Article

Effectiveness of Air Purifier on Health Outcomes and Indoor Particles in Homes of Children with Allergic Diseases in Fresno: A Pilot Study

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Abstract

Objective: Epidemiologic studies indicate that indoor air pollution is correlated with morbidity caused by allergic diseases. We evaluated the effectiveness of reducing the levels of indoor fine particulate matter < 2.5 micrometer diameter (PM2.5) in Fresno, California using air purifiers on health outcomes in children with asthma and/or allergic rhinitis. Methods: The active group (with air purifiers) and the control group consisted of eight houses each. Air purifiers were installed in the living rooms and bedrooms of the subjects in the active group during the entire 12-week study duration. Childhood asthma control test, peak flow rate monitoring, and nasal symptom scores were evaluated at weeks 0, 6, and 12. Results: At 12 weeks, the active group showed a trend toward an improvement of childhood asthma control test scores and mean evening peak flow rates, whereas the control group showed deterioration in the same measures. Total and daytime nasal symptoms scores significantly reduced in the active group (p = 0.001 and p = 0.011, respectively). The average indoor PM2.5 concentrations reduced by 43% (7.42 to 4.28 μg/m(3)) in the active group (p = 0.001). Conclusions: Intervention with air purifiers reduces indoor PM2.5 levels with significant improvements in nasal symptoms in children with allergic rhinitis in Fresno.

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... Some studies also showed that air filters can have a beneficial effect on respiratory symptoms in patients with asthma. 14,15 The impact of PM is prominent in patients with chronic respiratory diseases, such as chronic obstructive pulmonary disease (COPD) and asthma. 16 Many recent studies evaluated the effect of interventions on PM concentration, particularly the use of air filters on respiratory outcomes. ...
... Afterward, 7 studies were included in the qualitative analysis. Six of the studies included were randomized controlled trials conducted on asthmatic patients, 14,15,[24][25][26][27] and one was a randomized cross-over study conducted on COPD patients. 18 Six studies were conducted in the US 14,15,[24][25][26][27] and one was conducted in China. ...
... Six of the studies included were randomized controlled trials conducted on asthmatic patients, 14,15,[24][25][26][27] and one was a randomized cross-over study conducted on COPD patients. 18 Six studies were conducted in the US 14,15,[24][25][26][27] and one was conducted in China. 18 The characteristics of the studies are described in Table 1. ...
Article
Purpose: Exposure to particulate matter (PM) is a key public health issue, but effective intervention has not yet been established. A systematic literature review and meta-analysis has been conducted to assess the relationship between the use of air filters, one of the most commonly studied interventions, and respiratory outcomes in patients with chronic respiratory diseases. Methods: We systematically reviewed intervention studies on PM using PubMed, EMBASE, and Cochrane databases up to September 2019. Studies that included data on PM concentration changes and respiratory symptoms or lung function in patients with respiratory diseases were eligible for inclusion. Effect estimates were quantified separately using the random-effects model. Results: Six studies were included in the quantitative analysis. Air filter use reduced indoor PM2.5 by 11.45 µg/m 3 (95% confidence interval [CI], 6.88, 16.01 µg/m 3). Air filter use was not associated with improvements in respiratory symptoms in 5 of the 6 studies or significant changes in the predicted forced expiratory volume in one second (FEV1) (mean change, −1.77%; 95% CI, −8.25%, 4.71%). Air filter use was associated with improved peak expiratory flow rate by 5.86 (95% CI, 3.5, 8.19 of standardized difference). Conclusions: The findings of this systematic review suggest that air filters may reduce indoor PM and increase peak expiratory rate in asthmatic patients. However, most studies showed no significant effects of air filters on respiratory symptoms or FEV1. Further studies in regions with high-density PM may provide additional information on this issue. Trial Registration: PROSPERO Identifier: CRD42020156258
... In countries outside Japan, air purification has been reported to reduce the indoor concentrations of PM 2.5 and allergens, alleviating the symptoms of people with asthma [17][18][19][20][21]. Moreover, air purification has been shown to improve cardiovascular and pulmonary functions in elderly individuals [22]. ...
... The results presented here indicated that there was no significant reduction in indoor air pollutant levels by air purification, and changes in the study subjects' pulmonary function were not observed. Previous reports showed that air purification decreased indoor PM2.5 concentrations and contributed to improved pulmonary function [18,25]. However, studies conducted in elderly individuals reported no association between air purification and improved pulmonary function [23,24]. ...
... Weichenthal et al. reported that a decrease in the PM2.5 concentration achieved by air purification was associated with statistically significant improvements in FEV 1.0 and PEF [25]. Park et al. examined the effects of air purification in children with asthma and/or allergic rhinitis, and the results demonstrated that the use of air purifiers reduced indoor PM2.5 concentrations and improved the evening PEF [18]. These results are not entirely consistent with our present findings. ...
Article
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Air purifiers have become popular among ordinary families. However, it remains controversial whether indoor air purification improves the respiratory health of healthy adults. A randomized crossover intervention study was conducted with 32 healthy individuals. The subjects were categorized into two groups. One group continuously used true air purifiers, and the other followed with sham air purifiers for 4 weeks. Following this first intervention, all the subjects underwent a 4-week washout period and continued with the second 4-week intervention with the alternate air purifiers. We collected fine particulate matter (PM) ≤ 2.5 µm in aerodynamic diameter (PM2.5), coarse particulate matter between 2.5 and 10 µm in aerodynamic diameter (PM10–2.5) and ozone (O3). The subjects’ pulmonary function and fractional exhaled nitric oxide (FeNO) were measured during the study period. The indoor PM2.5 concentrations decreased by 11% with the true air purifiers compared to those with sham air purifiers. However, this decrease was not significant (p = 0.08). The air purification did not significantly improve the pulmonary function of the study subjects. In contrast, an increase in the indoor PM10–2.5 and O3 concentration led to a significant decrease in the forced expiratory volume in one second (FEV1.0)/forced vital capacity (FVC) and maximal mid-expiratory flow (MMEF), respectively. In conclusion, air purification slightly improved the indoor PM2.5 concentrations in ordinary homes but had no demonstrable impact on improving health.
... Some studies also showed that air filters can have a beneficial effect on respiratory symptoms in patients with asthma. 14,15 The impact of PM is prominent in patients with chronic respiratory diseases, such as chronic obstructive pulmonary disease (COPD) and asthma. 16 Many recent studies evaluated the effect of interventions on PM concentration, particularly the use of air filters on respiratory outcomes. ...
... Afterward, 7 studies were included in the qualitative analysis. Six of the studies included were randomized controlled trials conducted on asthmatic patients, 14,15,[24][25][26][27] and one was a randomized cross-over study conducted on COPD patients. 18 Six studies were conducted in the US 14,15,[24][25][26][27] and one was conducted in China. ...
... Six of the studies included were randomized controlled trials conducted on asthmatic patients, 14,15,[24][25][26][27] and one was a randomized cross-over study conducted on COPD patients. 18 Six studies were conducted in the US 14,15,[24][25][26][27] and one was conducted in China. 18 The characteristics of the studies are described in Table 1. ...
Article
Full-text available
Purpose Exposure to particulate matter (PM) is a key public health issue, but effective intervention has not yet been established. A systematic literature review and meta-analysis has been conducted to assess the relationship between the use of air filters, one of the most commonly studied interventions, and respiratory outcomes in patients with chronic respiratory diseases. Methods We systematically reviewed intervention studies on PM using PubMed, EMBASE, and Cochrane databases up to September 2019. Studies that included data on PM concentration changes and respiratory symptoms or lung function in patients with respiratory diseases were eligible for inclusion. Effect estimates were quantified separately using the random-effects model. Results Six studies were included in the quantitative analysis. Air filter use reduced indoor PM2.5 by 11.45 µg/m3 (95% confidence interval [CI], 6.88, 16.01 µg/m3). Air filter use was not associated with improvements in respiratory symptoms in 5 of the 6 studies or significant changes in the predicted forced expiratory volume in one second (FEV1) (mean change, −1.77%; 95% CI, −8.25%, 4.71%). Air filter use was associated with improved peak expiratory flow rate by 5.86 (95% CI, 3.5, 8.19 of standardized difference). Conclusions The findings of this systematic review suggest that air filters may reduce indoor PM and increase peak expiratory rate in asthmatic patients. However, most studies showed no significant effects of air filters on respiratory symptoms or FEV1. Further studies in regions with high-density PM may provide additional information on this issue.
... The use of HEPA filtration (typically equivalent to MERV 16) in living rooms and/or bedrooms has been shown to reduce indoor residential PM 2.5 concentrations between 40% and 72% versus baseline, control or outdoor levels [166][167][168][169][170]. The efficiency of these filters to reduce PM 2.5 has been shown to decrease over time [171]. ...
... Studies assessing whether gas-phase filtration or ionisers in air cleaners have a positive effect on human health are also scarce. A small study investigated the use of HEPA filter air cleaners with activated carbon in the living room and bedroom for 12 weeks and, while PM 2.5 levels were reduced by 43% and there was a significant improvement in peak exploratory flow (suggestive of improved asthma control) attributable to the cleaner, there was no evidence that the activated carbon was itself effective [169]. ...
Article
Full-text available
As global awareness of air pollution rises, so does the imperative to provide evidence-based recommendations for strategies to mitigate its impact. While public policy has a central role in reducing air pollution, exposure can also be reduced by personal choices. Qualified evidence supports limiting physical exertion outdoors on high air pollution days and near air pollution sources, reducing near-roadway exposure while commuting, utilising air quality alert systems to plan activities, and wearing facemasks in prescribed circumstances. Other strategies include avoiding cooking with solid fuels, ventilating and isolating cooking areas, and using portable air cleaners fitted with high efficiency particulate air filters. We detail recommendations to assist providers and public health officials when advising patients and the public regarding personal-level strategies to mitigate risk imposed by air pollution, while recognising that well-designed prospective studies are urgently needed to better establish and validate interventions that benefit respiratory health in this context.
... 8 It has been shown that the use of an air purifier equipped with a high-efficiency particulate air (HEPA) filter to reduce indoor air pollution helps control allergic diseases. A number of reports have indicated that air purifiers are beneficial for patients with allergic rhinitis (AR), [9][10][11] atopic dermatitis, 12 and asthmatic children. 13,14 In addition, air purifiers are credited with removing pollen, fungal spores, 15 house dust-mite (HDM) allergens, 10 and dog allergens. ...
... Sample size was calculated using PASS v12 (NCSS LLC, Kaysville, UT, USA). A sample size of 22 for each of the two groups (1:1 allocation, 5% expected drop-out rate) was determined to achieve an 80% power, assuming a change in total nasal symptom score of 2.5 (as in a previous study), 9 standard deviations of 2.3 (group 1) and 1.4 (group 2), a significance level (alpha) of 0.050, and the use of a two-sided two-sample unequal-variance t-test. For group comparisons, SPSS Statistics v23.0 for Windows (IBM Corp., Armonk, NY, USA) and SAS v9.4 (SAS Inc., Cary, NC, USA) were used. ...
Article
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Purpose: Exposure to particulate matter (PM) is a well-known risk factor in the triggering and exacerbation of allergic airway disease. Indoor environments, where people spend most of their time, are of utmost importance. To assess the effects of air purifiers [equipped with high-efficiency particulate air (HEPA) filters] on allergic rhinitis (AR) in adult patients, we performed a multicenter, randomized, double-blind, and placebo-controlled study. Materials and methods: Patients with house dust mite (HDM)-induced AR were randomly assigned to either active or mockup (placebo) air-purification groups. Two air purifiers (placed in living room and bedroom) were operated for 6 weeks in each home environment. The primary study endpoint was to achieve improvement in AR symptoms and medication scores. Secondary endpoints were to achieve improvement in the quality of life (QoL) and visual analog scale (VAS) scores, as well as in the indoor (bedroom and living room) concentrations of PM2.5 and PM10. Results: After 6 weeks of air purifier use, medication scores improved significantly in the active (vs. placebo) group, although subjective measures (symptoms, VAS, and QoL scores) did not differ. Bedroom PM2.5 concentrations initially exceeded living room or outdoor levels, but declined (by up to 51.8%) following active purifier operation. Concentrations of PM2.5 in living room and PM10 in bedroom and living room were also significantly reduced through active purification. Conclusion: The use of air purifiers with HEPA filters significantly reduced medication requirements for patients with HDM-induced AR and significantly lowered indoor PM2.5 concentrations, regardless of room placement. Active intervention to reduce household air pollutants may help improve allergic airway disease (clinicaltrials.gov NCT03313453).
... Another study in the Annapolis Valley, Nova Scotia, tested the air purifiers' effectiveness to remove wood smoke produced by woodstove/wood furnace, from within homes during the winter. e study revealed a 52% reduction in PM 2.5 [24]. ...
... An intervention study at homes in Fresno, California, evaluated the effectiveness of reducing the levels of indoor air pollutants like PM 2.5 using air purifiers to improve the health outcomes in children with asthma and allergic rhinitis. At 12 weeks, the intervention group showed the improvement in Asthma Control Test scores, whereas the control group had deterioration in the same measures [24]. Another study which examined the association of exposure to secondhand smoke (SHS) with wheezing and asthma in children showed that those exposed to SHS are 1.5 times more likely to be diagnosed with asthma or wheezing compared to unexposed children [15,25]. ...
Article
Full-text available
Few studies have investigated household interventions to enhance indoor air quality (IAQ) and health outcomes in relatively low-income communities. This study aims to examine the impact of the combined intervention with asthma education and air purifier on IAQ and health outcomes in the US-Mexico border area. An intervention study conducted in McAllen, Texas, between June and November 2019 included 16 households having children with asthma. The particulate matter (PM2.5) levels were monitored in the bedroom, kitchen, and living room to measure the IAQ for 7 days before and after the intervention, respectively. Multiple surveys were applied to evaluate changes in children's health outcomes. The mean PM2.5 levels in each place were significantly improved. Overall, they significantly decreased by 1.91 μg/m3 on average (p
... A crossover study in Denmark reported a reduction in PM 2.5 of 54.5% (median value) in locations using HEPA filtration (Spilak et al., 2014). A 43% reduction in PM 2.5 was shown in an intervention study in the United States when HEPA filtration was used (Park et al., 2017). In a modelling study by Fisk and Chan (Fisk & Chan, 2017a) a number of scenarios were simulated, including using portable air purifiers in homes without forced air systems, which closely resembles many of the dwellings monitored in the work presented here. ...
... However, past research was, for the most part, not inclusive of typical ambient air quality conditions and healthy adults. Rather, outdoor pollution events, such as wildfires, and occupants with specific health conditions, like lung disease, and children were the focus of the studies (Brugge et al., 2017;Maestas et al., 2019;Park et al., 2017;Spilak et al., 2014;Vyas et al., 2016;Weichenthal et al., 2013). ...
Article
Full-text available
One of the most widely available technologies to clean the air in homes of particulate matter of less than 2.5 µm in diameter (PM2.5), known to have negative health impacts, are portable home air purifiers (HAPs). This paper presents research which (1) explored the effectiveness of HAPs in real-world conditions in 57 homes in three European cities; (2) examined if HAPs affect users’ perceptions of the indoor air quality (IAQ) at home; and (3) considered the motivations for occupants’ operation of HAPs. Results from this study found that PM2.5 concentrations in bedrooms were reduced by 45% to 69%; perceptions of IAQ were not correlated with measured high PM2.5 levels; occupants reported the HAPs to have a ‘cooling’ effect, which may explain why the predominant driver of HAP use was thermal comfort, rather than IAQ, in all three cities. The latter finding was supported by a statistically significant increase in the probability of HAP use with increasing indoor temperatures. If the operation of HAPs can be managed, or fully automated, to reflect indoor air pollution levels rather than thermal conditions, better pollutant reduction would be feasible and their use to reduce PM2.5 may help mitigate the negative health effects of exposure whilst at home.
... 24 However, studies reporting on the impact of HEPA filtration on health outcomes have had varied results. [25][26][27][28][29][30][31][32][33] While there were statistically significant benefits of particle filtration on health outcomes for those with asthma and allergic rhinitis, these improvements were defined as "modest." 34,35 It should be noted, however, that a recent study by Jia-Ying et al reported improvements in allergic rhinitis symptoms by using HEPA filtration. ...
... The cutoff point for "well-controlled" asthma is with asthma and/or allergic rhinitis in a highly polluted city. 25 Eight participants were given a HEPA air purifier, while the participants in the control group did not have an air purifier. Their results demonstrated a trend toward improvement in Asthma Control Test (ACT) scores and mean peak flow in the HEPA filter group, but these trends did not reach statistical significance, possibly due to the small size of the study population. ...
Article
Traffic‐related airborne particles are associated with asthma morbidity. The aim of this study was to assess the impact of a high‐efficiency particulate air (HEPA) filtration on the concentrations of traffic particles and the resultant effect on children with asthma. Forty‐three children with asthma were enrolled in this double‐blind, placebo‐controlled crossover design. A HEPA air cleaner or a placebo “dummy” was placed in participants’ homes for four weeks, interrupted by a one‐month washout period, before crossing over to the other treatment arm for four weeks. Air sampling and health outcomes, including asthma control (ACQ) and quality of life (AQLQ) measures, were completed prior to and at the end of each treatment arm. Indoor concentrations of traffic particles were significantly reduced with the HEPA treatment but not with the “dummy” treatment. In participants with poorly controlled asthma and lower quality of life at baseline, ACQ and AQLQ scores were significantly improved (1.3 to 0.9, p = 0.003 and 4.9 to 5.5, p = 0.02, respectively) following the HEPA treatment. In this study, HEPA filtration is associated with improved clinical outcomes and quality of life measures in children with uncontrolled asthma.
... Observational panel studies with personal monitoring reported an adverse effect of the exposure to particulate matter on the peak expiratory flow rate (PEFR) in asthmatic children [9]. A few previous intervention studies showed that air purifiers could reduce indoor PM2.5 levels in asthmatic children's homes or classrooms, with improvements in their nasal symptoms [10] or lung function [11], respectively, although outcomes were obtained from relatively small samples (n = 8 children per group) [10] and the target intervention area was the classroom rather than the home. ...
... Observational panel studies with personal monitoring reported an adverse effect of the exposure to particulate matter on the peak expiratory flow rate (PEFR) in asthmatic children [9]. A few previous intervention studies showed that air purifiers could reduce indoor PM2.5 levels in asthmatic children's homes or classrooms, with improvements in their nasal symptoms [10] or lung function [11], respectively, although outcomes were obtained from relatively small samples (n = 8 children per group) [10] and the target intervention area was the classroom rather than the home. ...
Article
Full-text available
Various studies have indicated that particulate matter <2.5 µm (PM2.5) could cause adverse health effects on pulmonary functions in susceptible groups, especially asthmatic children. Although the impact of ambient PM2.5 on children's lower respiratory health has been well-established, information regarding the associations between indoor PM2.5 levels and respiratory symptoms in asthmatic children is relatively limited. This randomized, crossover intervention study was conducted among 26 asthmatic children's homes located in Incheon metropolitan city, Korea. We aimed to evaluate the effects of indoor PM2.5 on children's peak expiratory flow rate (PEFR), with a daily intervention of air purifiers with filter on, compared with those groups with filter off. Children aged between 6-12 years diagnosed with asthma were enrolled and randomly allocated into two groups. During a crossover intervention period of seven weeks, we observed that, in the filter-on group, indoor PM2.5 levels significantly decreased by up to 43%. (p < 0.001). We also found that the daily or weekly unit (1 µg/m 3) increase in indoor PM2.5 levels could significantly decrease PEFR by 0.2% (95% confidence interval (CI) = 0.1 to 0.5) or PEFR by 1.2% (95% CI = 0.1 to 2.7) in asthmatic children, respectively. The use of in-home air filtration could be considered as an intervention strategy for indoor air quality control in asthmatic children's homes.
... Children, compared to adults, represent a vulnerable group susceptible to the harmful effects of air pollution because their respiratory system is not fully developed, and they have a higher ventilation rate. Five studies evaluated the relationship between PAP use and health effects in children in homes (Eggleston et al., 2005;Butz et al., 2011;Noonan et al., 2017;Park et al., 2017;James et al., 2019). All the studies were conducted in the USA of children with asthma or allergic diseases. ...
... Most of the studies found lower asthma or nasal symptoms in children using PAPs. Indoor PM 2.5 was significantly associated with exacerbation of asthma in children (Park et al., 2017). ...
Article
A systematic literature review was carried out to examine the impact of portable air purifiers (PAPs) on indoor air quality (PM 2.5) and health, focussing on adults and children in indoor environments (homes, schools and offices). Analysed studies all showed reductions in PM 2.5 of between 22.6 and 92.0% with the use of PAPs when compared to the control. Associations with health impacts found included those on blood pressure, respiratory parameters and pregnancy outcomes. Changes in clinical biochemical markers were also identified. However, evidence for such associations was limited and inconsistent. Health benefits from a reduction in PM 2.5 would be expected as the cumulative body of scientific evidence from various cohort studies shows positive impacts of long-term reduction in PM 2.5 concentrations. The current evidence demonstrates that using a PAP results in short-term reductions in PM 2.5 in the indoor environment, which has the potential to offer health benefits. Crown
... In einer Pilotstudie in Fresno, Kalifornien, der am stärksten mit Feinstaubpartikeln belasteten Stadt in den USA, protierten Kinder mit Asthma davon, wenn im Wohn-und Schlafzimmer Lu reiniger mit HEPA-Filtern liefen [17]. ...
Article
Auf dem Allergo-Update präsentieren deutsche Experten ihren Kollegen alle wirklich wichtigen Neuigkeiten des Vorjahres im Bereich Allergologie. In den Vorträgen standen unter anderem neueste Erkenntnisse zur Allergieprävention, zur Allergenbelastung in Innenräumen, zur spezifischen Immuntherapie und zu berufsbedingten Allergien im Mittelpunkt.
... 82 Thermal comfort, adequate ventilation to remove classroom-generated pollution, and the supply of filtered outdoor air are simple measures to improve air quality. 44 Home-based intervention with air filters, including HEPA purifiers, found a reduction in asthma morbidity, and it may have other beneficial effects in nasal symptoms in children with AR. 83,84 The long-term filtration of pollutants with an air conditioner filter was associated with cardiovascular health of adults and to decrease blood pressure. 57 Research gaps and opportunities for interventions to reduce effects of solid fuel smoke on public health are well identified. ...
Article
Full-text available
Indoor environments contribute significantly to total human exposure to air pollutants, as people spend most of their time indoors. Household air pollution (HAP) resulting from cooking with polluting ("dirty") fuels, which include coal, kerosene, and biomass (wood, charcoal, crop residues, and animal manure) is a global environmental health problem. Indoor pollutants are gases, particulates , toxins, and microorganisms among others, that can have an impact especially on the health of children and adults through a combination of different mechanisms on oxidative stress and gene activation, epigenetic, cellular, and immunological systems. Air pollution is a major risk factor and contributor to morbidity and mortality from major chronic diseases. Children are significantly affected by the impact of the environment due to biological immaturity, prenatal and postnatal lung development. Poor air quality has been related to an increased prevalence of clinical manifestations of allergic asthma and rhinitis. Health professionals should increase their role in managing the exposure of children and adults to air pollution with better methods of care, prevention, and collective action. Interventions to reduce household pollutants may promote health and can be achieved with education, community, and health professional involvement.
... Installing air purifiers would greatly help to reduce the average exposure to PM 2.5 . Similarly, exposure levels to various airborne allergens would be reduced (e.g., Park et al. 2017). ...
Article
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Airborne transmission of SARS-CoV-2 through virus-containing aerosol particles has been established as an important pathway for Covid-19 infection. Suitable measures to prevent such infections are imperative, especially in situations when a high number of persons convene in closed rooms. Here we tested the efficiency and practicability of operating four air purifiers equipped with HEPA filters in a high school classroom while regular classes were taking place. We monitored the aerosol number concentration for particles >3 nm at two locations in the room, the aerosol size distribution in the range from 10 nm to 10 µm, PM10 and CO2 concentration. For comparison, we performed similar measurements in a neighboring classroom without purifiers. In times when classes were conducted with windows and door closed, the aerosol concentration was reduced by more than 90% within less than 30 minutes when running the purifiers (air exchange rate 5.5 h ⁻ ¹). The reduction was homogeneous throughout the room and for all particle sizes. The measurements are supplemented by a calculation estimating the maximum concentration levels of virus-containing aerosol from a highly contagious person speaking in a closed room with and without air purifiers. Measurements and calculation demonstrate that air purifiers potentially represent a well-suited measure to reduce the risks of airborne transmission of SARS-CoV-2 substantially. Staying for two hours in a closed room with a highly infective person, we estimate that the inhaled dose is reduced by a factor of six when using air purifiers with a total air exchange rate of 5.7 h ⁻ ¹.
... It is indeed a matter of deep concern and not possible to shut down all such activities to mitigate air pollution drastically (Chan and Yao 2008;Huang et al. 2009;Ito and Zhang 2016). With the available technology at present, it is possible to improve the air quality inside an enclosed space with the help of air purifiers, electrostatic precipitators or any similar equipment (Byeon et al. 2006;Chai et al. 2009;Kim et al. 2010;Tartakovsky et al. 2013;Chen et al. 2015;Park et al. 2016). To fight against outdoor exposure of PM pollution, protective masks are in use. ...
Article
In this study, we have made attempts to present a brief review of commercially available different off-line particulate matter (PM) air samplers to highlight the need of user-centric design thinking approach for improving air sampler's collection/measurement accuracy, operation and handling. The limitations in the existing design of off-line PM samplers in terms of field usability have been explored. For getting more accurate scientific results, improvement in inertial impactor is desired to resolve the problem of particle bounce-off. Execution of air sampling in remote/challenging sites with conventional air samplers is identified to be inexpedient. Redesigning of the conventional models with user-centric design perspective is also necessary to endorse user-ease in field air sampling. Design thinking is nowadays used as a creative problem-solving tool by many successful organizations. However, the intervention of user-centric design research is not much prominent in designing scientific instruments. Recent studies established that the number of ground-based air sampler that is in present use are inadequate and thus developing off-line field air samplers which are low in cost and integrated with different measurement techniques in a unified model is needed. This study welcomes user-centric design research as a must for designing future models of off-line air sampler and encourages collaboration of air scientists with the design research team.
... Cooper et al. (2021) concluded that the PAP could sufficiently maintain the indoor PM 2.5 level in a residential building, which can reduce around 45 % average after 90 min operated. However, most previous studies concentrated on exploring the PAP's performance when the occupants face special outdoor conditions (Brugge et al., 2017;Maestas et al., 2019;Spilak et al., 2014), such as wildfires, or when the occupants have a specific requirement for IAQ (Park et al., 2017;Weichenthal et al., 2013), such as asthma. Accordingly, there is little to explain how a commercial PAP could influence indoor particle concentration in a naturally ventilated office building under different outdoor conditions. ...
Article
Full-text available
This study conducted an experimental analysis of how indoor air quality (IAQ) is influenced by the outdoor air pollutants levels, infiltration rate, and occupants' behaviours. The impacts of these factors on IAQ were analyzed using on-site measurements and numerical simulations. The results contribute to a better understanding of how to control the Indoor Particulate Level (IPL) for the specific conditions of the studied building. Results showed that occupant behaviour was the primary factor in determining the IPL, significantly changing the number of outdoor particles introduced to the building. Moreover, it was found that the IPL was exponentially correlated to the Outdoor Particulate Level (OPL). Based on numerical simulations, this study concluded that smaller particles do not always have more chance than larger particles of accessing the indoor environment through the building envelope. Meanwhile, a steady-state indoor particle concentration numerical model was established and verified using the 4-fold cross-validation method. Finally, simulation results identified that the room infiltration rate had a positive linear impact on IAQ if the OPL was under 30 μg/m³. This is because the increased air exchange rate can help to dilute indoor air pollutants when the outdoor air is relatively clean.
... Our results also indicate that the key for mitigating personal exposure to PM 2.5 is to reduce PM 2.5 concentrations in indoor environments, which can be achieved by installing air purifiers or fresh air units in households and work places. A number of recent studies have demonstrated the effectiveness of using air purifiers in reducing indoor PM 2.5 concentrations, and the reported reduction rates for indoor PM 2.5 concentrations by regular household air purifiers vary between 30% and 40% (Cheng et al. 2016;Dai et al. 2019;Liu et al. 2018;Park et al. 2017). Significant reduction in PM levels by applying air purifiers have also been reported in public indoor environments, such as classrooms and gyms (Polidori et al. 2013;Pacitto et al. 2020). ...
Article
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Because of the severe air pollution in northern China, facemasks have gained popularity in this area in recent years. Although the results of previous studies have shown the effectiveness of wearing facemasks for intercepting particles, the individual differences and the overall health benefits of wearing facemasks have not been comprehensively documented. In this study, using both model and personal tests under various conditions, we test eight major brands of facemasks for their removal efficiencies (REs) of particulate matter (PM) in six size ranges (from 0.3 μm to >10 μm). The results are used to assess the overall exposure reduction at the individual and population levels in Beijing. We find significant differences in REs among PM sizes, facemask brands, pollution levels, and genders. Combining the information on the usage of various brands, facemask wearing rates, and PM2.5 concentrations in the ambient and indoor air in this area, we evaluate the overall effect of facemask wearing on PM2.5 exposure reduction. It is quantitatively demonstrated that because people spend most time indoors, facemask protection is limited. For facemask wearers, the overall exposure can be reduced by less than 20%, whereas the reduction rate is as low as 2.4 ± 1.6% for the entire adult populations even in the year with the highest level of pollution with an annual mean PM2.5 concentration of 102 ± 98 μg∙m−3. As a strategy of self-protection from long-term exposure to particulate matter, wearing facemasks outdoors is inferior to the installation of indoor air purifiers.
... Cardioprotective effects were reported in a randomized clinical trial and a double-blind randomized crossover trial (Morishita et al., 2018;Chen et al., 2015). Decreased asthmatic and allergic symptoms were observed in subjects after a HEPA-AP intervention (Park et al., 2017;Lanphear et al., 2011). However, no health benefits were observed after a filtration intervention in another two trials conducted in Beijing, Boston and Chelsea (Shao et al., 2017;Brugge et al., 2017). ...
Article
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Stand-alone portable air purifiers (APs) have become an increasingly popular method of controlling individual inhalation exposure. Exposure to bacterial endotoxins has a causative role in respiratory inhalation health. Here, we studied the changes in endotoxin levels in indoor air before and after purification by a portable AP equipped with HEPA (high-efficiency particulate air) filters. An increase in endotoxins was observed when a previously used AP was turned on to clean the air. Replacing the HEPA filters in the AP helped to mitigate the increase in endotoxins of larger sizes but not endotoxins of smaller sizes. Consequently, the use of APs could lead to increased endotoxin deposition in airways, especially in the alveolar region. The endotoxin concentrations on the HEPA filters were well correlated with the free DNA concentrations on the HEPA filters. This correlation indicates that the disrupted bacteria, which released free DNA, could also release endotoxins, thus making HEPA filters a source of indoor airborne endotoxins. Our results illustrate a potential endotoxin inhalation risk associated with HEPA-APs as an air cleaning strategy and highlight the importance of composition-specific air cleaning while reducing the particle number/mass.
... A decrease in indoor PM 2.5 levels by using air purifiers with high-efficiency particulate air (HEPA) filters can improve nasal symptoms in children with allergic rhinitis. 13 Some studies reported a positive association between the increased concentrations of indoor air pollutants and increased prevalence of asthma, rhinitis and upper respiratory tract infection in children. [14][15][16][17] Children exposed to higher air pollution levels are more vulnerable with increase in the severity of the disease. ...
Article
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Background. World Health Organization (WHO) has observed that around seven million people died every year globally due to indoor air pollution. The purpose of this study is to evaluate the effect of indoor air pollution on respiratory health [bronchial asthma (BA) and/or allergic rhinitis (AR)] in a paediatric population in the National Capital Region (NCR) of Delhi, India.
... In a pilot randomized controlled trial of 25 elementary school children with asthma in the Boston area, a HEPA filter intervention improved peak expiratory flow without affecting asthma symptoms or FEV 1 (70). Air filters may have beneficial effects outside the lung and have been shown to improve nasal symptoms in children with allergic rhinitis (71) and to decrease blood pressure values (66). Furthermore, air filtration systems have undergone several technological advances to improve the healthfulness of building ventilation in the time since some of these studies were performed (72). ...
Article
Air pollution is a grave risk to human health that affects nearly everyone in the world and nearly every organ in the body. Fortunately, it is largely a preventable risk. Reducing pollution at its source can have a rapid and substantial impact on health. Within a few weeks, respiratory and irritation symptoms, such as shortness of breath, cough, phlegm, and sore throat, disappear; school absenteeism, clinic visits, hospitalizations, premature births, cardiovascular illness and death, and all-cause mortality decrease significantly. The interventions are cost-effective. Reducing factors causing air pollution and climate change have strong cobenefits. Although regions with high air pollution have the greatest potential for health benefits, health improvements continue to be associated with pollution decreases even below international standards. The large response to and short time needed for benefits of these interventions emphasize the urgency of improving global air quality and the importance of increasing efforts to reduce pollution at local levels.
... In contrast to the earlier tranche of air purifier intervention studies, very few recent investigations have focused on respiratory outcomes. One exception demonstrated that the introduction of portable HEPA air purifiers into living rooms and bedrooms were effective in significantly reducing indoor PM 2.5 concentrations and nasal symptom scores in asthmatic children (Park et al., 2017). A trend towards an improvement in childhood asthma control test scores and mean evening peak flow rates was also reported. ...
Article
In today's ‘indoor generation’ most human activities take place within an enclosed space, characterised by a chemically diverse and complex air quality. Although source control is the universally preferred approach to reduce contaminants, this is becoming increasingly insufficient, technically unfeasible or economically unviable. The provision of adequate ventilation is also being challenged by invariably poor outdoor air quality and our quest for a low carbon economy. Whilst the former directly adds to the burden of indoor air pollution, both factors attract mitigation measures that are leading to efforts to seal off indoor spaces, which can increase exposure to endogenous indoor air pollutants, heighten health risks and curtail concentration, learning and productivity. Research to date on the role of air purification technologies in key indoor microenvironments demonstrates that air filtration produces clear reductions in indoor pollution concentrations. To confirm the optimistic modelled health/performance benefits associated with air purification further research is required, evaluating longer term interventions particularly in vulnerable populations, employing real-time sensors to quantitatively assess complete exposure profiles and optimizing technologies/strategies to remove specific indoor air pollutants (eg infiltrated versus endogenous particles, gases, chemically transformed organics) within the unique spaces where people live, learn, work and travel.
... According to the available studies, nasal application of mometasone or oral application of montelukast reduces the intensity of mild obstructive sleep apnea in children [65,66]. Another way of alleviating the symptoms of nasal obstruction may be the use of household air filters [67]. However, so far, no studies analyzing the direct impact of air filters on obstructive sleep apnea have been conducted. ...
Article
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Obstructive sleep apnea (OSA) is a growing social problem, particularly in well-developed countries. It has been demonstrated that obstructive sleep apnea is a significant risk factor for cardiovascular diseases, including arterial hypertension, ischemic heart disease, heart failure, rhythm/conduction disturbances, as well as cerebral stroke. The pathophysiology of these diseases is complex and multifactorial. We present the current state of research on behavioral and environmental factors that influence the relationship between OSA and cardiovascular changes. We discuss the relationship between obesity, alcohol, sedatives, environmental tobacco smoke, allergic diseases and environmental pollution on the one hand and OSA on the other. In this context, the environment should be considered as an important modulator of the relationship between OSA and cardiovascular diseases.
... 82 Thermal comfort, adequate ventilation to remove classroom-generated pollution, and the supply of filtered outdoor air are simple measures to improve air quality. 44 Home-based intervention with air filters, including HEPA purifiers, found a reduction in asthma morbidity, and it may have other beneficial effects in nasal symptoms in children with AR. 83,84 The long-term filtration of pollutants with an air conditioner filter was associated with cardiovascular health of adults and to decrease blood pressure. 57 Research gaps and opportunities for interventions to reduce effects of solid fuel smoke on public health are well identified. ...
... μg/m 3 , see Table 4), air purifiers that used HEPA filtration, and located in areas with outdoor PM levels and, occupancy and activity patterns that are similar to those observed in the UK (i.e., studies conducted in western Europe, and North America). Using this criteria, four studies in particular suggest that the efficiencies modelled were representative of the actual conditions expected in residences in the UK (Cheng et al., 2016;McNamara et al., 2017;Park et al., 2017;Ward et al., 2017). These studies had an average percent reduction of 53.5% ranging from 37 to 68%. ...
Article
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This work assessed the potential impact on mortality and life expectancy that would occur due to reductions of indoor PM2.5 in dwellings in the UK using portable air purifiers. Reductions in indoor PM2.5 concentrations from air purifier use were modelled using findings from the literature for mean air purifier efficiency, mean indoor PM2.5 concentrations associated with air purifier use, and the relative risks associated with exposure. Life-table models were used to estimate changes to mortality from the following PM2.5-associated diseases: lung cancer, lower respiratory infection (LRI), chronic obstructive pulmonary disease (COPD), ischemic heart disease (IHD), and stroke. Different scenarios were modelled to represent a range of daily use patterns, the starting age of use and the duration of the intervention. The overall impact of the central scenario, in which air purifiers were used during all hours whilst at home (15.6 h) for the entirety of the modelled period (birth to 97 years), was to increase life expectancy in the birth cohort by, on average, 138 and 120 days for males and females, respectively, and to add more than 23 million years of life (YLG) to the UK population. When used at home, air purifiers reduced indoor PM2.5 concentrations and prolonged life expectancy, but questions regarding feasibility of the intervention, occupant behaviour and social inequities remain. The estimation of the impact of use by the whole population is, however, important for informing policy and designing interventions.
... Cooper et al. (2021) concluded that the PAP could sufficiently maintain the indoor PM 2.5 level in a residential building, which can reduce around 45 % average after 90 min operated. However, most previous studies concentrated on exploring the PAP's performance when the occupants face special outdoor conditions (Brugge et al., 2017;Maestas et al., 2019;Spilak et al., 2014), such as wildfires, or when the occupants have a specific requirement for IAQ (Park et al., 2017;Weichenthal et al., 2013), such as asthma. Accordingly, there is little to explain how a commercial PAP could influence indoor particle concentration in a naturally ventilated office building under different outdoor conditions. ...
... Air purifiers are widely used to reduce indoor air pollution [23]. Most researchers believe that air purifiers are effective in reducing indoor PM2.5 and improving population health [36][37][38][39]. Dong et al. [40] found substantial respiratory benefits from ionized air purifiers. ...
Article
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Indoor air pollution is injurious to human health, even worse than outdoor air pollution. However, there is a lack of empirical evidence using large samples in developing countries regarding whether indoor air purification can improve human health by reducing indoor air pollutants. Using the data from the China Health and Nutrition Survey in 2015, this study analyzes the relationship between indoor air purification and residents’ self-rated health. We apply the generalized ordered logit model and find that indoor air purification has a significantly positive effect on residents’ self-rated health. This positive effect is limited to improving the probability of residents’ health level being rated “good”, and there is no significant movement between the two levels of “bad” and “fair”. The results also show that, as an important source of indoor air pollutants, solid fuels used in cooking significantly reduced residents’ self-rated health level. Additional results show the heterogeneity of the relationship between indoor air purification and resident health among groups with different characteristics. This study provides empirical evidence for further optimizing the indoor air environment.
... A decrease in indoor PM 2.5 levels by using air purifiers with high-efficiency particulate air (HEPA) filters can improve nasal symptoms in children with allergic rhinitis. 13 Some studies reported a positive association between the increased concentrations of indoor air pollutants and increased prevalence of asthma, rhinitis and upper respiratory tract infection in children. [14][15][16][17] Children exposed to higher air pollution levels are more vulnerable with increase in the severity of the disease. ...
... Two devices can be employed indoors to solve the problem of PM pollutants: air purifiers (APs) and fresh air units (FAUs) [7] [28][29][30][31][32], both of which are used separately in the rooms of SAC buildings. Although APs are equipped with fans and high efficiency particulate air filters (HEPA, whose filtration efficiency is over 99.97% for particles that have a diameter of 0.3 μm [33]) to circulate and purify indoor air, respectively, they cannot supply fresh air. ...
... Reductions in total PM 2.5 concentrations ranging from 20% to ∼70% have been observed in studies of residential HEPA or equivalent filters (26,42,43,64,70,86). However, air filtration is efficacious for lowering PM concentrations only insofar as sufficient contaminated air flows through the filter. ...
Article
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Unhealthy levels of air pollution are breathed by billions of people worldwide, and air pollution is the leading environmental cause of death and disability globally. Efforts to reduce air pollution at its many sources have had limited success, and in many areas of the world, poor air quality continues to worsen. Personal interventions to reduce exposure to air pollution include avoiding sources, staying indoors, filtering indoor air, using face masks, and limiting physical activity when and where air pollution levels are elevated. The effectiveness of these interventions varies widely with circumstances and conditions of use. Compared with upstream reduction or control of emissions, personal interventions place burdens and risk of adverse unintended consequences on individuals. We review evidence regarding the balance of benefits and potential harms of personal interventions for reducing exposure to outdoor air pollution, which merit careful consideration before making public health recommendations with regard to who should use personal interventions and where, when, and how they should be used. Expected final online publication date for the Annual Review of Public Health, Volume 43 is April 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
... According to a recent study in Fresno, CA, air purifiers are effective in reducing indoor PM2.5 and significantly improve symptoms and peak flow rates in children with allergic diseases. 5 However, the study was limited by the small number of study subjects and a very low basal PM2.5 levels in the city where the study was conducted. Also, recent evidence has indicated that microbial diversity and phthalate can exacerbate asthma. ...
Article
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Purpose: To evaluate the effects of air purifiers on the concentrations of indoor air pollutants and on asthma control in children. Materials and methods: In this randomized crossover trial, daily use of an air purifier filter was compared with a matched placebo with the filter off. Thirty elementary school students who had asthma were enrolled and randomly allocated to one of two groups. The primary endpoints were changes in indoor air quality, asthma severity, lung function, airway inflammatory, urine microbiome, and phthalate after the installation of air purifiers. PM2.5 and CO₂ were measured as indoor air pollutants. Asthma severity was assessed in terms of both symptom and medication scores acquired using a daily questionnaire. The higher the score, the better the symptom or the less frequent the use of medication. Peak expiratory flow rate and fractional exhaled nitric oxide were also measured. Results: The mean age of the enrolled patients was 9.2±1.98 years. The mean concentration of PM2.5 was 17.0 μg/m³ in the filter-off condition, but significantly lower at 9.26 μg/m³ in the filter-on condition. Medication scores were 6.9 for the filter-off and 7.12 for the filter-on conditions, reflecting a statistically significant decrease in the frequency of medications used during air purifier operation. Bacterial richness, as determined using the Chao 1 index, was markedly lower in the filter-on than the filter-off condition. Conclusion: This study suggests that air purifiers benefit medication burden in children with asthma by reducing PM2.5 levels.
... Researchers believe that fine particles have more impacts that are negative on human health than coarse particles. PM smaller than 2.5 mm can cause many pulmonary diseases to be hospitalized and have other adverse effects such as increased plaque in the arteries, heart attacks, other cardiovascular problems and premature death (E Oliveira et al., 2019;Park et al., 2017). These particulates can also be carried allergens that may be more effective on the respiratory system, possibly due to their ability to breaking through the respiratory tree (Luong et al., 2017;Tomczak et al., 2016). ...
Article
Purpose This paper aims to present the most influential factors on classroom indoor PM 2.5 (Particulate Matter < 2.5 µ), determining the level of PM 2.5 concentration in five pre-schools located in the most densely populated district of the Tehran metropolitan area (district 6) as a case study to consider the children's exposure to air pollutants and introducing a suitable model, for the first time, to predict PM 2.5 concentration changes, inside pre-schools. Design/methodology/approach Indoor and outdoor classes PM 2.5 concentrations were measured using two DUSTTRAK direct-reading instruments. Additional class status information was also recorded; concurrently, urban PM 2.5 concentrations and meteorological data were obtained from the fixed monitoring stations and Meteorological Organization. Then, the predicted concentrations of the indoor PM 2.5 , from introduced multiple linear regression model via SPSS, compared with the nearest urban air pollution monitoring stations data. Findings The average outdoor PM 2.5 concentration (43 ± 0.32 µg m ⁻³ ) was higher than the mean indoor (32 ± 0. 21 µg m ⁻³ ), and both were significantly ( p < 0.001) surpassing the 24-h EPA standard level. The indoor PM 2.5 concentrations had the highest level in the autumn (48.7 µg m ⁻³ ) and significantly correlated with the outdoor PM 2.5 ( r = 0.94, p < 0.001), the number of pupils, ambient temperature, wind speed, wind direction and open area of the doors and windows ( p < 0.001). These parameters, as the main determinants, have led to present a 7-variable regression model, with R ² = 0.705, which can predict PM 2.5 concentrations in the pre-school classes with more than 80% accuracy. It can be presumed that the penetration of outdoor PM 2.5 was the main source of indoor PM 2.5 concentrations. Research limitations/implications This study faced several limitations, such as accessibility to classrooms, and limitations in technicians' numbers, leading to researchers monitoring indoor and outdoor PM concentrations in schools once a week. Additionally, regarding logistical limitations to using monitoring instruments in pre-schools simultaneously, correction factors by running the instruments were applied to obtain comparable measurements. Originality/value The author hereby declares that this submission is his own work and to the best of its knowledge it contains no materials previously published or written by another person.
... The obtained trend can be attributed to the fact that larger particles (more inertia) are found in higher concentration in general indoor air (as a result of mechanical (human) activities as walking, sweeping and vacuuming) as compared to smaller ones that travel in airstream direction to get through cross-hatching of fiber and are intercepted by fiber (Wallace, 2008). Shiue et al. (2011) had reported a similar reduction percentage in the mass concentration of PM 0.5 and PM 0.25 , whereas reduction percentage in the mass concentration of PM 2.5 resembles with results in studies by Scheepers et al. (2015), Cheng et al. (2016), and Park et al. (2017). After deployment of AP II in the same sampling conditions, no such similar trend in reduction percentage (in the mass concentration of PMs) was noticed in the case of API . ...
Article
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The present study deals with an evaluation of the air purifier’s effectiveness in reducing the concentration of different sized particulate matter (PM) and ions in the real-world indoor environment. Two types of air purifiers (API and APII) mainly equipped with High-Efficiency Particulate Air (HEPA) filters that differed in other specifications were employed in general indoor air and the presence of an external source (candles and incense). The Gravimetric sampling of PM was carried out by SKC Cascade Impactor and further samples were analyzed for determining ions’ concentration while real-time monitoring of different sized PM was done through Grimm Aerosol Spectrometer (1.109). The result showed that API reduced PM levels of different sizes ranged from 12-52% and 29-53% in general indoor air and presence of external source respectively. Concerning the APII, a higher decrease percent in PM level was explored in presence of an external source (52-68%) as compared to scenarios of general indoor air (37-64%). The concentrations of the ions were noticed to be decreased in all three size fractions but surprisingly some ions’ (not specific) concentrations increased on the operation of both types of air purifiers. Overall, the study recommends the use of air purifiers with mechanical filters (HEPA) instead of those which release ions for air purification.
... However, the microorganisms on the lter will multiply, die or decompose, so the method above cannot directly re ect the microbial aerosols. Some scholars [23][24][25][26][27] have con rmed that air puri ers can effectively reduce the concentration of allergens in indoor air, thereby improving the clinical manifestations of patients with allergic rhinitis, and signi cantly reducing the drug needs. Some scholars [28] have proved that the air puri er has the effect of reducing the total colony number of the culture medium through the method of air sampling and fungus culture in the medium, but it has not been tested for bacterial species, and the puri cation of each microorganism cannot be seen directly. ...
Preprint
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Background The SARS-CoV-2 can spread through droplets, aerosols, etc. In the case of a severe outbreak of the SARS-CoV-2, the use of new air purifiers in work and living places has a certain effect on reducing the spread of the SARS-CoV-2. There are abundant microbial aerosols in the indoor medical environment. The innovation of this experiment lies in the use of long-term, large-volume sampling methods under the multi-factor dynamic conditions of normal diagnosis and treatment in the bronchoscope room, and the use of two microbial detection methods at the same time to study the removal efficiency of the new air purifier on microbial aerosols ; The innovation of the new air purifier lies in outdoor fresh air and steady-state displacement flow technology. Methods In this experiment, the test group and the control group were set up. Gelatin filtration membrane and PTFE filtration membrane were used to sample the microbial aerosols in the bronchoscope room. Long time (39.5h) and large sampling volume (70590L) was used. A total of 16 days of pure working time sampling was carried out for a period of 1 month. The collected specimens were tested by two methods: next-generation sequencing (mNGS) and microbial culture identification. The researcher retrieved and recorded the microbiological test results of related patients, and compared them with the results of this experiment. Results The result of next-generation sequencing (mNGS): The total purification efficiency was 88.0%. Microbial culture counting and identification results: the total purification efficiency is 87.5%. The results are statistically significant. There is a certain correlation between the experimental results and the clinical microbiological test results of patients. Conclusions 1. The new type of air purifier has a good effect on the removal of microbial aerosols in the bronchoscope room; 2. A variety of microorganisms involved in the experiment can be transmitted through aerosols. Discussion The new air purifier has a total removal efficiency of more than 85% of microorganisms under the dynamic environment of the hospital's normal diagnosis and treatment, and the purification efficiency of a single microorganism ranges 50%-100%. Such removal efficiency may have a positive effect for the control of the SARS-CoV-2 epidemic.
Article
Lots of epidemiological and experimental studies have found that ambient fine particulate matter (PM2.5) exposure is associated with the development of cardiopulmonary diseases, obesity and diabetes. This study focused on the effects of cumulative PM2.5 exposure on pulmonary and systemic inflammation and insulin resistance. Thirty-two 6-week-old male Balb/c mice were randomly divided into four groups (FA, PM, WEEK and DAY groups) and were continuously or intermittently exposed to concentrated PM2.5 or filtered air (FA) for four weeks using Shanghai Meteorological and Environmental Animal Exposure System (“Shanghai-METAS”). The levels of IL-6 and TNF-α in serum, bronchoalveolar lavage fluid (BALF), lung tissues and white adipose tissue (WAT) were measured. Meanwhile, the expression of NF-κB and phosphor-NF-κB in lung tissue was detected by Western blot. Glucose tolerance and insulin resistance were also determined at the end of exposure. The results found that the mice in PM group displayed moderate inflammatory cell infiltration in lung, whereas the mice in WEEK and DAY groups displayed slight inflammatory cell infiltration in lung. Compared with the mice in FA group, the mRNA expressions of IL-6 and TNF-α in lung tissue and WAT significantly increased in the mice of PM group. Importantly, IL-6 and TNF-α mRNA expressions in PM group were higher than those in WEEK and DAY groups. The protein expression of phospho-NF-κB in lung tissue showed that PM group showed the activation of NF-κB, which was higher than that in the WEEK and DAY groups. Meanwhile, the mice in PM group showed more severe glucose tolerance and insulin resistance than that in the WEEK and DAY groups. The results suggested that the reduction of PM2.5 cumulative exposure may alleviate pulmonary and adipose inflammation, insulin resistance and glucose tolerance impairment. The results provided a clue that the interruption of ambient PM2.5 exposures by systems such as indoor air purification could be of benefit to people’s health.
Article
This study involved a seasonal exposure assessment in a hospital environment using several air quality indicators including carbon monoxide (CO), carbon dioxide (CO2), particulate matter (PM10 and PM2.5), and total volatile organic compounds (TVOCs). We examined the distribution of and variation in the indoor and outdoor pollutant concentrations in 12 working areas across three hospitals, with an emphasis on capturing seasonal variations. We assessed correlations between measured indoor and outdoor levels to quantify the importance of indoor sources on air quality relative to outdoor sources. Our results indicated that while indoor and outdoor CO levels were below air quality standards/guidelines, measured PM2.5 and PM10 concentrations at several locations exceeded the standards 2- to 3.5-fold. We generally recorded higher indoor PM levels during the warm season, particularly during regional desert storm events. The ingress of particles from the outdoor to indoor environment was evident with high correlations between indoor and outdoor PM2.5 (r between 0.83 and 0.92) and PM10 (r between 0.74 and 0.86) levels, particularly during the warm season. Indoor to outdoor (I/O) ratios of PM2.5 and PM10 were mostly < 1. In contrast, indoor levels of CO2 and TVOCs exceeded outdoor concentrations during both the warm and cold seasons with I/O ratios >1 across all sampling locations. Our paper concludes with implications of high PM exposure and a suggested management framework for limiting such exposure in hospitals.
Article
Aim: Common indoor pollutants, as fine particulate matter (PM2.5), can damage people's health and cause skin allergies. However, it remains unknown which common pollutants can lead to allergy, such as, in children atopic dermatitis, and what is the key molecule. This study aimed to investigate the thymic stromal lymphopoietin (TSLP) produced from keratinocytes after environmental pollutant stimulation. Methods: PAM212 cells were treated by several pollutants, including PM2.5, formaldehyde, m-xylene, and 1,2,4-trimethylbenzene, and tried to analyze their relationships. The mRNA expression level of TSLP was determined by qPCR. The protein level of TSLP was detected by ELISA analysis. Results: The mRNA expression of TSLP was significantly up-regulated when PAM212 cells were stimulated by PM2.5 at 25 μg/ml for 12 h. Meanwhile, the protein level of TSLP in culture supernatant was increased. However, TSLP protein production was not detected in culture supernatant treated with formaldehyde, m-xylene, and 1, 2, 4-trimethylbenzene. Conclusion: PM2.5 promotes the expression of TSLP and may aggravate allergic response using this pathway.
Article
Gas cooking is an important source of airborne particulate matter (PM) indoors. Exposure to cooking-derived PM can lead to adverse human health impacts on non-smokers, especially in poorly-ventilated residential homes. Most of the previous studies on gas cooking emissions mainly focused on fine particles (PM2.5) with little information on their size-fractionation. Moreover, studies dealing with mitigation of indoor human exposure to cooking-derived PM are currently sparse. Therefore, a systematic study was conducted to investigate the characteristics of PM2.5 and size-fractionated PM derived from five commonly used cooking methods, namely, steaming, boiling, stir-frying, pan-frying and deep-frying in a poorly-ventilated domestic kitchen under controlled experimental conditions. Additionally, an indoor portable air cleaner was employed as a mitigation device to capture cooking-derived PM and improve indoor air quality (IAQ). Results revealed that the oil-based deep-frying cooking released the highest airborne particles which were about 170 folds higher compared to the baseline levels for PM2.5 mass concentrations. The use of the air cleaner showed a statistically significant (p < 0.05) reduction in the indoor PM2.5 levels. Moreover, PM<0.25 (particles with diameter ≤ 250 nm) showed a very high mass concentration (378.2 μg/m3) during deep-frying, raising human health concern. A substantial reduction (~60-85%) in PM<0.25 mass concentrations and their total respiratory deposition doses (RDD) in the human respiratory tract was observed while using the air cleaner during the five cooking methods. Furthermore, morphological characteristics and the relative abundance of trace elements in cooking-derived PM were also investigated. This study provides useful insights into the assessment and mitigation of indoor human exposure to cooking-derived PM.
Article
Filters can reduce indoor concentrations of particulate matter (PM2.5), but their benefits have not been well characterized. This study investigates exposure, health, and cost impacts of high efficiency filters in homes and schools, focusing on the asthma-related outcomes. Reductions in indoor exposures to PM2.5 from outdoor sources with enhanced filters (e.g., MERV 12) are estimated using probabilistic indoor air quality models, and avoided health impacts are quantified using health impact assessment. These methods are applied using data from Detroit, Michigan, an urban region with elevated asthma rates. Replacing inefficient filters with enhanced filters in schools would reduce the PM2.5-attributable asthma burden by 13% annually, with higher benefits for more efficient filters. Marginal costs average $63 per classroom or $32 per child with asthma per year. In homes, using efficient furnace filters or air cleaners yields 11 to 16% reductions in the asthma burden with an annualized marginal costs of $151 – 494 per household. Additional benefits include reductions in health risk for adults and lower exposures to other contaminants such as PM from indoor sources. Based on the included health outcomes, efficient filters in schools in particular is a potentially cost-efficient way to reduce the asthma-related health burden for children.
Article
Biomass fuel smoke, secondhand smoke, and oxides of nitrogen are common causes of household air pollution (HAP). Almost 2.4 billion people worldwide use solid fuels for cooking and heating, mostly in low- and middle-income countries. Wood combustion for household heating is also common in many areas of high-income countries, and minorities are particularly vulnerable. HAP in low- and middle-income countries is associated with asthma, acute respiratory tract infections in adults and children, chronic obstructive pulmonary disease (COPD), lung cancer, tuberculosis, and respiratory mortality. Although wood smoke exposure levels in high-income countries are typically lower than in lower-income countries, it is similarly associated with accelerated lung function decline, higher prevalence of airflow obstruction and chronic bronchitis, and higher all-cause and respiratory cause-specific mortality. Household air cleaners with high-efficiency particle filters have mixed effects on asthma and COPD outcomes. Biomass fuel interventions in low-income countries include adding chimneys to cookstoves, improving biomass fuel combustion stoves, and switching fuel to liquid petroleum gas. Still, the impact on health outcomes is inconsistent. In high-income countries, strategies for reducing biomass fuel-related HAP are centered on community-level woodstove changeout programs, although the results are again inconsistent. In addition, initiatives to encourage home smoking bans have mixed success in households with children. Environmental solutions to reduce HAP have varying success in reducing pollutants and health problems. Improved understanding of indoor air quality factors and actions that prevent degradation or improve polluted indoor air may lead to enhanced environmental health policies, but health outcomes must be rigorously examined.
Article
Importance Fine particles (particulate matter 2.5 μm [PM2.5]), a ubiquitous air pollutant, can deposit in the small airways that play a vital role in asthma. It appears to be unknown whether the use of a PM2.5 filtration device can improve small airway physiology and respiratory inflammation in children with asthma. Objective To discover what pathophysiological changes in the small airways are associated with using a PM2.5-removing device in the bedrooms of children with asthma. Design, Setting, and Participants Children with mild or moderate asthma were enrolled in this double-blind, crossover study. The participants used a true filtration device and a sham filtration device in their bedrooms in a random order for 2 weeks each with a 2-week washout interval. The study was conducted in a suburb of Shanghai, China, during a low-ozone season. Exposures Ozone and PM2.5 were measured inside bedrooms and outside a window. Main Outcomes and Measures Impulse oscillometry, spirometry, and fractional exhaled nitric oxide were measured at the beginning and the end of each intervention. Peak expiratory flow was measured twice daily at home. Results Forty-three children (5-13 years old; 26 boys [60%]) participated. Outdoor 24-hour mean PM2.5 concentrations were moderately high, ranging from 28.6 to 69.8 μg/m³ (median, 53 μg/m³). During true filtration, bedroom PM2.5 concentrations were a mean (SD) of 63.4% (35.9%) lower than during sham filtration. Compared with sham filtration, true filtration was significantly associated with improved airway mechanics, reflected in a 24.4% (95% CI, 11.8%-37.1%) reduction in total airway resistance, a 43.5% (95% CI, 13.7%-73.3%) reduction in small airway resistance, a 22.2% (95% CI, 2.2%-42.2%) reduction in resonant frequency, and a 73.1% (95% CI, 0.3%-145.8%) increase in airway reactance. True filtration was also associated with significant improvements in fractional exhaled nitric oxide (a 27.6% [95% CI, 8.9%-42.4%] reduction) and peak expiratory flow (a 1.6% [95% CI, 0.8%-2.5%] increase). These improvements were significantly associated with bedroom PM2.5 reduction. Improvements in small airway function were nonsignificant (8.4% [95% CI, −1.4% to 18.3%]) in all participants but significant (13.2% [95% CI, 1.2%-25.1%]) in participants without eosinophilic airway inflammation at baseline. No improvements were observed for forced vital capacity, forced expiratory volume during the first second, and the ratio of these in all participants or subgroups. Conclusions and Relevance Per these results, indoor PM2.5 filtration can be a practical method to improve air flow in an asthmatic lung through improved airway mechanics and function as well as reduced inflammation. This warrants a clinical trial to confirm. Trial Registration ClinicalTrials.gov Identifier: NCT03282864
Article
In much of the world, people spend on average 65% of their time indoors at home. It is, therefore, important to understand the quality of air in homes, and how best to improve it. Negative health impacts associated with exposure to particulate matter are well documented, and account for significant morbidity and mortality worldwide. Technologies are rapidly being developed and adopted to mitigate indoor air pollution, and portable home air purifiers (HAPs) are one of the most effective technologies available to clean the surrounding air of harmful pollutants of both indoor and outdoor origin. The aims of the research presented here were to explore the impact of a commercially available air purifier used in actual bedrooms on indoor PM2.5 concentrations and perceived indoor air quality, as well as to understand and describe how portable air purifiers are used by occupants. Results from the present study showed that PM2.5 concentrations in bedrooms were reduced by a mean of 45% over 90 min with HAP use. Participants’ subjective assessment of the indoor air when the HAP was on was positive. However, the predominant motivation and indicator of HAP use was thermal comfort, and not perceived air quality. If used properly, portable air purifiers used at home could be effective at reducing exposure to PM2.5 indoors.
Article
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Object: To prepare a national guideline for Otorhinolaryngologist who treat allergic rhinitis patients. Methods: The study was conducted by three authors, namely the writing support team. The support team made the study plan, determined the writing instructions, chose the subgroups including the advisory committee, the advisors for authors and the authors. A workshop was organized at the very beginning to explain the details of the study to the team. Advisors took the chance to meet their coworkers in their subgroups and determined the main headings and subheadings of the guideline, together with the authors. After key words were determined by the authors, literature search was done in various databases. The authors keep in touch with the advisors and the advisors with the advisory committee and the support group at every stage of the study. National and International published articles as well as the abstracts of unpublished studies, imperatively presented in National Congresses, were included in this guideline. Only Guideline and meta-analyses published in last seven years (2013-2017) and randomized controlled studies published in last two years (2015-2017) were included. After all work was completed by the subgroups, support team brought all work together and edited the article. Results: A detailed guideline about all aspects of allergic rhinitis was created. Conclusion: The authors believe that this guideline will enable a compact and up-to-date information on allergic rhinitis to healthcare professionals. This guideline is the first in the field of Otolaryngology in Turkey. It should be updated at regular intervals.
Chapter
Object: To prepare a national guideline for Otorhinolaryngologist who treat allergic rhinitis patients Methods: The study was conducted by three authors, namely the writing support team. The support team made the study plan, determined the writing instructions, chose the subgroups including the advisory committee, the advisors for authors and the authors. A workshop was organized at the very beginning to explain the details of the study to the team. Advisors took the chance to meet their coworkers in their subgroups and determined the main headings and subheadings of the guideline, together with the authors. After key words were determined by the authors, literature search was done in various databases. The authors keep in touch with the advisors and the advisors with the advisory committee and the support group at every stage of the study. National and International published articles as well as the abstracts of unpublished studies, imperatively presented in National Congresses, were included in this guideline. Only Guideline and meta-analyses published in last seven years (2013-2017) and randomized controlled studies published in last two years (2015-2017) were included. After all work was completed by the subgroups, support team brought all work together and edited the article. Results: A detailed guideline about all aspects of allergic rhinitis was created. Conclusion: The authors believe that this guideline will enable a compact and up-to-date information on allergic rhinitis to healthcare professionals. This guideline is the first in the field of Otolaryngology in Turkey. It should be updated at regular intervals. Key words: Allergic rhinitis, guideline, rhinitis
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Exposure to indoor air particulate pollution increases respiratory and cardiovascular morbidity and mortality, especially in the elderly. To assess a short-term, indoor air filtration's potential benefit on circulatory and cardiopulmonary health among healthy older people, a randomized, double-blind crossover trial was conducted with 24 healthy residents of an aged-care center in Chongqing, China in 2020. Each room received a high-efficiency particulate air filter air purifier and a placebo air purifier for two days. Fifteen circulatory system biomarkers of inflammation, coagulation, and oxidative stress; lung function; blood pressure (BP); heart rate (HR) and fractional exhaled nitric oxide (FeNO) were measured end of each two days. Indoor air particulate pollution was monitored throughout the study period. Linear mixed-effect models were used to associate health outcome variables with indoor particles. This intervention study demonstrated that air filtration was associated with significantly decreased concentrations of inflammatory and coagulation biomarkers, but not of biomarkers of oxidative stress and lung function. Just 48 h of air filtration can improve the cardiopulmonary health of the elderly. Air purifiers may be a public health measure that can be taken to improve circulatory and cardiopulmonary health among older people.
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Improving air quality in indoor environments where people live is of importance to protect human health. In this systematic review, we assessed the effectiveness of personal‐level use of air filtration units in reducing indoor particulate matters (PM) concentrations under real‐world situations following systematic review guidelines. A total of 54 articles were included in the review, in which 20 randomized controlled/crossover trials that reported the changes in indoor fine PM (PM2.5) concentrations were quantitatively assessed in meta‐analysis. Standardized mean differences (SMDs) were calculated for changes in indoor PM concentrations following air filtration interventions. Moderate‐to‐large reductions of 11%–82% in indoor PM2.5 concentrations were observed with SMD of −1.19 (95% CI: −1.50, −0.88). The reductions in indoor PM concentrations varied by geographical locations, filtration technology employed, indoor environmental characteristics, and air pollution sources. Most studies were graded with low‐to‐moderate risk of bias; however, the overall certainty of evidence for indoor PM concentration reductions was graded at very low level. Considering the effectiveness of indoor air filtration under practical uses, socio‐economic disparities across study populations, and costs of air filter replacement over time, our results highlight the importance of reducing air pollution exposure at the sources.
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Given the growing interest in community air quality monitoring using low-cost sensors, 30 PurpleAir II sensors (12 outdoor and 18 indoor) were deployed in partnership with community members living adjacent to a major interstate freeway from December 2017- June 2019. Established quality assurance/quality control techniques for data processing were used and sensor data quality was evaluated by calculating data completeness and summarizing PM2.5 measurements. To evaluate outdoor sensor performance, correlation coefficients (r) and coefficients of divergence (CoD) were used to assess temporal and spatial variability of PM2.5 between sensors. PM2.5 concentrations were also compared to traffic levels to assess the sensors’ ability to detect traffic pollution. To evaluate indoor sensors, indoor/outdoor (I/O) ratios during resident-reported activities were calculated and compared, and a linear mixed-effects regression model was developed to quantify the impacts of ambient air quality, microclimatic factors, and indoor human activities on indoor PM2.5. In general, indoor sensors performed more reliably than outdoor sensors (completeness: 73% versus 54%). All outdoor sensors were highly temporally correlated (r > 0.98) and spatially homogeneous (CoD<0.06). The observed I/O ratios were consistent with existing literature, and the mixed-effects model explains >85% of the variation in indoor PM2.5 levels, indicating that indoor sensors detected PM2.5 from various sources. Overall, this study finds that community-maintained sensors can effectively monitor PM2.5, with main data quality concerns resulting from outdoor sensor data incompleteness.
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In 2020, China for the first time developed guidelines for indoor fine particulate matter (PM2.5) in the draft document of indoor air standards, while the associated health implication remains unclear. Here, we first estimated the PM2.5 associated premature deaths was 965 thousand in 2019, with the indoor PM2.5 of outdoor origin accounting for 72.9%. Then, we examined the dynamic mortalities under a scenario matrix of 36 conditions, by incorporating various shared socioeconomic pathways in 2035, the draft guidelines and the contributions of ambient PM2.5 to indoor exposure. Although it may be improbable, the averages of premature deaths associated with ambient PM2.5 will be 1018–1361 thousand in 2035 when the worst-case scenario of guidelines mandating a yearly (rather than daily) indoor PM2.5 concentration of 75 µg/m³, compared to the averages of estimation were 816–1304 thousand for better-case scenario of 35 µg/m³. Under these scenarios, the increase in the number of premature deaths was mainly driven by population aging. In 2035, an ambitious target of yearly indoor PM2.5 concentrations of 15 µg/m³ is anticipated to reduce the number of deaths associated with ambient PM2.5 by approximately 25% of the 2019 baseline. Stricter guidelines to restrict the indoor PM2.5 concentrations are recommended to mitigate the mortality risk in the future.
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Compelling studies approve that fine particle matter (PM2.5) exposure was associated with high risk of respiratory disorders. However, the available data assessing the detailed influence of PM2.5 on lung was limited. To overcome the difficulty of inhalational PM2.5 exposure, the real-ambient PM2.5 exposure system was constructed. The mice were exposed to filtered air (FA) or real-ambient PM2.5 (PM2.5), and the adverse effect on lung was determined. Nuclear factor E2-related factor 2 (Nrf2) as a transcription factor, was reported to affect autophagy. Autophagy was proposed as a two-edge sword in respiratory disorders. Here, our data presented that PM2.5 exposure dramatically reduced the lung function of WT mice rather than Nrf2-/- mice. Consistently, thickened alveolar walls was observed in WT mice in PM2.5 exposure group, whereas the histological phenotype of Nrf2-/- mice exhibited no obvious alteration. Furthermore, PM2.5 exposure triggered low-grade production of inflammatory profile in WT and Nrf2-/- mice. Moreover, the protein levels of p62, Beclin1 and LC3B of WT mice rather than Nrf2-/- mice were also altered in PM2.5 exposure group. Taken together, the present study applied the real-ambient exposure system, revealed the adverse effect of air pollution on lung, and proposed the underlying mechanism.
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We measured real-time and integrated PM2.5 inside 8 occupied single-family homes in Fresno, California to evaluate how turbulent air mixing and pollutant removal caused by a filter-based air purifier influences the levels of fine particles in everyday indoor environments. In each home, we used a real-time monitor to log PM2.5 levels every 5 min over 12 weeks during which air purifiers were operating, except for a designed 3-day shutdown period for baseline measurements. We assessed how the operation of air purifiers changed the patterns of the frequency distributions for short-term (5-min) concentrations, which included spikes produced by sporadic indoor activities or emissions. This allowed us to examine the reduction effectiveness of air purifiers on concentrations of both recently-emitted and well-mixed background aerosols. We observed a systematic change in the 5-min PM2.5 distributions in different homes - while air purifiers reduced 96% of the 5-min concentrations, they increased the magnitudes of the top 4%, representing transient concentration peaks. This phenomenon is consistent with what would be theoretically expected based on passive scalar turbulence in fluid physics. We also collected gravimetric filter samples for PM2.5 composition, finding mean reductions of the long-term (2–5 day) concentrations of 29–37% for indoor PM2.5 and endotoxin. A less significant reduction (19–26%) was seen for Pb (Lead).
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The goal was to test the effects of high-efficiency, particulate-arresting (HEPA) air cleaners on unscheduled asthma visits and symptoms among children with asthma exposed to secondhand smoke. We enrolled 225 eligible children who were 6 to 12 years of age, had physician-diagnosed asthma, and were exposed to ≥5 cigarettes per day. We conducted a double-blind, randomized trial. Children were assigned randomly to receive 2 active or inactive HEPA air cleaners. Of 225 enrolled children, 110 (49%) were assigned to the intervention group and 115 (51%) to the control group; 215 (95%) completed the trial. During the trial, there were 42 fewer unscheduled asthma visits among children in the intervention group (18.5% [95% confidence interval: 1.25%-82.75%]; P = .043), compared with those in the control group, after adjustment for baseline differences. There was a significant difference in the reductions of levels of particles of >0.3 μm according to group assignment; there was a 25% reduction in particle levels in the intervention group, compared with a 5% reduction in the control group (P = .026). There were no significant differences in parent-reported asthma symptoms, exhaled nitric-oxide levels, air nicotine levels, or cotinine levels according to group assignment. These results hold promise for using HEPA air cleaners as part of a multifaceted strategy to reduce asthma morbidity, but further research is necessary before they can be recommended routinely for the medical management of asthma.
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Exposure and sensitization to pet allergens are associated with allergic asthma in children. Conflicting data have emerged regarding the potential benefit of air cleaners with respect to a reduction of indoor pet allergens and bronchial hyperresponsiveness (BHR). In a randomized controlled trial 36 asthmatic children with sensitization to cat and/or dog and significant exposure to cat and/or dog allergen (Fel d 1 and/or Can f 1 >500 ng/g of carpet dust) were included in order to study the effect of high-efficiency particulate arresting (HEPA) air cleaners placed in the living room and bedroom compared with the effect of sham air cleaners. Patients were allocated to two groups: group 1 exposed to active filters and group 2 exposed to sham filters. At month 0, after 6 months and after 12 months, pulmonary function testing and cold air challenge were performed, serum eosinophil cationic protein (ECP) and specific IgE to seven aeroallergens were determined, and carpet dust samples and filters were collected. Major pet allergen concentrations (Fel d 1, Can f 1) were determined in filters and bulk dust samples. Thirty patients completed the study. After 6 and 12 months, there was no significant change in delta FEV(1) after cold air challenge, or in the use of medication and serum ECP levels. However, there was a trend in the active group towards an improvement of bronchial hyperresponsiveness, whereas the sham filter group showed a deterioration of BHR. Although HEPA air cleaners retained airborne pet allergens, no effect on disease activity or allergen concentrations in bulk dust samples was observed in this study.
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Adverse human health effects have been observed to correlate with levels of outdoor particulate matter (PM), even though most human exposure to PM of outdoor origin occurs indoors. In this study, we apply a model and empirical data to explore the indoor PM levels of outdoor origin for two major building types: offices and residences. Typical ventilation rates for each building type are obtained from the literature. Published data are combined with theoretical analyses to develop representative particle penetration coefficients, deposition loss rates, and ventilation-system filter efficiencies for a broad particle size range (i.e., 0.001-10 microm). We apply archetypal outdoor number, surface area, and mass PM size distributions for both urban and rural airsheds. We also use data on mass-weighted size distributions for specific chemical constituents of PM: sulfate and elemental carbon. Predictions of the size-resolved indoor proportion of outdoor particles (IPOP) for various conditions and ambient particle distributions are then computed. The IPOP depends strongly on the ambient particle size distribution, building type and operational parameters, and PM metric. We conclude that an accurate determination of exposure to particles of ambient origin requires explicit consideration of how removal processes in buildings vary with particle size.
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It is important to focus on children with respect to air pollution because (1) their lungs are not completely developed, (2) they can have greater exposures than adults, and (3) those exposures can deliver higher doses of different composition that may remain in the lung for greater duration. The undeveloped lung is more vulnerable to assault and less able to fully repair itself when injury disrupts morphogenesis. Children spend more time outside, where concentrations of combustion-generated air pollution are generally higher. Children have higher baseline ventilation rates and are more physically active than adults, thus exposing their lungs to more air pollution. Nasal breathing in adults reduces some pollution concentrations, but children are more typically mouth-breathers--suggesting that the composition of the exposure mixture at the alveolar level may be different. Finally, higher ventilation rates and mouth-breathing may pull air pollutants deeper into children's lungs, thereby making clearance slower and more difficult. Children also have immature immune systems, which plays a significant role in asthma. The observed consequences of early life exposure to adverse levels of air pollutants include diminished lung function and increased susceptibility to acute respiratory illness and asthma. Exposure to diesel exhaust, in particular, is an area of concern for multiple endpoints, and deserves further research.
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Background: Asthma is one of the most common chronic diseases among school-aged children in the United States. Environmental respiratory irritants exacerbate asthma among children. Understanding the impact of a variety of known and biologically plausible environmental irritants and triggers among children in New Jersey - ozone, fine particulate matter (PM2.5), tree pollen, weed pollen, grass pollen and ragweed - would allow for informed public health interventions. Methods: Time-stratified case-crossover design was used to study the transient impact of ozone, PM2.5 and pollen on the acute onset of pediatric asthma. Daily emergency department visits were obtained for children aged 3-17 years with a primary diagnosis of asthma during the warm season (April through September), 2004-2007 (inclusive). Bi-directional control sampling was used to select two control periods for each case for a total of 65,562 inclusion days. Since the period of exposure prior to emergency department visit may be the most clinically relevant, lag exposures were investigated (same day (lag0), 1, 2, 3, 4, and 5 as well as 3-day and 5-day moving averages). Multivariable conditional logistic regression controlling for holiday, school-in-session indicator, and 3-day moving average for temperature and relative humidity was used to examine the associations. Odds ratios are based on interquartile range (IQR) increases or 10 unit increases when IQR ranges were narrow. Single-pollutant models as well as multipollutant models were examined. Stratification on gender, race, ethnicity and socioeconomic status was explored. Results: The associations with ozone and PM2.5 were strongest on the same day (lag0) of the emergency department visit (RR IQR=1.05, 95% CI 1.04-1.06) and (RR IQR=1.03, 95% CI 1.02-1.04), respectively, with a decreasing lag effect. Tree and weed pollen were associated with pediatric ED visits; the largest magnitudes of association was with the 5-day average (RR IQR=1.23, 95% CI 1.21-1.25) and (RR 10=1.13, 95% CI 1.12-1.14), respectively. Grass pollen was only minimally associated with the outcome while ragweed had a negative association. Conclusions: The ambient air pollutant ozone is associated with increases in pediatric emergency department asthma visits during the warm weather season. The different pollen types showed different associations with the outcome. High levels of tree pollen appear to be an important risk factor in asthma exacerbations.
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A substantial disparity in asthma prevalence and morbidity among urban children compared with their nonurban counterparts has been recognized for more than two decades. Because of the nature of urban neighborhoods, pest allergens, such as cockroach and mouse, are present in high concentrations in US urban housing and have both repeatedly been linked to asthma morbidity in sensitized children. In addition, there is a growing body of evidence demonstrating that concentrations of many pollutants are higher indoors than outdoors in both US and European urban communities and that exposures to indoor pollutants such as particulate matter (PM) and nitrogen dioxide (NO2 ) are independently associated with symptoms in children with asthma. Although environmental interventions are challenging to implement, when they reduce relevant indoor allergen and pollutant exposures, they are associated with clear improvements in asthma. Other modifiable risk factors in urban childhood asthma that have emerged include dietary and nutritional factors. Overweight and obese children, for example, may be more susceptible to the pulmonary effects of pollutant exposure. Insufficiency of vitamin D and folate has also emerged as modifiable risk factors for asthma morbidity in children. The identification of these modifiable risk factors for urban childhood asthma morbidity offers a ripe opportunity for intervention.
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Asthma can be exacerbated by environmental factors including airborne particulate matter (PM) and environmental tobacco smoke (ETS). We report on a study designed to characterize PM levels and the effectiveness of filters on pollutant exposures of children with asthma. 126 households with an asthmatic child in Detroit, Michigan, were recruited and randomized into control or treatment groups. Both groups received asthma education; the latter also received a free-standing high efficiency air filter placed in the child's bedroom. Information regarding the home, emission sources, and occupant activities was obtained using surveys administered to the child's caregiver and a household inspection. Over a one-week period, we measured PM, carbon dioxide (CO(2)), environmental tobacco smoke (ETS) tracers, and air exchange rates (AERs). Filters were installed at midweek. Before filter installation, PM concentrations averaged 28 µg m(-3), number concentrations averaged 70,777 and 1,471 L(-1) in 0.3-1.0 and 1-5 µm size ranges, respectively, and the median CO(2) concentration was 1,018 ppm. ETS tracers were detected in 23 of 38 homes where smoking was unrestricted and occupants included smokers and, when detected, PM concentrations were elevated by an average of 15 µg m(-3). Filter use reduced PM concentrations by an average of 69 to 80%. Simulation models representing location conditions show that filter air flow, room volume and AERs are the key parameters affecting PM removal, however, filters can achieve substantial removal in even "worst" case applications. While PM levels in homes with asthmatic children can be high, levels can be dramatically reduced using filters.
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Nighttime allergen exposures are a primary contributor to the development of allergic and asthmatic morbidities. Disease management guidelines recommend the use of environmental control measures to reduce these exposures, but clinically relevant reductions are difficult to achieve because most measures control only 1 allergen source among many in the bedroom environment. To determine whether a novel localized approach to nighttime allergen avoidance provides effective exposure reductions and clinical benefits. Thirty-five adults with perennial allergic rhinoconjunctivitis (dog, cat, or dust mite sensitivity) were randomized to receive PureZone, a combination therapy involving localized air filtration and pillow encasement, or placebo in a crossover trial with two 2-week treatment periods separated by a 1-week washout. Nasal and ocular allergy symptoms, quality of life, and breathing zone particulate exposure were assessed. Bedroom allergen dust samples were collected in the sleeping environment. Reductions (>99.99%) in allergen-sized particulate (> or = 0.3 microm) in the breathing zone led to significant improvements in nocturnal nasal and ocular allergy symptoms (P < .001) and quality of life (P = .02) for the active vs placebo device. Significant nocturnal symptom reductions vs placebo occurred the second night of use and were maintained for the duration of treatment; these reductions improved sleep problems in particular (P = .02). Allergens were detected in 100% of bedrooms, of which 44% had levels that exceeded sensitizing thresholds. The combination therapy of pillow encasement and localized air filtration provided effective nighttime allergen exposure reductions and clinical benefits without the use of adjunctive therapy.
Article
Ambient fine particles (particular matter <2.5 microm diameter [PM(2.5)]) and ozone exacerbate respiratory conditions including asthma. There is little documentation determining whether children are more vulnerable to the effects of ambient pollution than adults, or whether pollution causes life-threatening episodes requiring intensive care unit (ICU) admission. We investigate the relationship between severe asthma morbidity and PM(2.5) and ozone in the warm season, and determine whether there is an age-related susceptibility to pollution. Daily time-series analysis of 6008 asthma ICU admissions and 69,375 general (non-ICU) asthma admissions in 4 age groups (<6, 6-18, 19-49, and 50+ years) in 74 New York City hospitals for the months April to August from 1999 to 2006. The regression model adjusted for temporal trends, weather, and day of the week. Risks were estimated for interquartile range increases in the a priori exposure time window of the average of 0-day and 1-day lagged pollutants. Age was a significant effect modifier for hospitalizations, and children age 6 to 18 years consistently had the highest risk. Among children age 6 to 18 years, there was a 26% (95% CI, 10% to 44%) increased rate of ICU admissions and a 19% increased rate of general hospitalizations (95% CI, 12% to 27%) for each 12-microg/m(3) increase in PM(2.5). For each 22-ppb increase in ozone, there was a 19% (95% CI, 1% to 40%) increased risk for ICU admissions and a 20% (95% CI, 11% to 29%) increased risk for general hospitalizations. Warm weather patterns of ozone and PM(2.5) disproportionately affect children with asthma and appear responsible for severe attacks that could have been avoided.
Article
The allergist is generally recognized as possessing the greatest expertise in relating airborne contaminants to respiratory health, both atopic and nonatopic. Consequently, allergists are most often asked for their professional opinions regarding the appropriate use of air-cleaning equipment. This rostrum serves as a resource for the allergist and other health care professionals seeking a better understanding of air filtration.
Article
To evaluate the effect of a room high-efficiency particulate air (HEPA) cleaner on cat-induced asthma and rhinitis, 35 cat-allergic subjects who were living with one or more cats were studied in a double-blind, placebo controlled trial. After a 1 mo baseline period, subjects' bedrooms were equipped with an active or placebo air cleaner for the following 3 mo. Evaluations included monthly measurement of cat-allergen levels, daily morning, afternoon, and nighttime nasal- and chest-symptom scores, twice-daily measurement of peak-flow rates, daily medication scores, monthly spirometry, and methacholine (MCh) challenge testing before and after the study. Airborne allergen levels were reduced in the active-filter group as compared with the placebo group (p = 0.045). However, no differences were detected in settled-dust allergen levels (p = 0.485), morning, afternoon, or nighttime nasal-symptom scores (p = 0.769, 0.534, and 0.138), chest-symptom scores (p = 0.388, 0.179, and 0.215), sleep disturbance (p = 0.101), morning or afternoon peak-flow rates (p = 0. 424 and 0.679), or rescue medication use (nasal, p = 0.164, chest, p = 0.650), respectively. Although the combination of a HEPA room air cleaner, mattress and pillow covers, and cat exclusion from the bedroom did reduce airborne cat-allergen levels, no effect on disease activity was detected for any parameter studied.
Article
Exposure to cat and dog allergens is very common in the Western World and is a serious cause of asthma in sensitized subjects. We sought to study the clinical effects of air cleaners in living rooms and bedrooms of asthmatic children sensitized to cat or dog allergens. Twenty asthmatic children sensitized to pet allergens (cat/dog) and with an animal at home participated in a double-blind, placebo-controlled, cross-over study in which the effects of air cleaners placed in the living room and bedroom for 3 months were compared with the effects of sham air cleaners. Before and after each study period, lung function, airway hyperresponsiveness (adenosine monophosphate), and peak flow variation were recorded. Cat and dog allergen levels were assessed in the filters of the air cleaners. After a 3-month intervention with active air cleaners, airway hyperresponsiveness decreased significantly, showing a 1.2 doubling dose increase of PC(20 )adenosine (P =.003). Peak flow amplitude also decreased (P =. 045). Substantial amounts of airborne cat and dog allergen were captured by the air cleaners in living rooms and bedrooms as well. Allergen levels in floor dust were not changed. In young asthmatic patients sensitized and exposed to pets in the home, application of air cleaners in living rooms and bedrooms was accompanied by a significant improvement in airway hyperresponsiveness and a decrease in peak flow amplitude.
Article
The overall purpose of this study was to investigate how airborne house dust particles may contribute to an allergic immune response, and thereby also to asthma and other respiratory symptoms. The following aims were set: first, to quantify and characterize indoor suspended particulate matter (SPM) with regard to amount, as well as elemental and size distribution, second, to identify possible mechanisms by which SPM may affect the allergic immune response. A vast majority of the particles in SPM samples from homes in Oslo were found to be less than 2.5 microm in diameter. This PM(2.5) fraction contained, in addition to a large amount of sulfur aerosols and silicates, a lot of soot particles. Most of these were less than 1 microm in diameter. Using an immunogold labeling technique, we found that these soot particles carried cat, dog and birch allergens on their surface. These results show that indoor SPM contains a lot of potential allergen carriers, i.e. soot particles (carbon aggregates), most of them less that 1 microm in diameter and therefore able to transport allergens deep into the respiratory tree. We further found that diesel exhaust particles (DEP), which is likely the main soot component of SPM, adsorbed several well-known allergens in vitro. Furthermore, SPM was found to elicit a local lymph node inflammatory response, and to have an adjuvant activity on the production of IgE antibodies to ovalbumin (OA).
Article
Sensitization to aeroallergens has been found to be a dominant risk factor for asthma in population-based studies. Similar results in asthmatic children being managed in hospital-affiliated outpatient clinic have not been established. We therefore conducted a case-control study on asthmatic children attending a university hospital-based outpatient clinic to investigate the pattern of aeroallergen sensitization and to assess the correlation between asthma control and the presence of allergen-specific IgE-s. Asthmatic patients underwent a questionnaire assessment of their asthma control, skin prick tests (SPT) for allergen sensitization, and spirometric evaluation. Peripheral blood was collected from all subjects for in vitro serum specific IgE assay (RAST) to common aeroallergens. One hundred and seventy asthmatics (aged 9.8 +/- 3.7 years) and 57 age-matched control subjects were enrolled. Our patients had a median of two asthmatic attacks within 6 months prior to evaluation, and their median Disease Severity Score was 13. The median FEV1 in our asthmatic children was 98%, whereas serum logarithmic total IgE concentrations in patients and controls were 2.57 and 2.09, respectively (p < 0.0001). More than 85% of our asthmatic children were sensitized to house-dust mite (HDM), and sensitization to HDM and cat, as well as elevated serum total IgE concentration, was a significant risk factor for the development of asthma in this cohort. Several objective measures of asthma severity, as well as FEV1, correlated significantly with sensitization to HDM, pets, and cockroaches. In conclusion, indoor aeroallergens are one of the risk factors for the development and severity of mild-to-moderate asthma in Chinese children in Hong Kong.
Article
There are a variety of air cleaning devices that have been developed for the control of indoor allergens and irritants. These include both portable, room-sized units, and central units for use with a home's heating and ventilation system. While air cleaners can help to reduce some allergens, such as those produced by cats and dogs, they are unlikely to work for most other indoor allergens. The use of air cleaners for the management of allergic disease is reviewed in this article, and specific recommendations for their use are provided.
Article
Outdoor ambient air pollutant exposures in communities are relevant to the acute exacerbation and possibly the onset of asthma. However, the complexity of pollutant mixtures and etiologic heterogeneity of asthma has made it difficult to identify causal components in those mixtures. Occupational exposures associated with asthma may yield clues to causal components in ambient air pollution because such exposures are often identifiable as single-chemical agents (e.g., metal compounds). However, translating occupational to community exposure-response relationships is limited. Of the air toxics found to cause occupational asthma, only formaldehyde has been frequently investigated in epidemiologic studies of allergic respiratory responses to indoor air, where general consistency can be shown despite lower ambient exposures. The specific volatile organic compounds (VOCs) identified in association with occupational asthma are generally not the same as those in studies showing respiratory effects of VOC mixtures on nonoccupational adult and pediatric asthma. In addition, experimental evidence indicates that airborne polycyclic aromatic hydrocarbon (PAH) exposures linked to diesel exhaust particles (DEPs) have proinflammatory effects on airways, but there is insufficient supporting evidence from the occupational literature of effects of DEPs on asthma or lung function. In contrast, nonoccupational epidemiologic studies have frequently shown associations between allergic responses or asthma with exposures to ambient air pollutant mixtures with PAH components, including black smoke, high home or school traffic density (particularly truck traffic), and environmental tobacco smoke. Other particle-phase and gaseous co-pollutants are likely causal in these associations as well. Epidemiologic research on the relationship of both asthma onset and exacerbation to air pollution is needed to disentangle effects of air toxics from monitored criteria air pollutants such as particle mass. Community studies should focus on air toxics expected to have adverse respiratory effects based on biological mechanisms, particularly irritant and immunological pathways to asthma onset and exacerbation.
Article
Despite medical advice, many pet-allergic asthma sufferers refuse to remove the pet to which they are sensitized from their home. We aimed to assess the clinical effects of air cleaners in the homes of adult asthma patients sensitized and exposed to cats and/or dogs. We performed a randomized, parallel-group study of 30 asthmatic adults sensitized to and sharing a home with cats or dogs. The effects of placing air cleaners in the living room and bedroom for 12 months and using high efficiency particulate air filter vacuum cleaners (active group) were compared with using these vacuum cleaners alone (control group). Measures of airway responsiveness, treatment requirement, lung function, peak flow, reservoir and airborne allergen were recorded before, during and after the interventions. A beneficial clinical response was assessed in terms of a 'combined asthma outcome'. This was defined as a two or more doubling dose improvement in bronchial hyper-reactivity to histamine and/or a reduction in treatment requirement of at least one step change on the British Thoracic Society guidelines for asthma treatment. A beneficial clinical response was observed in 10/15 subjects in the active group compared with 3/15 in the control group after 12 months intervention (P = 0.01). No significant differences between the active and control groups were detected for changes in measures of lung function, reservoir pet allergen and airborne pet allergen during the study. Whilst the study design has not allowed complete exclusion of a placebo effect, we believe that this pragmatic study of adult asthmatic patients sensitized and exposed to pets resulted in a small, but significant improvement in combined asthma outcome.
Article
A growing body of research supports the role of outdoor air pollutants in acutely aggravating chronic diseases in children, and suggests that the pollutants may have a role in the development of these diseases. This article reviews the biologic basis of children's unique vulnerability to highly prevalent outdoor air pollutants, with a special focus on ozone, respirable particulate matter (PM 2.5 [<2.5 microm in diameter] and PM 10 [<10 microm in diameter]), lead, sulfur dioxide, carbon monoxide, and nitrogen oxides. We also summarize understanding regarding health effects and molecular mechanisms of action. Practitioners can significantly reduce morbidity in children and other vulnerable populations by advising families to minimize pollutant exposures to children with asthma, or at a broader level by educating policymakers about the need to act to reduce pollutant emissions. Management of children with asthma must expand beyond preventing exposures to agents that directly cause allergic reactions (and therefore can be diagnosed by means of skin tests) and must focus more attention on agents that cause a broad spectrum of nonspecific, generalized inflammation, such as air pollution.
Article
Abstract Abstract Comprehensive quantitative experiments were performed to assess the capabilities of several air-cleaning devices to create a particle-free microenvironment as a therapy for sleeping persons affected by allergic rhinitis and asthma. Six devices were evaluated, of which five were portable and intended to provide general air cleaning for bedroom-sized spaces. The sixth was intended for installation in front of the headboard of a bed and was designed to provide clean air focused in a space occupied by a sleeping person. The air-cleaning methods of the selected devices included high-efficiency particulate air (HEPA) filtering and electrostatic precipitation. Particle concentration measurements for six particle-size ranges and sound intensity measurements were made during 8-h, sleep-simulating periods. The effects of four parameters were studied: (i) device location, (ii) controlled air motion in the laboratory, (iii) airflow rate setting of the air-cleaning device, and (iv) controlled disturbances. To ensure a totally objective study, a special laboratory facility was constructed which enabled complete control of the experimental conditions. The measured concentration histories provided comprehensive evidence of the relative capabilities of the various devices for the specific air-cleaning function. It was found that the device designed to focus the cleaned air in the sleeping space fulfilled its goal and, in that regard, was clearly superior to all of the other air-cleaning devices.