of a standardized questionnaire.
Indoor pets and the use of fireplaces and humidifiers had no consistent relationships with FEV1 when considered individually or in combination with the other factors. Hobbies, the use of gas stoves, the absence of air conditioning, the use of hot water heating, crowded homes, and the presence of smokers in the home all had negative relationships with FEV1. The largest effect on lung function was observed in children from homes with hot water heating systems, whereas the smallest effect was observed in children with smokers in the home. Children who lived in homes with hot water heating systems with no air conditioning had mean FEV1 of up to 0.4 litres lower than did their counterparts who lived in homes with forced air heating and air conditioning.
Pets, heating systems, cooking fuel, crowding and passive smoking showed no consistent effects on the reporting of any of the symptoms. Girls who were exposed to the emissions from indoor hobbies reported more phlegm, wheeze and dyspnoea.
This paper examines eight published reviews each reporting results from several related trials. Each review pools the results from the relevant trials in order to evaluate the efficacy of a certain treatment for a specified medical condition. These reviews lack consistent assessment of homogeneity of treatment effect before pooling. We discuss a random effects approach to combining evidence from a series of experiments comparing two treatments. This approach incorporates the heterogeneity of effects in the analysis of the overall treatment efficacy. The model can be extended to include relevant covariates which would reduce the heterogeneity and allow for more specific therapeutic recommendations. We suggest a simple noniterative procedure for characterizing the distribution of treatment effects in a series of studies.
The influence of indoor nitrogen-dioxide exposure on respiratory symptoms of schoolchildren was investigated in a case-control study. The election method used was useful in obtaining symptomatic children, but insufficient in defining cases and controls without additional information. No relationship between indoor NO2 and respiratory symptoms was found. Bias may have been present, especially because of the high mobility of the study population. Attempts to estimate historical exposure were inaccurate. Therefore the results do not exclude that an association between indoor NO2 and respiratory symptoms exists.
As part of a longitudinal study of the respiratory health effects of indoor and outdoor air pollutants, pulmonary function, respiratory illness history, and symptom history were recorded at 2 successive annual examinations of 10,106 white children living in 6 cities in the United States. Parental education, illness history, and smoking habits also were recorded, along with the fuel used for cooking in the child's home. Maternal cigarette smoking was associated with increases of 20 to 35% in the rates of 8 respiratory illnesses and symptoms investigated, and paternal smoking was associated with smaller but still substantial increases. Illness and symptom rates were linearly related to the number of cigarettes smoked by the child's mother. Illness rates were higher for children of current smokers than for children of ex-smokers. The associations between maternal smoking status and childhood respiratory illnesses and symptoms were reduced but not eliminated by adjustment for parental illness history. Levels of forced expiratory volume in one second (FEV1) were significantly lower for children of current smokers than for children of nonsmokers at both examinations and highest for children of ex-smokers. Levels of forced vital capacity (FVC) were lower for children of nonsmokers than for children of current smokers at both examinations, but the difference was statistically significant only at the first examination. Both the increase in mean FVC and the decrease in mean FEV1 among children of current smokers were linearly related to daily cigarette consumption. None of the respiratory illnesses and symptoms studied was significantly associated with exposure to gas cooking in the child's home.(ABSTRACT TRUNCATED AT 250 WORDS)
The respiratory health of a large group of Arizona school children who have been exposed to indoor pollutants--tobacco smoke and home cooking fumes--is reported. A significant relationship was found between parental smoking and symptoms of cough, wheeze, and sputum production. Also, children in homes where gas cooking fuel was used had higher rates of cough than children in homes where electricity was used. No differences in pulmonary function or yearly lung growth rates occurred among subjects grouped by exposure to tobacco smoke or cooking fuel. Thus, parental smoking and home cooking fuel affected cross-sectional respiratory symptom rates in a large group of Arizona school children. Study of pulmonary function, however, revealed no lung function or lung growth effects during 4 yr of study.
To investigate the effects of the home environment on the risk of severe asthma during adolescence.
A questionnaire based case-control study drawn from a cross sectional survey of allergic diseases among secondary school pupils in Sheffield in 1991.
763 children whose parents had reported that over the previous 12 months they had suffered either 12 or more wheezing attacks or a speech limiting attack of wheeze. A further 763 children were frequency matched for age and school class to act as controls. Analysis was restricted to 486 affected children and 475 others born between 1975 and 1980 who had lived at their present address for more than three years.
Independent associations with severe wheeze were seen for non-feather bedding, especially foam pillows (odds ratio 2.78; 95% confidence interval 1.89 to 4.17), and the ownership of furry pets now (1.51; 1.04 to 2.20) and at birth (1.70; 1.20 to 2.40). These estimates were derived from subjects whose parents denied making changes in the bedroom or avoiding having a pet because of allergy. Parental smoking, use of gas for cooking, age of mattress, and mould growth in the child's bedroom were not significantly associated with wheezing.
Either our study questionnaire failed to detect the avoidance or removal of feather bedding by allergic families or there is some undetermined hazard related to foam pillows. Synthetic bedding and furry pets were both widespread in this population and may represent remediable causes of childhood asthma.
Exposure to various factors from the indoor environment on respiratory health of 470 Dutch primary school children was studied. We investigated which of the factors, such as home dampness, passive smoking, unvented kitchen geysers, or pets, affected children's respiratory health the most, and whether airway sensitivity to these indoors exposures differed between boys and girls. Information on respiratory morbidity and characteristics of the housing was obtained by a written questionnaire, completed by the parents of the children. Lung function of the children was measured at school, by forced oscillation technique (FOT) and spirometry. In boys, all investigated lung function parameters were significantly affected by exposure to passive smoking during the child's entire life. Although mostly nonsignificant, all of the reported asthma-like symptoms were related especially to maternal smoking, with a trend of a dose-response relationship. Furthermore, damp stains (P < 0.05) and mold growth (ns) were associated with chronic cough and with small but significant impairments in part of the lung function parameters. No consistent patterns were observed with unvented kitchen geysers and pets. Although passive smoking (cumulative dose) in girls was also associated with lung function impairments, the effects were smaller than those in boys and not all significant. Associations between the asthma-like symptoms and the dose of maternal and paternal smoking also were less consistent. Furthermore, no associations were found with the dampness indicators and with pets, but unvented kitchen geysers were significantly related to impairments in some of the impedance indices. This study shows detrimental effects of several indoor factors on the prevalence of chronic respiratory symptoms and lung function in children, which are most pronounced for passive smoking, and somewhat less pronounced for dampness and the presence of unvented kitchen geysers. Airway sensitivity to these exposures appeared to be higher in boys than in girls.
The purpose of this study was to examine possible links between respiratory conditions among schoolchildren and exposure to environmental tobacco smoke and other home and community exposures. More than 8,000 second- and fifth-grade schoolchildren who lived in three towns along the Israeli coast were administered pulmonary function tests, and their parents completed standardized health questionnaires. The prevalence of the most reported respiratory conditions was found to be higher, some of them significantly so, among children whose fathers or mothers were smokers, compared with children of non-smoking parents. Most respiratory conditions were reported significantly more often for children who were growing up in medium- and highly polluted communities than for children from low-polluted areas. House heating with kerosene or gas was seldom associated with higher prevalence of respiratory conditions among children. No consistent r trend of reduced pulmonary function tests was associated with exposure to environmental tobacco smoke, with community pollution, or with house heating pollution. In conclusion, exposure of schoolchildren to their parents' cigarette smoke and to community air pollution is associated with higher prevalence of respiratory conditions, whereas house heating does not appear to be a public health problem in Israel.
This study investigated the relationship between indoor air quality and the prevalence of respiratory symptoms in South Australian preschool children.
Data were collected from 14,124 families with a child aged 4 years 3 months to 5 years of age. This sample represents 73% of the targeted State preschool population. At the time of a routine preschool health check, parents completed a questionnaire regarding: their child's respiratory health and place of residence (postcode), parental smoking, type of fuel used for cooking and heating and method used for home cooling.
For preschool children residing in the greater Adelaide region, logistic regression analyses found that having a natural gas stove compared to an electric stove was significantly associated with increased prevalence rates for: (i) asthma (odds ratio [OR] 1.24); (ii) wheezing in the preceding 12 months (OR 1.16); excessive colds (OR 1.14); and hay fever (OR 1.13). The use of a liquid petroleum gas stove compared to an electric stove was not associated with any respiratory symptoms. The use of a flueless gas heater compared to other forms of heating was significantly associated with increased prevalence rates for dry cough (OR 1.26), ever having wheezed (OR 1.15) and wheezing in the preceding 12 months (OR 1.18). The use of a wood fire/heater compared to other forms of heating was significantly associated with a reduced prevalence rate for dry cough (OR 0.84) and ever having wheezed (OR 0.82). Parental smoking was significantly associated with increased prevalence rates for bronchitis (OR 1.21) and ever having wheezed (OR 1.24). The form of home cooling used was not associated with prevalence rates, after accounting for geographic location. Socio-economic status (postcode level) was not generally associated with prevalence rates.
These results suggest that respiratory symptom prevalence is related to the fuel used for cooking and heating and parental smoking. Prospective investigation regarding indoor air quality and respiratory symptoms is required.
Nitrogen dioxide is an oxidant gas that contaminates outdoor air and indoor air in homes with unvented gas appliances. A prospective cohort study was carried out to test the hypothesis that residential exposure to NO2 increases incidence and severity of respiratory illnesses during the first 18 months of life. A cohort of 1,205 healthy infants from homes without smokers was enrolled. The daily occurrence of respiratory symptoms and illnesses was reported by the mothers every 2 wk. Illnesses with wheezing or wet cough were classified as lower respiratory tract. Indoor NO2 concentrations were serially measured with passive samplers place in the subjects' bedrooms. In stratified analyses, illness incidence rates did not consistently increase with exposure to NO2 or stove type. In multivariate analyses that adjusted for potential confounding factors, odds ratios were not significantly elevated for current or lagged NO2 exposures, or stove type. Illness duration, a measure of illness severity, was not associated with NO2 exposure. The findings can be extended to homes with gas stoves in regions of the United States where the outdoor air is not heavily polluted by NO2.
In a case-control study carried out in Montréal, Québec, Canada, between 1988 and 1990, indoor environmental factors were studied in relation to the incidence of asthma among 3- and 4-year-old children. Cases (n = 457), whose parents were recruited at a hospital emergency room, were children who had a first-time diagnosis of asthma (International Classification of Diseases, Ninth Revision, code 493) made by a pediatrician. Controls (n = 457) were chosen from family allowance files and were matched with case children on age and census tract. A telephone interview was administered to the children's parents. A 20% feasibility subsample was chosen to wear a nitrogen dioxide monitoring badge during a 24-hour period. Multiple conditional logistic regression analysis showed that after personal susceptibility factors were controlled for, the following were independent risk factors for asthma: the mother's heavy smoking (odds ratio (OR) = 2.77, 95% confidence interval (CI) 1.35-5.66), use of a humidifier in the child's room (OR = 1.89, 95% CI 1.30-2.74), and the presence of an electric heating system in the home (OR = 2.27, 95% CI 1.42-3.65). The presence of other smokers in the home was not quite significant (OR = 1.82, 95% CI 0.98-3.38). A history of pneumonia, the absence of breast feeding, and a family history of asthma were also significant risk factors. In a separate unmatched multivariate analysis of subjects who had worn the nitrogen dioxide badge, there was a dose-response relation between nitrogen dioxide (in parts per billion) and asthma. These results confirm the role of susceptibility factors in asthma and show that indoor environmental factors contribute to the incidence of asthma.
Indoor risk factors for physician-diagnosed asthma and wheezing in the past 12 months without previous asthma diagnosis were assessed in a survey of parents of 5-9-year-old Seattle primary school students. Among the 925 respondents, 106 (11%) reported a physician diagnosis of asthma, 66 (7%) had wheezing without diagnosis, and 753 (82%) were asymptomatic. After adjusting for age, sex, gender, ethnicity, medical history, socioeconomic status (SES) and parental asthma status, an increased risk of physician diagnosis of asthma was associated with household water damage, the presence of one or more household tobacco smokers, and at least occasional environmental tobacco smoke (ETS) exposure. Similarly, an increased risk of wheezing in the past 12 months among children without diagnosed asthma was associated with household water damage, presence of one or more household tobacco smokers, and occasional or more frequent ETS exposure. No increased risk of either condition was associated with gas, wood, or kerosene stove use, household mold, basement water, or wall/window dampness. Similarities in the indoor risk factors patterns between diagnosed asthma and wheezing without diagnosis suggested a similar etiology of these two conditions. The slightly higher association between ETS and asthma may indicate that parents of diagnosed asthmatics were more conscious of ETS, and were more likely to prohibit household smoking by resident smokers. Future research is needed to quantify which aspects of household water damage are related to respiratory illness.
In this cross-sectional postal study, the authors measured nitrogen dioxide levels inside infants' bedrooms and outside their homes. During the 2-wk monitoring period, the authors investigated the association between nitrogen dioxide levels and 20 infant symptoms. The subjects were 1,200 women who had infants aged 3-12 mo. Median levels of indoor and outdoor nitrogen dioxide were 6.8 and 12.6 ppb, respectively. Environmental factors that were associated significantly with indoor levels were gas cooking, cigarette smoking, reported traffic levels, and presence of a kerosene heater; use of a cooker hood was associated negatively with indoor nitrogen dioxide levels. There was no evidence for any short-term significant association between prevalence of respiratory symptoms and nitrogen dioxide levels. Diarrhea, the only symptom associated significantly and positively with indoor nitrogen dioxide levels, had unadjusted and adjusted odds ratios of 1.48 (95% confidence interval: 1.13, 1.95) and 1.38 (1.11, 1.70), respectively. This association is discussed in terms of a proposed mechanism with nitric oxide. No association between a gas cooker in the home and diarrhea was found. The association between diarrhea and nitrogen dioxide level might have been a chance finding; the authors investigated 20 symptoms, and at least 1 was expected to be significant at the .05 level. The finding, however, was similar to that reported in a previous study in which a gas cooker was a proxy for nitrogen dioxide exposure.
Prevalence surveys of asthma and/or wheezing among all children aged between 7 1/2 and 8 1/2 attending state and private schools in the London Borough of Croydon were conducted in February 1978 and February 1991. Two population based case-control studies drawn from the survey responders were used to investigate the association between childhood wheeze and characteristics of the home environment and to assess whether changes in these characteristics between 1978 and 1991 may have contributed to an increase in the population prevalence of wheeze among school children.
Information on exposure to potential indoor environmental risk factors was obtained from parents by home interview and compared between cases-that is, children with frequent (> or = 5) or in-frequent (1-4) attacks of asthma or wheezing in the past 12 months- and controls, with adjustment for study. Changes in exposure over time were assessed by comparing control groups.
Between 1978 and 1991 the population prevalence odds of wheeze increased by 20% (OR 1.20; 95% CI 1.04 to 1.39). Change in parental smoking, gas cooking, pet ownership, and central heating did not appear to explain the rise. Use of non-feather pillows was positively associated with childhood wheeze even after adjusting for other risk factors and after re-coding from non-feather to feather cases thought to have changed pillow in response to symptoms (OR 1.54; 95% CI 1.13 to 2.10). The proportion of control children reportedly using non-feather pillows was 44% in 1978 and 67% in 1991.
Increased use of non-feather pillows was the only domestic indoor exposure studied which appeared to explain a modest rise in prevalence of wheeze from 1978 to 1991. Our analysis attempts to address behavioural change in response to the child's symptoms but an artifact arising from lifelong avoidance of feather bedding in atopic families cannot be entirely discounted.