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Abstract
Exposure to carbonyls (aldehydes and ketones) can produce adverse health effects. It is known that various sources of carbonyls are often present inside residences but little is known about their indoor source strengths. In the present paper, we used a database established in the relationships of indoor, outdoor, and personal air (RIOPA) study to estimate indoor source strengths of 10 carbonyls and outdoor contributions to measured indoor concentrations of these carbonyls. We applied a mass balance model to analyze paired indoor and outdoor carbonyl concentrations simultaneously measured in 234 RIOPA homes. Among all the measured carbonyls, formaldehyde, and acetaldehyde had the strongest indoor source strengths with the estimated median values of 3.9 and 2.6 mg h−1, respectively. Hexaldehyde also had large indoor source strengths with a median of 0.56 mg h−1. Acetone had the largest variations in indoor source strengths ranging from undetected to 14 mg h−1. The medians of the estimated indoor source strengths were 0.15 mg h−1 for propionaldehyde, 0.18 mg h−1 for glyoxal, 0.17 mg h−1 for methylglyoxal, and 0.23 mg h−1 for benzaldehyde. Acrolein and crotonaldehyde had the weakest indoor source strengths with no indoor sources detected in the majority of the RIOPA homes that were selected to have only nonsmoker residents. Consistent with the indoor source strength results, our estimated outdoor contributions to indoor concentrations were low for formaldehyde. In contrast, more than 90% of the indoor concentrations for acrolein and crotonaldehyde were from outdoor sources. The outdoor contributions to indoor concentrations for acetone, propionaldehyde, benzaldehyde, glyoxal, and methylglyoxal ranged from 10 to 90% across the RIOPA homes, suggesting that both indoor and outdoor sources had contributions to indoor concentrations of these compounds.
... Due to their highly important roles in the atmosphere, field studies on atmospheric carbonyls have been intensively conducted in a number of cities around the world. However, most of the studies are carried out in the cities of North and South America (Liu et al., 2006), Europe (Bakeas et al., 2003;Possanzini et al., 1996), and East and West Asia (Liu et al., 2022); there are few studies conducted in the cities of Southeast Asia. In Athens, Greece, Bakeas et al. (2003) found that formaldehyde, acetaldehyde, and acetone are the most three abundant among fifteen carbonyls, with the concentrations of formaldehyde, acetaldehyde, and acetone being 0. 05 -39, 4.32 -49, and 0.64 -198 µg m −3 (median: 15.9, 11.8, and 2.0 µg m −3 ), respectively. ...
... Variation in these carbonyl concentrations is heavily impacted by photochemical production, with the magnitude of photochemical production in summer (83 -93%) being stronger than in winter (33%). In the US cities, Liu et al. (2006) estimated the relationship between the indoor and outdoor concentrations of ten carbonyls and found that the outdoor levels of formaldehyde and acetaldehyde were strongly impacted by their indoor sources. Formaldehyde, acetaldehyde, and acetone are also the most abundant carbonyls with median concentrations of 9.95, 14.9, and 19.5 µg m −3 during the RIOPA study, respectively. ...
The aim of this study is to assess the spatiotemporal variation, sources, and health impacts of the carbonyl compounds (carbonyls) in Ho Chi Minh City (HCMC), the third-most populous city in Southeast Asia. Sampling was conducted according to the US.EPA Method TO-11A, from 2012 to 2016 in both the dry and the rainy seasons at twelve sites. The result shows that the carbonyl mixing ratios are high when compared to typical cities. Formaldehyde, acetaldehyde, and acetone are the most abundant carbonyls together accounting for 89% of the measured carbonyls. The carbonyl mixing ratio in rainy (46.0 ± 32.2 ppb) is about twofold higher than that in dry (23.7 ± 10.3 ppb). An inverse distance weighting method was adopted to map the spatial distribution of carbonyls across the city. The result shows that the carbonyl levels tended to be high in the city center. Three carbonyl sources are resolved by the PCA/APCS method: industrial sources and solvent usage (54%), vehicle exhausts (24%), cooking emissions (11%). Both lifetime cancer risk (LCR) and non-cancer hazard index (HIs) were calculated to estimate the health impacts on the community due to inhalation exposure to current carbonyl levels. The LCR values vary from 5.31 × 10⁻⁶ to 5.75 × 10⁻⁵ for formaldehyde higher than those of 6.61 × 10⁻⁷ to 1.36 × 10⁻⁵ for acetaldehyde, which mostly exceeded the US.EPA recommendation for five age groups. The hazard quotient values are 12.0 to 68.4 for acrolein, 0.44 to 2.84 for acetaldehyde, 0.55 to 1.85 for formaldehyde, and 0.13 to 0.89 for propionaldehyde.
... Due to their highly important roles in the atmosphere, field studies on atmospheric carbonyls have been intensively conducted in a number of cities around the world. However, most of the studies are carried out in the cities of North and South America (Liu et al., 2006), Europe (Bakeas et al., 2003;Possanzini et al., 1996), and East and West Asia (Liu et al., 2022); there are few studies conducted in the cities of Southeast Asia. In Athens, Greece, (Bakeas et al., 2003) found that formaldehyde, acetaldehyde and acetone were the most three abundant among fifteen carbonyls, with the concentrations of formaldehyde, acetaldehyde, and acetone being 0. 05 -39, 4.32 -49 and 0.64 -198 μg m -3 , (median: 15.9, 11.8 and 2.0 μg m -3 ) respectively. ...
... In the United States cities, (Liu et al., 2006) estimated the relationship between the indoor and outdoor concentrations of ten carbonyls, and found that the outdoor levels of formaldehyde and acetaldehyde were strongly impacted by their indoor sources. Formaldehyde, acetaldehyde and acetone were also the most abundant carbonyls with median concentrations of 9.95, 14.9 and 19.5 μg.m -3 during the RIOPA study, respectively. ...
The aim of this study is to assess the spatiotemporal variation, sources and health impacts of the carbonyl compounds (carbonyls) in Ho Chi Minh City (HCMC), the third-most populous city in Southeast Asia. Sampling was conducted according to the US.EPA Method TO-11A, from 2012 to 2016 in both the dry and the rainy seasons at twelve sites. The result shows that the carbonyl mixing ratios were high when compared to other cities. Formaldehyde, acetaldehyde and acetone were the most abundant carbonyls together accounting for 89% of the measured carbonyls. The carbonyl mixing ratio in rainy (46.0 ± 32.2 ppb) was about twofold higher than that in dry (23.7 ± 10.3 ppb). An inverse distance weighting method was adopted to map the spatial distribution of carbonyls across the city. The result shows that the carbonyl levels tended to be high in the city center. Three carbonyl sources were resolved by the PCA/APCS method: industrial sources and solvent usage (54%), vehicle exhausts (24%), cooking emissions (11%). Both lifetime cancer risk (LCR) and non-cancer hazard index (HIs) were calculated to estimate the health impacts on the community due to inhalation exposure to current carbonyl levels. The LCR values varied from 5.31×10 ⁻⁶ to 5.75×10 ⁻⁵ for formaldehyde higher than those of 6.61×10 ⁻⁷ to 1.36×10 ⁻⁵ for acetaldehyde, which mostly exceeded the US.EPA recommendation for five age groups. The hazard quotient values were 12.0 to 68.4 for acrolein, 0.44 to 2.84 for acetaldehyde, 0.55 to 1.85 for formaldehyde, and 0.13 to 0.89 for propionaldehyde.
... 8%). This distribution is different from other types of incense reported (Chuang et al. 2011;Lee and Wang 2004;Liu et al. 2006) or from cooking (Huang et al. 2011) in which FA is the most abundant. ...
... In researches related to indoor quality and carbonyl emission, Chuang, Lee, Liu, and Wang reported the concentration relation between emitted compound in that FA, AA, and Pro did not excess 3 times difference compared with each other (Chuang et al. 2011;Lee and Wang 2004;Liu et al. 2006;Wang et al. 2007). In this study, the level of AA from almost tested incense sample was found 1.5-90 times higher than FA level, while Pro was 3-26 times higher than FA. ...
Incense stick burning is one of casual household activity, especially in East and Southeast Asian countries, including Vietnam. In this study, nine incense stick types were collected from Vietnam and investigated the carbonyl emission profile. The result showed that in ten analyzed carbonyl compounds, propionaldehyde (3–84%, avg. 32%), acetaldehyde (8–90%, avg. 30%), and acetone (0–38%, avg. 9%) were the most abundant in terms of total weight emitted carbonyls, respectively. The fourth abundant aldehyde was HCHO (1–26%, avg. 8%). The concentration of formaldehyde (HCHO) in released smoke ranged from 46.65 ± 4.44 to 596.89 ± 279.17 μg/m3 (38.02 ± 3.62 to 486.46 ± 242.19 ppb). High concentration of these carbonyls can pose health risk. Therefore, the personal risk assessment of HCHO inhalation exposure was carried out by the burning simulation in a small unventilated room. The risk calculation showed that the cancer risk is 1.81 × 10−5, 24% higher than the base risk. However, the risk may be much higher.
... [2][3][4][5] Several oxygenated and polar VOCs are also known to be much higher indoors than outdoors. [6][7][8][9][10] In fact, recent measurements indicate that concentrations of total watersoluble organic gases (WSOGs) were 15 times higher, on average, inside 13 homes in New Jersey and North Carolina than directly outside, on a carbon basis (mg-C m À3 ). 11 While several polar VOCs are commonly targeted for measurement indoors such as aldehydes (e.g., formaldehyde, acetaldehyde), [8][9][10] and measurements of additional compounds are becoming more numerous, 7,12-14 polar, oxygenated and water-soluble organics are generally poorly characterized due to analytical challenges. ...
... [6][7][8][9][10] In fact, recent measurements indicate that concentrations of total watersoluble organic gases (WSOGs) were 15 times higher, on average, inside 13 homes in New Jersey and North Carolina than directly outside, on a carbon basis (mg-C m À3 ). 11 While several polar VOCs are commonly targeted for measurement indoors such as aldehydes (e.g., formaldehyde, acetaldehyde), [8][9][10] and measurements of additional compounds are becoming more numerous, 7,12-14 polar, oxygenated and water-soluble organics are generally poorly characterized due to analytical challenges. Compound classes that we expect to be in indoor air include: organic acids, nitrates, amines, phenols, peroxides, epoxides and glycols. ...
Characterization of residential indoor air is important to understanding exposures to airborne chemicals. While it is well known that non-polar VOCs are elevated indoors, polar VOCs remain poorly characterized. Recent measurements showed that total polar water-soluble organic gas (WSOG) concentrations are also much higher indoors than directly outdoors (on average 15× greater at 13 homes, on a carbon-mass basis). This work aims to chemically characterize these WSOG mixtures. Acetic, lactic, and formic acids account for 41% on average (30-54% across homes), of the total WSOG-carbon collected inside each home. Remaining WSOGs were characterized via high-resolution positive-mode electrospray ionization mass spectrometry. In total, 98 individual molecular formulas were detected. On average 67% contained the elements CHO, 11% CHN, 11% CHON, and 11% contained sulfur, phosphorus, or chlorine. Some molecular formulas are consistent with compounds having known indoor sources such as diethylene glycol (m/z+ 117.091, C4H10O3), hexamethylenetetramine (m/z+ 141.113, C6H12N4), and methacrylamide (m/z+ 86.060, C4H7NO). Exposure pathways, potential doses, and implications are discussed.
... Average FA concentrations in European offices were < 5 to 16 µg/m 3 (Mandin et al. 2017;Nørgaard et al. 2014), and in European public buildings, homes, and inhaled air (personal sampling), 17, 57, and 30 µg/m 3 , respectively (Geiss et al. 2011). Average concentrations in US public buildings were 12-25 µg/m 3 , e.g., Ceballos and Burr (2012) and Lukcso et al. (2016) and 20-40 µg/m 3 in Canadian and Californian homes (Gilbert et al. 2005(Gilbert et al. , 2008Liu et al. 2006). Substantially higher median concentrations of 153, 163 and 94 µg/m 3 , respectively, in newly renovated residences, schools, and offices, have been compiled in China over the past 30 years (Fang et al. 2022). ...
Formaldehyde (FA) is a ubiquitous indoor air pollutant emitted from construction, consumer, and combustion-related products, and ozone-initiated reactions with reactive organic volatiles. The derivation of an indoor air quality guideline for FA by World Health Organization in 2010 did not find convincing evidence for bronchoconstriction-related reactions as detrimental lung function. Causal relationship between FA and asthma has since been advocated in meta-analyses of selected observational studies. In this review, findings from controlled human and animal exposure studies of the airways, data of FA retention in the respiratory tract, and observational studies of reported asthma applied in meta-analyses are analyzed together for coherence of direct association between FA and asthma. New information from both human and animal exposure studies are evaluated together with existing literature and assessed across findings from observational studies and associated meta-analyses thereof. Retention of FA in the upper airways is > 90% in agreement with mice exposure studies that only extreme FA concentrations can surpass trachea, travel to the lower airways, and cause mild bronchoconstriction. However, taken together, detrimental lung function effects in controlled human exposure studies have not been observed, even at FA concentrations up 4 ppm (5 mg/m³), and in agreement with controlled mice exposure studies. Typical indoor FA concentrations in public buildings and homes are far below a threshold for sensory irritation in the upper airways, based on controlled human exposure studies, to induce sensory-irritative sensitization nor inflammatory epithelial damage in the airways. Analysis of the observational heterogeneous studies applied in the meta-analyses suffers from several concomitant multifactorial co-exposures, which invalidates a direct association with asthma, thus the outcome of meta-analyses. The evidence of a direct causal relationship between FA and asthma is insufficient from an experimental viewpoint that includes retention data in the upper airways and controlled animal and human exposure studies. Taken together, a coherence of controlled experimental findings with individual observational studies and associated meta-analyses, which suffer from caveats, is absent. Further, lack of identified evidence of FA-IgE sensitization in both experimental studies and observational studies agrees with indoor FA concentrations far below threshold for sensory irritation. The assessment of experimental data with uncontrolled observational studies in meta-analyses is incompatible with a direct causal relationship between FA and asthma or exacerbation thereof due to lack of coherence and plausibility.
... Research was performed on specific pollutants, such as hexaldehyde, acetaldehyde, and HCHO, at three urban locations in the US that used the relationships between the indoor, outdoor, and personal air (RIOPA). The research revealed that outdoor concentrations could affect indoor carbonyl concentrations (Liu et al. 2006). ...
No long-term solution can evaluate the social and environmental requirements of communities near industries, especially in developing countries. The global landscape of technology, innovation, and industry has undergone significant transformation since the start of the Industrial Revolution, which has significantly altered the traditional socioeconomic structure of society, especially in urban regions. In-dustrialization has had positive and negative effects on society and the environment, which has left an enduring impact that includes improved employment prospects and economic growth. However, it brings adverse impacts, such as more pollution, greenhouse gas emissions, health risks, and changes in local communities and lifestyles. Threfore, efficient instruments and remedies must be used to mitigate the adverse effects of industrial activity and advances. Livability and environmental impact evaluations have become crucial tools for transforming the social and ecological spheres. Creating air pollution concentration models, particularly for industrial plumes, is a research need that is unresolved by the current environmental impact assessment (EIA) guidelines and procedures. Industries present severe risks to the population and ecosystems, because of the rapid changes in their mechanisms. In addition, no standardized method exists for assessing communities close to urban industrial clusters that encircle industrial development regions in the EIA and social impact assessment (SIA) evaluations. The national building codes (NBCs), urban and regional development plans formulation and implementation (URDPFI), and model building bylaws ignore this discrepancy. Several organizations have developed substitute models, such as California puff (CALPUFF) model from the USEPA and California Department of Pollution Monitoring, which outline risk assessment techniques for different models. Cambridge Uni-versity's Atmospheric Dispersion Modeling System-Urban (ADMS), from Cambridge Environmental Research Consultants, stands out as a widely used tool for evaluating pollution dispersion. Given the complexity of industrial emissions from several sources within a cluster of firms, a new strategy to lessen the effects of industrial plumes on the populations that live close to these zones is desperately needed. This means that communities must be categorized geographically according to different building heights and unique building regulations, which consider factors such as wind direction, atmospheric conditions, and separation from the sources of the emissions. This study used a cross-sectional methodology for a literature review of different issues that are due to the industrial plume rise heights in different domains.
... Volatile organic compounds (VOCs) are emitted into the environment through various sources, including fossil fuel processing, industrial and agricultural operations, and automobile exhaust gases, which lead to serious health issues such as cancer, respiratory, liver and skin problems. [55][56][57] Up to date, a variety of technologies such as adsorption and catalytic degradation have been developed to eliminate VOCs. 58,59 Among the current available technologies, titania has been widely utilized to harvest solar light at ambient temperature for photocatalytic elimination of VOCs due to its high oxidation capacity, non-toxicity, low cost, and chemical stability. ...
In this work, a series of carbon-doped, amorphous titania were constructed by calcination of titania xerogel in argon for carbonization and subsequent calcination in air at 300 oC to deliberately...
... В городской атмосфере формальдегид (HCHO) является наиболее распространенным карбонильным соединением, которое признано повсеместно распространенным загрязнителем окружающей среды [1][2][3][4]. HCHO является известным канцерогенным соединением [5,6]. Он играет активную роль в фотохимии тропосферы, химии атмосферы и качества воздуха [7][8][9][10][11]. ...
Исследован характер изменения концентрации формальдегида в приземном слое атмосферы миллионного промышленного города центральной Сибири. Показано, что в 2009- 2010 году скачкообразно возросло содержание формальдегида в воздушной среде г. Красноярска. Характер годовой динамики концентрации формальдегида при этом не изменился. Однако, после 2010 года увеличилось среднемесячное содержание формальдегида в атмосфере.
... The most important of these limitations is the sample size restriction, Evidence indicates differences between indoor and outdoor air quality (Challoner & Gill, 2014;Chen & Zhao, 2011), and factors like indoor activities and ventilation conditions are the leading causes of these differences (Liu et al., 2006;Raunemaa et al., 1989). Although these factors may cause differences between indoor and outdoor air quality, several studies provide evidence of the interaction between indoor and outdoor air quality (Leung, 2015;Lonc & Plewa, 2011). ...
Background
Autism prevalence has increased considerably, but its etiology is still poorly understood. While there have been suggestions regarding associations between air pollution exposure and neurodevelopmental disorders, several studies have looked at the effect of air pollution exposure on autism. However, the results are inconsistent. The possible role of unknown confounders is mainly blamed for this inconsistency.
Methods
To minimize confounding effects, we evaluated the impact of air pollution exposure on autism using a family‐based case‐control study. Cases were individuals with a diagnosis of autism born between 2009 and 2012 in Isfahan city, Iran. The controls did not have a previous history of autism and were cousins of the case person. The controls were matched with the autistic cases in terms of residential location and age range. For each trimester of pregnancy, carbon monoxide (CO), nitrogen dioxide (NO2), ozone (O3), sulfur dioxide (SO2), and PM10 exposure were estimated using the inverse distance weighted method.
Results
The analysis indicates a significant association between CO exposure and autism in the second trimester (OR = 1.59; p = 0.046, 95% CI: 1.01–2.51) and entire pregnancy (OR = 2.02; p = 0.049, 95% CI: 1.01–2.95). Likewise, exposure to NO2 during the second trimester (OR = 1.17; p = 0.006, 95% CI: 1.04–1.31), third trimester (OR = 1.11; p = 0.046, 95% CI: 1.01–1.24), and entire pregnancy (OR = 1.27; p = 0.007, 95% CI: 1.07–1.51) were found to be associated with increased risk of autism.
Conclusions
Overall, our study found higher exposure to CO and NO2, particularly during the second and third trimesters of pregnancy, was significantly associated with a higher risk of autism.
... Biomass burning is an important source of CCs (Hellén et al., 2006;Kim et al., 2008;Liu et al., 2006;Schauer et al., 2001), compared with other sources (Possanzini et al., 2002;Possanzini et al., 1996;Pang and Lewis, 2011;Zhang et al., 2000). Zhu et al. (2021) found that biomass burning contributes approximately 27% to oxygenated volatile organic compounds (OVOCs), of which formaldehyde, acetaldehyde, and acetone account for approximately 60%. ...
Carbonyl compounds are important precursors of free radicals, ozone (O3), and secondary organic aerosols (SOA) in the atmosphere. Biomass burning is an important source of carbonyl compounds. To explore the formation pathway of carbonyl compounds from biomass burning and the effects of fuel composition and burning conditions, this study performed tube-furnace combustion experiments using three biomass types (rice straw, pine, and poplar) and their three component extracts (cellulose, hemicellulose, and lignin) at seven ignition temperatures (300–900 °C, 100 °C gradient) and two oxygen concentrations (21% and 10.5%). The results showed that the average emission factors of carbonyl compounds (EFCC) from rice straw, pine, and poplar were 2.28 ± 1.72, 3.09 ± 2.98, and 2.90 ± 2.78 g/kg, respectively. EFCC were significantly higher (5.37 ± 0.25 g/kg) in lower temperature (300–500 °C) stage than in higher temperature (0.55 ± 0.03 g/kg). Furthermore, oxygen reduction promoted the emission of carbonyl compounds, increasing the EFCC by 21.6% on average. The average EFCC for the three components of biomass decreased in the order of cellulose (3.78 ± 3.90 g/kg), hemicellulose (2.90 ± 2.60 g/kg) and lignin (1.98 ± 1.72 g/kg), and their CCs profiles were also different. Cellulose and hemicellulose produced more formaldehyde and acetaldehyde than lignin, contributing 71.1 ± 12.6%, 69.0 ± 4.4% and 62.4 ± 15.5% in CCs, respectively. Acetone was mainly produced by the combustion of hemicellulose and lignin. Aromatic aldehydes were mainly produced by lignin burning, and also were significantly affected by temperature, the proportion under higher temperature is 2.7 times that under lower temperature. The EFCC values by weighted average calculation from the three components were good matched with those of parent fuels (r = 0.98), while the fitting results for those species such as aromatic aldehydes were relatively weak (r = 0.66), showing that there are different formation pathways and sensitivity to fuel composition and burning condition among different CCs.
... In indoor environments, FM can be emitted directly from wood-based materials, construction materials, paintings, anthropogenic activities such as smoking, cooking, and cleaning, or by the oxidation of indoor VOCs, especially terpenes, with high yields (Salthammer, 2019). Indoor concentrations of FM can reach significantly higher levels than outdoors (Crump et al., 1997;Langer et al., 2015;Liu et al., 2006). Glyoxal (C 2 H 2 O 2 ; GL) is the lightest α-dicarbonyl compound. ...
Formaldehyde (FM) and glyoxal (GL) are important atmospheric species of indoor and outdoor environments. They are either directly emitted in the atmosphere, or they are formed through the oxidation of organic compounds by indoor and/or outdoor atmospheric oxidants. Despite their importance, the real-time monitoring of these compounds with soft ionization mass spectrometric techniques, e.g., proton transfer mass spectrometry (PTR-MS), remains problematic and is accompanied by low sensitivity. In this study, we evaluate the performance of a multi-ion selected ion flow tube mass spectrometer (SIFT-MS) to monitor in real-time atmospherically relevant concentrations of FM and GL under controlled experimental conditions. The SIFT-MS used is operated under standard conditions (SCs), as proposed by the supplier, and custom conditions (CCs) to achieve higher sensitivity. In the case of FM, SIFT-MS sensitivity is marginally impacted by relative humidity (RH), and the detection limits achieved are below 200 ppt (parts per trillion). Contrariwise, in the case of GL, a sharp decrease of instrument sensitivity is observed with increasing RH when the H3O+ ion is used. Nevertheless, the detection of GL, using NO+ precursor ion, is moderately impacted by moisture with an actual positive sensitivity response. Therefore, we recommend the use of the NO+ precursor for the reliable detection and quantitation of GL. This work evidences that SIFT-MS can be considered as an efficient tool to monitor the concentration of FM and GL in laboratory experiments, and potentially in indoor or outdoor environments, capable of identifying their primary emission or secondary formation through (photo)oxidation processes. Furthermore, SIFT-MS technology still allows great possibilities for sensitivity improvement and high potential for monitoring low proton transfer affinity compounds.
... A growing body of research has demonstrated that human exposure to a variety of airborne pollutants is often greater indoors than outdoors Ott and Roberts, 1998;Jones, 1999;Edwards et al., 2001;Weschler, 2006;Logue et al., 2011Logue et al., , 2012, particularly in residences where people spend most of their time (Klepeis et al., 2001). This is because there are many indoor and outdoor sources of airborne pollutants indoors that often lead to indoor pollutant concentrations that are higher than outdoors (Wallace et al., 1985;Sax et al., 2004;Liu et al., 2006;Meng et al., 2005;Adgate et al., 2004a,b). Volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), aldehydes (e.g., formaldehyde), and alcohols are emitted indoors from building materials (Wallace et al., 1987;Wolkoff, 1998;Salthammer et al., 2010), cleaning products (Nazaroff and Weschler, 2004;Singer et al., 2006), and personal care products (Steinemann et al., 2011). ...
Mechanical ventilation systems are used in residences to introduce ventilation air and dilute indoor-generated pollutants. A variety of ventilation system types can be used in home retrofits, influencing indoor air quality (IAQ) in different ways. Here we describe the Breathe Easy Project, a >2-year longitudinal, pseudo-randomized, crossover study designed to assess IAQ and adult asthma outcomes before and after installing residential mechanical ventilation systems in 40 existing homes in Chicago, IL. Each home received one of three types of ventilation systems in the study: continuous exhaust-only, intermittent powered central-fan-integrated-supply (CFIS), or continuous balanced system with an energy recovery ventilator (ERV). Homes with central heating and/or cooling systems also received MERV 10 filter replacements. Approximately weeklong field measurements were conducted at each home on a quarterly basis throughout the study to monitor environmental conditions, ventilation operation, and indoor and outdoor pollutants, including size-resolved particles (0.3–10 μm), ozone (O3), nitrogen dioxide (NO2), carbon dioxide (CO2), carbon monoxide (CO), and indoor formaldehyde (HCHO). Mean reductions in indoor/outdoor (I/O) ratios across all systems after the intervention were approximately 12% (p = 0.001), 10% (p = 0.008), 42% (p < 0.001), 39% (p = 0.002), and 33% (p = 0.007), for CO2, NO2, PM1, PM2.5, and PM10, respectively. There was a reduction in I/O ratios for all measured constituents with each type of system, on average, but with varying magnitude and levels of statistical significance. The magnitudes of mean differences in I/O pollutant concentrations ratios were generally largest for most pollutants in the homes that received continuous balanced with ERV and smallest in the homes that received intermittent CFIS systems, with apparent benefits to providing ventilation continuously rather than intermittently. All ventilation system types maintained similar indoor temperatures during pre- and post-intervention periods.
... Here, we compare data from the following, population-based studies: The Canadian national indoor air surveys 48,49 with several thousand participants, the French national dwellings campaign, 50,51 the U.S. RIOPA study, 52 and the Japanese national survey. 53 The comparison involves median values, because these were reported most frequently in statistical survey studies. ...
Indoor air concentrations of formaldehyde, furfural, benzaldehyde, and 11 aliphatic aldehydes (C2‐C11) were measured in residences of 639 participants in the German Environmental Survey for Children and Adolescents 2014–2017 (GerES V). Sampling was conducted using passive samplers over periods of approximately seven days for each participant. The most abundant compounds were formaldehyde and hexanal with median concentrations of 24.9 µg m−3 and 10.9 µg m−3, respectively. Formaldehyde concentrations exceeded the Guide Value I recommended by the German Committee on Indoor Guide Values (Ausschuss für Innenraumrichtwerte ‐ AIR) (0.10 mg m−3) for 0.3% of the participating residences. The sum of aliphatic n‐aldehydes between C4 (butanal) and C11 (undecanal) exceeded their Guide Value (0.10 mg m−3) for 2.0% of the residences. The geometric mean concentrations of most aldehydes were lower than in the earlier GerES IV (2003–2006) study. Formaldehyde and hexanal concentrations, however, were comparable in both studies and showed no significant difference. Indoor aldehyde concentrations did not exhibit significant correlations with factors collected in questionnaires, such as the age of the participants, their socio‐economic status, the location of the residence (former East/West Germany), migration background, tobacco exposure, and the type of furniture used. The validity of the passive sampler measurements was verified against active sampling techniques in a test chamber experiment.
... Outdoor air quality is seen as a poor indicator of human exposure to outdoor pollutants (Fan et al., 2015).The main reason for poor associations between outdoor concentrations and personal exposure concentrations can be explained by the time activity patterns of people, who spent the majority of the time in indoor places. Many studies (He, 2004;Liu et al., 2006) indicate that indoor air quality is strongly related to indoor emission activities such as combustion processes for heating or cooking, smoking or cleaning with chemicals products. In the majority of the health impact assessment of pollution in case no measured data are available for indoor environments, the concentration can be derived as a function of outdoor concentration, the effective penetration factor, and the contribution of indoor sources (Hänninen et al., 2017). ...
A health impact assessment of the indoor pollution was performed for various indoor sources: oven for heating, cooking, photocopy machine and smoke cigarettes. The mortality levels and hospital admissions associated with exposure to PM2.5 and NO2 concentrations have been calculated. We have modelled a two level house in Madrid city center where the office and the living floors are in the same building. The people follow a predefined activity patterns (time profiles) in the outdoor and indoor environments. In this experiment, we have performed a full year simulation using the EnergyPlus model to obtain the following parameters: building energy use, thermal behavior, airflow and indoor air quality simultaneously. Outdoor air quality and meteorological conditions were provided by the output of running the very well-known model WRF/Chem. The health impacts of the indoor emitting sources are higher in the warm months due to the operation of the air conditioning system. The largest impact on health is produced by the emissions that are released during cooking. The results also show a high correlation between indoor and outdoor concentrations when indoor emissions are not considered.
... In S2, the concentrations of all aldehydes were found to be statistically higher (p 2 < 0.001) than those measured during the reference week 2 showing that teaching activities related to manual work (painting, drawing, etc.) could contribute to aldehydes emissions inside the classroom. Indeed, it is unlikely that these aldehydes come from outside and enter the classroom during window openings during these 3 weeks as it was shown by Liu et al. (2006) in three urban areas of the United States where indoor concentrations were almost always higher for aldehydes such as acetaldehyde, benzaldehyde and hexanal (Liu Table 4 Summary of minimum; maximum and mean values of each aldehyde studied in School 2 namely Acetaldehyde (AA), Propionaldehyde (PA), Benzaldehyde (BA) and Hexanal (HA) during the whole campaign. C. Trocquet, et al. ...
This paper presents a field campaign conducted in two French elementary schools for 5 weeks aiming at identifying effects of occupation and ventilation practices on indoor aldehyde concentrations and discriminating aldehyde emission from building materials and furniture. The investigated classrooms were first empty and not occupied whereas the furniture was added the following week. Normal school activities were restarted for the last three weeks under various ventilation practices.
C2–C7 aldehydes concentrations were monitored with the conventional method based on DNPH derivatization using active sampling followed by off-line HPLC/UV analysis. Acetaldehyde (AA) and hexanal (HA) were the two main aldehydes present if formaldehyde is not considered. The weekly mean values of acetaldehyde concentrations were found in the range 9.5–13.1 μg m−3 (School 1), 9.4–17.6 μg m−3 (School 2) and equal to 5.3 μg m−3 (School 3). In Schools 2 and 3, weekly hexanal concentrations ranged between 3.3 and 5.4 μg m−3 but increased up to 40.1 μg m−3 in school 1 where painting work was performed during the week 2. Smaller amount of propionaldehyde (PA) and benzaldehyde (BA) were always detected, their weekly average concentrations being in the range 0.4–4.0 μg m−3 and 0.9–2.7 μg m−3 for PA and BA, respectively. The results supported by Student's tests show that building materials and furniture contribute to aldehyde emissions while ventilation significantly improves indoor air quality without being able to privilege one of the three ventilation scenarios tested.
... Previously, atmospheric dispersion modeling was used to estimate the household concentrations of indoor air pollutants in industrial areas [1,18,19]. Only a few studies actually measured individual exposure [20] and household concentrations [21][22][23], and these studies only focused on PM mass concentrations, elemental composition, and VOCs concentrations. However, other air pollutants e.g., CO, carbon dioxide (CO 2 ), NO 2 , SO 2 , and ozone (O 3 ) in households in industrial cities also need to be considered. ...
High concentrations of air pollutants and increased morbidity and mortality rates are found in industrial areas, especially for the susceptible group, children; however, most studies use atmospheric dispersion modeling to estimate household air pollutants. Therefore, the aim of this study was to assess the indoor air quality, e.g., CO, CO2, NO2, SO2, O3, particulate matter with aerodynamic diameter less than 2.5 μm (PM2.5), and their influence factors in children’s homes in an industrial city. Children in the “general school”, “traffic school”, and “industrial school” were randomly and proportionally selected. Air pollutants were sampled for 24 h in the living rooms and on the balcony of their houses and questionnaires of time–microenvironment–activity-diary were recorded. The indoor CO concentration of the traffic area was significantly higher than that of the industrial area and the general area. In regard to the effects of window opening, household NO2 and PM2.5 concentrations during window opening periods were significantly higher than of the reference periods. For the influence of cooking, indoor CO2, NO2, and PM2.5 levels during the cooking periods were significantly higher than that of the reference periods. The indoor air quality of children in industrial cities were affected by residential areas and household activities.
... Assuming the system is in a steady state, C, C ext , P, a, k, and Q are constant and Eq. 1 can be solved for C to give: Previous studies on the relationship between indoor/ outdoor HCHO concentrations (Lewis and Zweidinger 1992;Liu et al. 2006) showed that there is no significant losses when the outdoor compound penetrates the building envelop and enters into the room. In consequence, a value of P = 1 was considered in this study. ...
A measurement campaign was conducted in 24 student rooms where formaldehyde emissions from all the indoor surfaces were measured using a passive flux sampler (PFS) parallel to monitoring of indoor and outdoor concentrations as well as the assessment of air exchange rate. Two mass balance models were used to predict indoor concentrations basing on input data recorded during this measurement campaign. The first model only takes into account the total emission from the indoor sources and the incoming and outgoing flows of compound brought by the air exchange rate. The second model added to these terms a further component related to the overall rate of removal processes (or “indoor sinks”) which was assessed in these same rooms during a previous field test campaign. A good agreement was found between the concentrations calculated by the model with the component relative to indoor removal processes and the measured concentrations. On the other hand, the predicted concentrations with a first model tend to highly overestimate the measured concentrations by a factor 1.9 on average. Apportionment of formaldehyde inputs and losses in the rooms was estimated and discussed. The results highlighted that indoor removal processes are a component to consider for formaldehyde budget indoors.
... It is the most abundant carbonyl compound and recognized as ubiquitous environmental pollutant (Li et al., 2014;Parrish et al., 2012;Lei et al., 2009;Seco et al., 2007). HCHO is a known carcinogenic compound Liu et al., 2006a;IARC, 2004;Molina and Molina, 2002). It plays also an active role in the tropospheric photochemistry, atmospheric chemistry and air quality (Liu et al., 2006b;Possanzini et al., 2002;Viskari et al., 2000; Effect of Seasonal Variation on the Levels and Behaviours of Formaldehyde in the Atmosphere of a Suburban Area in Cairo, Egypt Salwa K. Hassan 1), * , Ahmeh A. El-Abssawy 1) , Mamdouh I. Khoder 1),2) Müller, 1997;Anderson et al., 1996). ...
Formaldehyde (HCHO) is a carcinogenic pollutant, has an active role in tropospheric photochemistry, and can be affected by seasonal variations. To our knowledge, this is the first comprehensive study of the effect of seasonal variation on the levels and behaviours of HCHO in the atmosphere of a suburban area (15 May City) in Cairo. Daytime and nighttime measurements of HCHO were performed from March 2014 to February 2015. The highest average daily concentrations of HCHO were found in summer and the lowest in winter. The difference was statistically significant (p≤0.001). Daily average HCHO concentrations in spring, summer, autumn and winter were higher than the corresponding values in many polluted cities in the world. This was true for both weekdays and weekends. HCHO was higher in daytime than nighttime on weekdays and weekends, and the differences in mean concentrations were statistically significant (p ≤0.001), except during the autumn and winter on weekends. Therefore, the contribution of photochemical reactions in the observed levels of HCHO might be greater than that of traffic emissions. This was further proved by the significant positive correlation found between daytime HCHO concentrations and temperature. HCHO concentrations were higher on weekdays than weekends, the differences in mean concentrations were statistically significant (p≤0.001). This may be attributed to higher emission of HCHO from higher traffic intensity during daytime. Significant positive correlations (p≤0.001) were found between daytime and nighttime HCHO concentrations, both on weekdays and weekends suggesting that HCHO comes from the same sources.
... Theo kết quả thống kê của tổ chức US.EPA [26][27][28], khoảng thời gian sinh hoạt và làm việc trong nhà ở các thành phố của người dân Mỹ chiếm tới 85 % thời gian trong ngày. Tuy chưa có các khảo sát nghiên cứu ở Tp. ...
Indoor air pollution, especially for the air toxic compounds such as carbonyls, is the most common issue in large cities. Indoor and outdoor air samples were simultaneously collected at six homes to estimate the pollution levels of carbonyl compounds at some points in the residential area, Ho Chi Minh City. The gaseous carbonyls were measured in the period of August and September, 2011 corresponding to the rainy season. The results showed that formaldehyde, acetaldehyde and acetone were the most abundant carbonyls in both indoor and outdoor air, accounted 80 % of the interested compounds, followed by propionaldehyde and benzaldehyde. In the outdoor air, the mean concentrations of formaldehyde, acetaldehyde and acetone were 15.21±6.42, 13.77±7.63, 12.11±11.72 μg.m-3, respectively. Meanwhile, the indoor concentrations were 25.45±19.49, 26.21±13.03 and 22.12±18.08 μg.m-3 for formaldehyde, acetaldehyde and acetone, respectively. Formaldehyde/acetaldehyde and acetaldehyde/ propionaldehyde ratios were 2.23±1.41 and 6.09±5.00, respestively, indicating that main sources of outdoor carbonyls came from the anthropogenic source. The mean carbonyl concentrations of the present study compared with those of other countries showed that indoor carbonyls were similar to other studies, but outdoor carbonyls were much higher. In addition, most of the indoor/outdoor ratios were slightly higher than 1 and levels of benzaldehyde and tolualdehyde were a little high in the indoor air. These results indicated that the indoor carbonyls were strongly affected by the outdoor air infiltration.
... Formaldehyde in this work was similar to the prior reports, but acetaldehyde was even higher than that measured in New York 23 and California. 12 The level of acetone was near the highest level reported in the literature (measured in Guangzhou, China 21 ) and the level of 2-butanone was the highest among all the reported data. One likely reason is air pollution from the ever-expanding chemical industry in the city. ...
Aldehydes including formaldehyde, acetaldehyde, and acrolein are toxic organic components of air pollution that cause lung cancer and cardiovascular disease with chronic exposure. The commonly used method for determining the levels of carbonyl compounds based on the derivatizing agent 2,4-dinitrophenylhydrazine is of limited use for ketones and unsaturated aldehydes because of issues such as low capture efficiencies, unstable derivatives, and long sample collection times. This work details the analysis of carbonyls in ambient air by a microreactor approach. The microreactor is fabricated on a silicon wafer and has thousands of micropillars in a microfluidic channel for uniformly distributing the air flow through the channel. The surfaces of the micropillars are coated with a quaternary ammonium aminooxy reagent, 2-(aminooxy)ethyl-N,N,N-trimethylammonium iodide (ATM), for chemoselective capture of carbonyl compounds by means of oximation reactions. ATM–carbonyl adducts are eluted from the microreactor and directly analyzed by Fourier transform ion cyclotron resonance mass spectrometry and ultrahigh-performance liquid chromatography–mass spectrometry. More than 20 carbonyls were detected in ambient air samples. Acetone, 2-butanone, acetaldehyde, and formaldehyde were the most abundant carbonyls in ambient air of the studied urban areas.
... 2,3 Low molecular weight aldehydes present in the atmosphere are mainly result of the combustion processes. 4,5 Due to hydrophilic nature, carbonyl compounds are water-soluble and thus easily transferable to soils, plants, and food. Health issues related to the presence of carbonyl compounds are owing to their high reactivity. ...
... NO 2 and PM 2.5 are both regulated outdoors by the US EPA's National Ambient Air Quality Standards (NAAQS) and have both indoor and outdoor sources inside many homes. Two of these priority hazards, acetaldehyde and formaldehyde, are primarily emitted by indoor sources such as pressed-wood products and consumer products [57][58][59]. The cumulative chronic health impacts from inhalation of this wide array of indoor pollutants, excluding radon and secondhand smoke, have been estimated to result in between 400 and 1100 disability-adjusted life-years (DALYs) lost per 100,000 persons per year, representing an estimated 5-14% of the annual non-communicable, non-psychiatric disease burden in the U.S. [60]. ...
Americans spend most of their time inside residences where they are exposed to a number of pollutants of both indoor and outdoor origin. Residential buildings also account for ∼20% of the primary energy consumed in the U.S. To provide a tool for future investigations of interactions between energy use and indoor air quality (IAQ) in homes across the U.S. population, we developed a custom set of nationally representative building energy and IAQ mass balance models that predict annual energy use for space conditioning and indoor concentrations of a number of pollutants of both indoor and outdoor origin across the U.S. residential building stock. The residential energy and indoor air quality (REIAQ) model framework is built in Python and integrates between EnergyPlus and a dynamic mass balance model. REIAQ utilizes historical weather data to predict hourly energy consumption, air change rates, and HVAC system runtimes, which are coupled with historical outdoor pollutant concentration data and assumptions for indoor emission sources and other factors to predict hourly indoor pollutant concentrations. Modeled indoor pollutants include PM2.5, UFPs, O3, NO2, and several volatile organic compounds (VOCs) and aldehydes. The REIAQ model set successfully predicted annual space conditioning energy consumption for the U.S. residential building stock within ∼2% of historical data. Modeled indoor concentrations, infiltration factors for outdoor contaminants, and indoor/outdoor ratios of each pollutant all matched closely with observations from prior field studies. Population-weighted annual average indoor pollutant concentrations were also used to estimate the chronic health burden of residential indoor exposures.
... In US between 1999 and 2001, indoor and outdoor carbonyl concentrations were measured in 234 personal air (RIOPA) homes in three urban areas of the United States[33]. The indoor source strengths for different carbonyl concentrations are reported in this study. ...
This study consisted in the study of indoor air quality with INCA-Indoor model, and especially the development of a fast methodology to identify the most sensitive parameters influencing indoor air quality. The methodology is based on a sensitivity program INCA-Indoor-D, which was built to identify the most important parameters affecting pollutant concentrations. With measurement data from MERMAID (2014-2015), it is intended to continue to evaluate the INCA-Indoor model, which was used to analyze the indoor air quality of a low energy building. The first application of the sensitivity program INCA-Indoor-D is performed to develop a comprehensive sensitivity analysis of indoor [OH] with respect to diverse parameters. Sensitivity has been settled with a classification of the parameters. The results in this study provide useful information about roles of different processes controlling indoor air quality and the effects of different parameters on indoor pollutant concentrations.
Volatile organic compounds (VOCs) are released from many sources indoors, with ingress of outdoor air being an additional source of these species indoors. We report indoor VOC concentrations for 124...
Previous time-integrated (2 h to 4 h) measurements show that total gas-phase water-soluble organic carbon (WSOC g ) is 10 to 20 times higher inside homes compared to outside. However, concentration dynamics...
Carbonyl compounds are ubiquitous in outdoor and indoor air. Due to the high electronegativity of the oxygen atom, they are polar in nature and the C=O group opens possibilities for...
Urban air quality is a topic which remains high on the scientific and political agenda. Concentrations of most air pollutants are higher in urban areas than in the surrounding rural regions, and given the high population densities, it is within urban areas that the majority of the population receive their air pollutant exposure. Despite the continued implementation of abatement measures, concentrations of air pollutants within urban areas frequently exceed health-based guidelines and stricter measures to restrict emissions are required. This comprehensive volume, written by authoritative authors, deals with the basic science of urban air pollution in relation to the sources and concentrations, and the atmospheric chemical and physical processes which determine those concentrations and lead to the formation of secondary pollutants by chemical reactions in the atmosphere. The health effects of urban air pollution are described as is the policy response designed to mitigate the problems. Some of the highest air pollutant exposures occur within underground railway systems and this topic is considered explicitly in its own chapter. With comprehensive coverage from sources through atmospheric processes, to human exposure and effects on health and the policy response, this topical work will be of interest to scientists and policy makers within this field as well advanced students.
The aim of this work is to better understand the effects of air infiltration on indoor air pollution. A set of simulations has been performed by coupling a building energy demand model with a pollutant transport model in the same EnergyPlus tool. Outdoor pollution and meteorological data are simulated with the WRF/Chem regional air quality and meteorological model, which is an innovative aspect of this work, as the outdoor environment data are taken from monitoring stations far away from the simulated building. The simulations show the behaviour of indoor pollution and energy demand under different types of infiltration rates and how they can affect different areas of the building. There is a strong positive correlation between indoor and outdoor air quality. Infiltration and ventilation increase the annual average NO2 concentration by up to 5.85%. Natural ventilation saves up to 3.24% electricity, but increases heating gas demand by up to 2.28% and NO2 concentration by up to 2.39%.
Acetaldehyde is a very volatile carbonyl compound with a boiling point of 20.1 °C. The industrial importance of acetaldehyde is comparatively small and tends to decrease. Nevertheless, the substance is ubiquitous in the environment, because acetaldehyde occurs in many chemical and biological processes as an intermediate and byproduct. Acetaldehyde plays an important role in atmospheric chemistry, it is formed during combustion and from the oxidation of fats and oils. Acetaldehyde primarily occurs in the metabolism of plant and animal organisms. Due to the diverse chemical reactions, there are a large number of potential sources, which means that acetaldehyde is also important for the indoor environment. Building products are often rich in fatty acids, which slowly decompose under the formation of aldehydes. Sources from human activities include the preparation of food, burning of candles, wood, and ethanol, as well as the consumption of cigarettes and e-cigarettes. Many other products and devices can release acetaldehyde, the human respiratory gas must not be disregarded, and acetaldehyde is present in outdoor air. Several organizations and institutions regard acetaldehyde as a priority indoor pollutant. This is due to its acute and chronic effects, but also to its classification as a carcinogenic substance. There are sufficient data for acetaldehyde in the atmosphere, as the substance is easily accessible analytically using the DNPH method and is thus often recorded in measurements. Nevertheless, to date, there has been no scientific work that comprehensively characterizes and evaluates acetaldehyde indoors. From the point of view of the necessity of such a summary, an overview of the properties of acetaldehyde and the most important reaction mechanisms is given, followed by a discussion of potential sources and indoor air concentrations. Finally, a health-related assessment of the substance is provided on the basis of indoor guide values.
Volatile organic compounds (VOCs) are an important precursor of ozone (O3) and secondary organic aerosols (SOA), which play vital roles on affecting the climate and human health. A key type of the VOC is carbonyls, which have been shown to be a significant source of radicals that directly influenced the oxidative capacity and nitrogen reservoirs, production of O3 and SOA. Carbonyls are being directly emitted through different natural and anthropogenic sources, or formed via secondary oxidation processes, thereby the characteristics of carbonyls have been found to vary temporally and spatially. Here we review the essential features of degradation and secondary formation of carbonyls processes in the atmosphere, followed by the speciation of carbonyls, source apportionments and their abundances in different environments around the world. This review also focuses on the roles of carbonyls in O3 and SOA formation on the basis of different parameterization methods and model simulation. Finally, based on the above summarized scientific findings of carbonyls over the past two decades, the future perspectives of carbonyl studies are suggested.
Formaldehyde (FM) and glyoxal (GL) are important atmospheric species of indoor and outdoor environments. They are either directly emitted in the atmosphere or they are formed through the oxidation of organic compounds by indoor and/or outdoor atmospheric oxidants. Despite their importance, the real-time monitoring of these compounds with soft ionization mass spectrometric techniques, e.g. proton transfer mass spectrometry (PTR-MS), remains problematic and is accompanied by low sensitivity. In this study, we evaluate the performance of a multi-ion selected ion flow tube mass spectrometer (SIFT-MS) to monitor in real-time atmospherically relevant concentrations of FM and GL under controlled experimental conditions. The SIFT-MS used is operated under standard conditions (SC), as proposed by the supplier, and customized conditions (CC), to achieve higher sensitivity. In the case of FM, SIFT-MS sensitivity is marginally impacted by RH, and the detection limits achieved are below 200 ppt. Contrariwise, in the case of GL, a sharp decrease of instrument sensitivity is observed with increasing RH when the H3O+ ion is used. Nevertheless, the detection of GL using NO+ precursor ion is moderately impacted by moisture with an actual positive sensitivity response. Therefore, we recommend the use of NO+ precursor for reliable detection and quantitation of GL. This work evidences that SIFT-MS can be considered as an efficient tool to monitor the concentration of FM and GL using SIFT-MS in laboratory experiments and potentially in indoor or outdoor environments. Furthermore, SIFT-MS technology still allows great possibilities for sensitivity improvement and high potential for monitoring low proton transfer affinity compounds.
Acrolein (2-propenal) is a reactive substance undergoing multiple reaction pathways and an airborne pollutant with known corrosive, toxic and hazardous effects to the environment and to human health. So far, investigating the occurrence of acrolein in indoor air has been challenging due to analytical limitations. The classic DNPH-method has proven to be error-prone, even though it is still recommended in specific testing protocols. Thus, different approaches for an accurate determination of ambient acrolein have been introduced. In this work, an overview of already published data regarding emission sources and air concentrations is provided. In addition, a new method for the quantitative determination of acrolein in environmental test chambers and in indoor air is presented. Analysis is carried out using thermal desorption and coupled gas chromatography/mass spectrometry (TD-GC/MS) after sampling on the graphitized carbon black (GCB) Carbograph™ 5TD. All analytical steps have been carefully validated and compared with derivatization techniques (DNPH and DNSH) as well as online detection using PTR-QMS. The sampling time is short due to the low air collection volume of 4 L. Although derivatization is not applied, a detection limit of 0.1 μg m-3 can be achieved. By increasing the sampling volume to 6 L, the limit of detection can be lowered to 0.08 μg m-3. No breakthrough during sampling or analyte loss during storage of the acrolein laden sampling tubes was found. Therefore, the presented method is robust, easy-to-handle and also very suitable for routine analyses and surveys.
Mineral particles are ubiquitous in the atmosphere and exhibit an important effect on the photooxidation of volatile organic compounds (VOCs). However, the role of mineral particles in the photochemical oxidation mechanism of VOCs remains unclear. Hence, the photooxidation reactions of acrolein (ARL) with OH radical (OH) in the presence and absence of SiO2 were investigated by theoretical approach. The gas-phase reaction without SiO2 has two distinct pathways (H-abstraction and OH-addition pathways), and carbonyl-H-abstraction is the dominant pathway. In the presence of SiO2, the reaction mechanism is changed, i.e., the dominant pathway from carbonyl-H-abstraction to OH-addition to carbonyl C-atom. The energy barrier of OH-addition to carbonyl C-atom deceases 21.33 kcal/mol when SiO2 is added. Carbonyl H-atom of ARL is occupied by SiO2 via hydrogen bond, and carbonyl C-atom is activated by SiO2. Hence, the main product changes from H-abstraction product to OH-adduct in the presence of SiO2. The OH-adduct exhibits a thermodynamic feasibility to yield HO2 radical and carboxylic acid via the subsequent reactions with O2, with implications for O3 formation and surface acidity of mineral particles.
Air pollutants are perhaps the largest cause of diseases and death in the world today. Increasing urbanization and industrialization have caused an increase in number of diverse forms and types of new pollutants, which are difficult to detect and characterize due to their stench behaviour and complex sources of production. Such pollutants have been called emerging pollutants (EPs) and their list is ever increasing. Therefore, the understanding of the method of analysis and health implication of (EPs) in air is critical to providing a more robust understanding of exposure routes, regulations and mitigation. EPs in air discussed in this study are not in any way exhaustive but limited to emerging VOCs (including acrylonitrile, 1-3-butadiene, chloroform, dichloromethane, ethylene oxides, formaldehyde, toluene, trichloroethylene, 1,4-Dioxane) and metals (arsenic, manganese, and vanadium), ultrafine particles, micro-and nano-plastics, engineered nanoparticles, diesel/black carbon and bioaerosols. Occurrence, detection and health implications of these EPs in air are still unfolding due to limited monitoring studies, lack of standard methodology and regulations. To address this knowledge gap, authors conducted an in-depth review of available information. Their spatial distribution, analytical methods and health implications are discussed including the novel coronavirus (COVID-19) as a potential EP in air. The study concluded with highlights of gaps in knowledge and suggestions to key areas for future research. This information is of general interest to environmental scientists and of specific interest to both health and sanitation workers and policymakers at private, government and international organizations.
This paper reported concentration characteristics of thirteen kinds of gaseous carbonyl compounds (CCs) in urban houses with schoolchildren in two different climatic zones of China, estimated schoolchildren’s daily inhalation dose of formaldehyde and acetaldehyde, and then evaluated potential health risks for schoolchildren. Formaldehyde was the most abundant CCs in the houses, following by acetone and acetaldehyde. Mean concentrations of indoor formaldehyde, acetaldehyde and acetone in summer were 39.4 μg/m³, 16.1 μg/m³ and 26.7 μg/m³, which were higher than the concentrations of 21.4 μg/m³, 9.9 μg/m³ and 16.5 μg/m³ in winter. Compared to winter, more kinds of CCs were detected in summer. The significant positive correlations between different CCs indicated CCs were coexisting in indoor environments and released from the same sources. Due to a longer time spent in child’s bedrooms, children’s inhalation doses of formaldehyde and acetaldehyde in child’s bedrooms were much higher than those in living rooms. The impact of formaldehyde exposure in the houses on children’s health was greater than acetaldehyde exposure. The average risk quotients for formaldehyde exposure in winter and summer were 20.74 and 39.34, while 4.65 and 6.97 for formaldehyde exposure. These results supplemented the limited data concerning children’s exposure to CCs and associated health risk in the houses of China.
In the last decades there is more awareness on the impact on human health of pollutants emitted during cooking processes, both from commercial and from domestic activities. In this study, a new method exploiting solid‐phase microextraction and gas chromatography coupled to mass spectrometry (SPME‐GC‐MS) was developed to analyse the volatile organic compounds (VOCs) emitted during cooking. The air above the cooking plate was sampled using a polyethylene terephthalate olfactometric bag that allows to transport the sample to the instrument location and to perform the SPME extraction of the sampled air. The efficiency of different extraction systems and different extraction times (1h, 8h, 16h and 24h) was evaluated in order to obtain sufficient sensitivity. Thus, the proposed system, combining the use of olfactometric bags and SPME‐GC‐MS, was applied for the first time to study VOCs emitted during cooking allowing to perform the analysis, even on samples produced in sites far from the instrument location, in an easy way and with instrumentations available in most of laboratories. Then, the method was applied to assess the efficiency of odour filters used in common kitchen hoods, using deep frying of potatoes in sunflower oil as cooking model system. VOCs were analysed in the air before and after passage through the filter, calculating then percentages of dejection for the different classes of VOCs, that resulted to be in the range 31‐77%.
Heterogeneous photocatalysis has been widely applied in various fields, such as photovoltaic cell, solar water splitting, photocatalytic pollutant degradation, and so on. Therefore, the reaction mechanisms involved in these important photocatalytic processes, especially in TiO2 photocatalysis, have been extensively investigated by various surface science techniques in the past decade. In this review, we highlight the recent progress that provides fundamental insights into TiO2 photocatalysis through direct tracking the evolution of single molecule photochemistry on TiO2 single crystal surfaces using a combination of scanning tunneling microscopy (STM) and other surface science techniques. Insight into the structures of various TiO2 surfaces is discussed first, which provides a basic concept on TiO2. Afterward, the details of the single molecule photocatalysis of several important molecules (water, alcohols, and aldehydes) on the model TiO2 surfaces are presented, which are trying to probe bond cleavages and the roles of adsorption sties and adsorption states in TiO2 photocatalysis step-by-step. Last, challenges and opportunities in single molecule photocatalysis on TiO2 are discussed briefly.
Cooking is recognized as an important source of particulate pollution in indoor and outdoor environments. We conducted more than 100 individual experiments to characterize the particulate and non‐methane organic gas emissions from various cooking processes, their reaction rates and their secondary organic aerosol yields. We used this emission data to develop a box model, for simulating the cooking emission concentrations in a typical European home and the indoor gas‐phase reactions leading to secondary organic aerosol production. Our results suggest that about half of the indoor primary organic aerosol emission rates can be explained by cooking. Emission rates of larger and unsaturated aldehydes likely are dominated by cooking while the emission rates of terpenes are negligible. We found that cooking dominates the particulate and gas phase air pollution in non‐smoking European households exceeding 1000 μgm−3. While frying processes are the main driver of aldehyde emissions, terpenes are mostly emitted due to the use of condiments. The secondary aerosol production is negligible with around 2 μgm−3. Our results further show, that ambient cooking organic aerosol concentrations can only be explained by super‐polluters like restaurants. The model offers a comprehensive framework for identifying the main parameters controlling indoor gas and particle phase concentrations.
The Air Composition and Reactivity from Outdoor aNd Indoor Mixing (ACRONIM) field campaign was conducted to investigate the impacts of natural ventilation (i.e., window opening and closing) on indoor air quality. In this study, a Thermal desorption Aerosol Gas Chromatograph (TAG) obtained measurements of indoor particle‐ and gas‐phase semi‐ and intermediately volatile organic compounds both inside and outside a single‐family test home. Together with measurements from a suite of instruments, we use TAG data to evaluate changes in indoor particles and gases at three natural ventilation periods. Positive matrix factorization was performed on TAG and adsorbent tube data to explore five distinct chemical and physical processes occurring in the indoor environment. Outdoor‐to‐indoor transport is observed for sulfate, isoprene epoxydiols, polycyclic aromatic hydrocarbons, and heavy alkanes. Dilution of indoor species is observed for volatile, non‐reactive species including methylcyclohexane and decamethylcyclopentasiloxane. Window opening drives enhanced emissions of semi‐ and intermediately volatile species including TXIB, DEET, diethyl phthalate, and carvone from indoor surfaces. Formation via enhanced oxidation was observed for nonanal and 2‐decanone when outdoor oxidants entered the home. Finally, oxidative depletion of gas‐phase terpenes (e.g., limonene and α‐pinene) was anticipated but not observed due to limited measurement resolution and dynamically changing conditions. This article is protected by copyright. All rights reserved.
Water-soluble organic gas (WSOG) concentrations are elevated in homes. However, WSOG sources, sinks, and concentration dynamics are poorly understood. We observed substantial variations in 23 residential indoor WSOG concentrations measured in real time in a North Carolina, U.S. home over several days with a high-resolution time-of-flight chemical ionization mass spectrometer equipped with iodide reagent ion chemistry (I-HR-ToF-CIMS). Concentrations of acetic, formic, and lactic acids ranged from 30 – 130, 15 – 53, and 2.5 – 360 g m-3, respectively. Concentrations of several WSOGs, including acetic and formic acids, decreased considerably (~ 30-50%) when the air conditioner (AC) cycled on, suggesting that the AC system is an important sink for indoor WSOGs. In contrast to non-polar organic gases, indoor WSOG loss rate coefficients were substantial for compounds with high O:C ratios (e.g., 1.6 – 2.2 h-1 for compounds with O:C > 0.75 when the AC system was off). Loss rate coefficients in the AC system were more uncertain, but were estimated to be 1.5 hr-1. Elevated concentrations of lactic acid coincided with increased human occupancy and cooking. We report several WSOGs emitted from cooking and cleaning as well as transported in from outdoors. In addition to indoor air chemistry, these results have implications to exposure and human health.
The characteristics of indoor light (intensity, spectral, spatial distribution) originating from outdoors have been studied using experimental and modeling tools. They are influenced by many parameters such as building location, meteorological conditions and the type of window. They have a direct impact on indoor air quality through a change in chemical processes by varying the photolysis rates of indoor pollutants. Transmittances of different windows have been measured and exhibit different wavelength cutoffs, thus influencing the potential of different species to be photolysed. The spectral distribution of light entering indoors through the windows was measured under different conditions and was found to be weakly dependent on the time of day for indirect cloudy, direct sunshine, partly cloudy conditions contrary to the light intensity, in agreement with calculations of the transmittance as a function of the zenithal angle and the calculated outdoor spectral distribution. The same conclusion can be drawn concerning the position within the room. The impact of these light characteristics on the indoor chemistry has been studied using the INCA-Indoor model by considering the variation of the photolysis rates of key indoor species. Depending on the conditions, photolysis processes can lead to a significant production of radicals and secondary species. This article is protected by copyright. All rights reserved.
Photochemistry is a largely-unconsidered potential source of reactive species such as hydroxyl and peroxy radicals (OH and HO2, “HOx”) indoors. We present measured wavelength-resolved photon fluxes and distance dependences of indoor light sources including halogen, incandescent, and compact fluorescent lights (CFL) commonly used in residential buildings; fluorescent tubes common in industrial and commercial settings; and sunlight entering buildings through windows. We use these measurements to predict indoor HOx production rates from the photolysis of nitrous acid (HONO), hydrogen peroxide (H2O2), ozone (O3), formaldehyde (HCHO) and acetaldehyde (CH3CHO). Our results suggest that while most lamps can photolyze these molecules, only sunlight and fluorescent tubes will be important to room-averaged indoor HOx levels due to the strong distance dependence of the fluxes from compact bulbs. Under ambient conditions, we predict that sunlight and fluorescent lights will photolyze HONO to form OH at rates of 10⁶ – 10⁷ molec cm⁻³ s⁻¹, and that fluorescent lights will photolyze HCHO to form HO2 at rates of ~10⁶ molec cm⁻³ s⁻¹; rates could be two orders of magnitude higher under high precursor concentrations. Ozone and H2O2 will not be important photochemical OH sources under most conditions, and CH3CHO will generally increase HO2 production rates only slightly.
An INdoor air Detailed Chemical Model (INDCM) was developed to investigate the impact of ozone reactions with indoor surfaces (including occupants), on indoor air chemistry in simulated apartments subject to ambient air pollution. The results are consistent with experimental studies showing that approximately 80% of ozone indoors is lost through deposition to surfaces. The human body removes ozone most effectively from indoor air per square meter of surface, but the most significant surfaces for C6-C10 aldehyde formation are soft furniture and painted walls owing to their large internal surfaces. Mixing ratios of between 8-11 ppb of C6-C10 aldehydes are predicted to form in apartments in various locations in summer, the highest values are when ozone concentrations are enhanced outdoors. The most important aldehyde formed indoors is predicted to be nonanal (5-7 ppb), driven by oxidation-derived emissions from painted walls. In addition, ozone-derived emissions from human skin were estimated for a small bedroom at nighttime with concentrations of nonanal, decanal and 4-oxopentanal predicted to be 0.5, 0.7 and 0.7 ppb respectively. A detailed chemical analysis shows that ozone-derived surface aldehyde emissions from materials and people change chemical processing indoors, through enhanced formation of nitrated organic compounds and decreased levels of oxidants. This article is protected by copyright. All rights reserved.
Indoor air quality problems resulting from the emission of volatile organic compounds (VOCs) have become an issue of increasing concern. Emissions from building and furnishing materials, which are frequently constructed from particleboard and medium density fiberboard (MDF), are a potentially important contributor of indoor VOCs. In this research, VOC emissions from particleboard and MDF were measured in small (53-L) stainless steel chambers for 4 days. Samples were collected from 53 of the 61 U.S. mills that produce particleboard and MDF. Each mill identified the predominant tree species used to manufacture the panels. Laboratory tests were conducted at room temperature and 45 percent relative humidity. Gas chromatographic/mass spectrometric analysis was used to identify and quantify VOC compounds. The predominant compounds identified in the emissions from particleboard and MDF samples were terpenes and aldehydes, although small straight-chain alcohols and ketones were also found. This study describes the aldehyde emission data, excluding formaldehyde. Emissions of small straight-chain aldehydes, such as hexanal, pentanal, heptanal, octanal, and nonanal, generally exceeded emissions of other compounds and accounted for more than 50 percent of total VOC emissions. All 53 particleboard and 16 of 18 MDF samples emitted hexanal, the most prevalent aldehyde found (excluding formaldehyde). The tests showed differences in VOC composition and emission factors by product and tree type. On average, aldehyde emissions from southern pine MDF samples considerably exceeded the aldehyde emissions from southern pine particleboard. Emissions from all other MDF samples, however, were lower than those from particleboard samples in the same species group. With the exception of formaldehyde, aldehydes are not added to the adhesives used to bond wood, and they have not previously been reported as extractable compounds in wood. Degradation of the wood or its secondary metabolites is probably responsible for the presence of the aldehydes.
Aldehydes are air pollutants with the potential to act as strong sensory irritants. Outdoors, these compounds play a part in the complex system of photochemical atmospheric reactions, and they are directly released by traffic and other combustion sources. Indoors, numerous emission sources have been identified, for example tobacco smoking or furniture. The objective of the present study was to measure average concentrations of selected aldehydes in typical urban environments. A pilot study was carried out in Nancy, a medium-sized town in the Northeast of France. Outdoor concentrations of seven aldehydes were measured by exposing passive samplers for two periods each lasting five days. 30 samplers were installed at background sites and at sites where people spend more of their time. Moreover, 20 volunteers were equipped with personal samplers, which they carried on them during the first five days. Concentrations were also measured in their homes and offices. The results show that the highest outdoor concentrations are found in the centre of Nancy. However, aldehyde concentrations are much higher indoors than outdoors, even when compared with a period of meteorological conditions "favouring" higher aldehyde concentrations. Office and home concentrations agree with concentrations obtained with personal samplers. It is furthermore shown that the sum of formaldehyde and acetaldehyde concentrations may be used as a tracer for the group of aldehydes studied.
In the United States, 48 million adults smoke 3.5-5 x 10(11) cigarettes/year. Many cigarettes are smoked in private residences, causing regular environmental tobacco smoke (ETS) exposure to roughly 31 million nonsmokers (11% of the US population), including 16 million juveniles. (Upper bound estimates are 53 million exposed nonsmokers including 28 million juveniles.) ETS contains many chemical species whose industrial emissions are regulated by the US federal government as hazardous air pollutants (HAPs). In this paper, average daily residential exposures to and intakes of 16 HAPs in ETS are estimated for US nonsmokers who live with smokers. The evaluation is based on material-balance modeling; utilizes published data on smoking habits, demographics, and housing; and incorporates newly reported exposure-relevant emission factors. The ratio of estimated average exposure concentrations to reference concentrations is close to or greater than one for acrolein, acetaldehyde, 1,3-butadiene, and formaldehyde, indicating potential for concern regarding noncancer health effects from chronic exposures. In addition, lifetime cancer risks from residential ETS exposure are estimated to be substantial ( approximately 2-500 per million) for each of five known or probable human carcinogens: acetaldehyde, formaldehyde, benzene, acrylonitrile, and 1,3-butadiene. Cumulative population intakes from residential ETS are compared for six key compounds against ambient sources of exposure. ETS is found to be a dominant source of environmental inhalation intake for acrylonitrile and 1,3-butadiene. It is an important cause of intake for acetaldehyde, acrolein, and formaldehyde, and a significant contributor to intake for benzene.
Concentrations of polycyclic aromatic hydrocarbons (PAHs), PM2.5, and organic and elemental carbon (OC and EC) were measured in 48 h integrated samples collected in the indoor and outdoor air in Los Angeles, CA, Houston, TX, and Elizabeth, NJ from July 1999 to June 2000. The objective of the study was to evaluate the hypothesis that outdoor air pollution contributed strongly to indoor air pollution. The measured partition coefficients of PAHs, Kp,meas, in the individual samples were well correlated with the compounds’ sub-cooled liquid vapor pressure, pLo. Values of Kp,meas varied by about two orders of magnitude for any given value of vapor pressure. These variations in gas/particle partitioning of PAHs were higher than the estimated systematic and random error of Kp,meas and are related to the aerosol characteristics and sampling conditions. Stepwise multiple linear regression analysis (MLR) of the pooled data, which included pLo at 25°C, temperature, fOC and fEC as independent variables, explains 84.5% of the variability of the partition coefficients. This is higher than the explained variance when pLo is used as a single parameter (77.5%). The relative importance of each variable for prediction of PAH partition coefficient is determined by partial coefficients of determination. Vapor pressure at 25°C (RpoL2=0.84) and temperature (RT2=0.21) are the two most important predictors followed by fEC (RfEC2=0.12) and fOC (RfOC2=0.038). Both EC and OC carbon are important predictors of gas/particle partitioning of PAHs, with EC being a better predictor. Because EC is highly correlated with (and is a good tracer of) primary combustion-generated OC, this result suggests that PAHs more readily sorb on combustion-generated aerosol containing EC. Enrichment of the indoor aerosol in non-combustion OC suggests that sorption of PAHs is more important in the indoor air compared to the outdoor air. The MLR developed in this work will improve prediction of gas/particle partitioning of PAHs in indoor and outdoor air.
The U.S. Environmental Protection Agency and the California Air Resources Board studied the exposures of 51 residents of Los Angeles, California, to 25 volatile organic chemicals (VOCs) in air and drinking water in 1987. A major goal of the study was to measure personal, indoor, and outdoor air concentrations, and breath concentrations of VOCs in persons living in households that had previously been measured in 1984. Other goals were to confirm the marked day-night and seasonal differences observed in 1984; to determine room-to-room variability within homes; to determine source emission rates by measuring air exchange rates in each home; and to extend the coverage of chemicals by employing additional sampling and analysis methods. A total of 51 homes were visited in February of 1987, and 43 of these were revisited in July of 1987. The results confirmed previous TEAM Study findings of higher personal and indoor air concentrations than outdoor concentrations of all prevalent chemicals (except carbon tetrachloride); higher personal, indoor, and outdoor air concentrations in winter than in summer; and (in winter only) higher outdoor concentrations at night than in the daytime. New findings included the following: (1) room-to-room variability of 12-hour average concentrations was very small, indicating that a single monitor may be adequate for estimating indoor concentrations over this time span; (2) "whole-house" source emission rates were relatively constant during both seasons, with higher rates for odorous chemicals such as p-dichlorobenzene and limonene (often used in room air fresheners) than for other classes of chemicals; (3) breath concentrations measured during morning and evening were similar for most participants, suggesting the suitability of breath measurements for estimating exposure in the home; (4) limited data obtained on two additional chemicals-toluene and methylene chloride-indicated that both were prevalent at fairly high concentrations and that indoor air concentrations exceeded outdoor concentrations by a factor of about three.
The Particle Total Exposure Assessment Methodology (PTEAM) study provided the opportunity to test methodologies for measuring personal and microenvironmental PM10 and PM2.5 concentrations in a full-scale probability-based sample of 178 persons and homes in Riverside, California during the fall of 1990. The purpose of the study was to estimate frequency distributions of exposure to PM10, PM2.5, and selected elements in an urban population. Quality control samples and analyses were used to evaluate method performance. These included collocated sample collection, field and lab blank filters, sampler and balance field audits, and intra- and interlaboratory replicate elemental analyses. A portion of the study was also designed to include side-by-side operation of the personal and microenvironmental samplers with reference method (high-volume and dichotomous) samplers to provide an evaluation of method comparability. Over 95% of the approximately 2,900 scheduled samples were collected and analyzed, with very few losses due to equipment failure. The method limit of detection for the personal and microenvironmental monitor PM10 sampling was 8 micrograms/m3. Mean relative standard deviations (RSDs) of 2% to 8% were obtained for collocated personal and microenvironmental samples. Sampler flow rates were within the +/- 10% accuracy criterion during two field audits. Balances operated in a specially designed mobile laboratory were within specified tolerances for precision (+/- 4 micrograms) and accuracy (+/- 50 micrograms). Elemental analysis accuracy was measured with standard reference materials with biases ranging from 2% to 7%. Measurement precision for most elements ranged from 2.5% to 25% mean RSD. Personal and microenvironmental samplers gave median PM10 concentrations that were approximately 9% higher than the dichotomous sampler and 16% higher than the high-volume sampler across 96 monitoring periods at a fixed outdoor location.
The PTEAM Study was the first large-scale probability-based study of personal exposure to particles. Sponsored by the U.S. Environmental Protection Agency (EPA) and the Air Resources Board of California, it was carried out by the Research Triangle Institute (RTI) and the Harvard University School of Public Health (HSPH). HSPH designed and constructed a 4-lpm, battery-operated personal monitor for inhalable particles (PM10) that could be worn comfortably for up to 14 hours by persons from 10 to 70 years old. The monitor was worn for two consecutive 12-hour periods (day and night) during the fall of 1990 by 178 participants representing 139,000 nonsmoking residents of Riverside, California. Nearly identical monitors were employed to collect concurrent indoor and outdoor samples. The monitors were equipped with a different sampling nozzle to collect fine particles (PM2.5). Population-weighted daytime personal PM10 exposures averaged 150 +/- 9 (SE) micrograms/m3, compared to concurrent indoor and outdoor concentrations of 95 +/- 6 micrograms/m3. This suggested the existence of excess mass near the person, a "personal cloud" that appeared related to personal activities. Fourteen of 15 prevalent elements also were evaluated in the personal samples. The two major indoor sources of indoor particles were smoking and cooking; even in these homes, however, more than half of the indoor particles came from outdoors, and a substantial portion of the indoor particles were of undetermined indoor origin. Outdoor concentrations near the homes were well correlated with outdoor concentrations at the central site, supporting the idea of using the central site as an indicator of of ambient concentrations over a wider area. Indoor concentrations were only weakly correlated with outdoor concentrations, however, and personal exposures were even more poorly correlated with outdoor concentrations. Elemental profiles were obtained for environmental tobacco smoke (ETS) (major contributions from potassium and chlorine) and cooking emissions (aluminum, iron, calcium, and chlorine). These profiles can be used in future source apportionment studies.
Volatile organic emissions from particleboard, medium density fibreboard (MDF) and office furniture have been measured in dynamic environmental chambers, both small and room-sized. Characterisation of product emission properties in small chambers was possible when inter- and intra-sheet variations were considered. Formaldehyde emission factors for all products were approximately double European low-emission specifications and did not decay to the latter for several months. Long-term emission behaviour could not be predicted from short-term measurements. Volatile organic compounds (VOC) emissions were low for the MDF product, higher for particleboard, and highest for laminated office furniture. The compounds emitted differed from those reported in other countries. VOC emissions from the sheet products decreased more quickly than formaldehyde, reaching low levels within two weeks, except for MDF which was found to become a low-level source of hexanal after several months.
A major objective of the National Human Exposure Assessment Survey (NHEXAS) performed in Arizona was to conduct residential environmental and biomarker measurements of selected pesticides (chlorpyrifos, diazinon), volatile organic compounds (VOCs; benzene, toluene, trichloroethene, formaldehyde, 1,3-butadiene), and metals for total human exposure assessments. Both personal (e.g., blood, urine, dermal wipes, 24 h duplicate diet) and microenvironmental (e.g., indoor and outdoor air, house dust, foundation soil) samples were collected in each home in order to describe individual exposure via ingestion, inhalation, and dermal pathways, and to extrapolate trends to larger populations. This paper is a preliminary report of only the microenvironmental and dermal wipe data obtained for the target pesticides and VOCs, and provides comparisons with results from similar studies. Evaluations of total exposure from all sources and pathways will be addressed in future papers. The pesticides and VOCs all showed log-normal distributions of concentrations in the Arizona population sampled, and in most cases were detected with sufficient frequency to allow unequivocal description of the concentration by media at the 90th, 75th, and 50th (median) percentiles. Those combinations of pollutant and media, in which a large fraction of the measurements were below the detection limit of the analysis method used, included trichloroethene, 1,3-butadiene, and formaldehyde in outdoor air; chlorpyrifos and diazinon in outdoor air; and diazinon in dermal and window sill wipes. In general, indoor air concentrations were higher than outdoor air concentrations for all VOCs and pesticides investigated, and VOC levels were in good agreement with levels reported in other studies. In addition, the agreement obtained between co-located VOC samplers indicated that the low-cost diffusional badges used to measure concentrations are probably adequate for use in future monitoring studies. For the pesticides, the median levels found in indoor samples agreed well with other studies, although the levels corresponding to the upper 0.1-1% of the population were considerably higher than levels reported elsewhere, with indoor air levels as high as 3.3 and 20.5 microg/m3 for chlorpyrifos and diazinon, respectively. These data showed excellent correlation (Pearson and Spearman correlation coefficients of 0.998 and 0.998, respectively) between chlorpyrifos in indoor air and in the corresponding dermal wipes, and relatively poor correlation between chlorpyrifos in dust (microg/g or microg/ml) and dermal wipes (Pearson=0.055 microg/g and 0.015 microg/m2; Spearman=0.644 microg/g and 0.578 microg/m2). These data suggest the importance of dermal penetration of semi-volatiles as a route of residential human exposure.
Information about the ratio between indoor and outdoor concentrations (IO ratios) of air pollutants is a crucial component in human exposure assessment. The present study examines the relationship between indoor and outdoor concentrations as influenced by the combined effect of time patterns in outdoor concentrations, ventilation rate, and indoor emissions. Two different mathematical approaches are used to evaluate IO ratios. The first approach involves a dynamic mass balance model that calculates distributions of transient IO ratios. The second approach assumes a linear relationship between indoor and outdoor concentrations. We use ozone and benzene as examples in various modeling exercises. The modeled IO ratio distributions are compared with the results obtained from linear fits through plots of indoor versus outdoor concentrations.
Indoor air quality problems resulting from emission of volatile organic compounds (VOCs) have become an issue of increasing concern. Factors known to affect VOC levels in indoor air include: ventilation rate, occupant activities, and emissions from building and furnishing materials. In this research, VOC emissions from particleboard and medium density fiberboard (MDF) were measured in small stainless steel chambers (53 L) during a 4-day period. A protocol was developed to obtain new and representative samples and to minimize contamination of the samples during collection, preparation, and shipment to the laboratory. Samples were collected from 53 of the 61 U.S. mills that produce particleboard and MDF. Each mill identified the predominant tree species used to manufacture the panels. The laboratory tests were conducted at 45 percent relative humidity and used a gas chromatograph and a mass selective detector to identify and quantify VOC compounds. The predominant compounds identified in emissions from the particleboard and MDF samples were terpenes and aldehydes. Small straight-chain alcohols and ketones were also found. This study describes the terpene emission data. Quantified terpenes included α- and β-pinene, camphene, 3-carene, p-cymene, limonene, and borneol. Terpene emissions accounted for between 7 and 21 percent of the total VOC emissions, calculated as α-pinene. The highest terpene emissions were observed from particleboard samples manufactured from pines other than southern pine. For particleboard, terpene emissions were largely related to the extractive content of the wood species. The terpenes were almost completely absent in emissions from MDF samples, which indicates that differences in the manufacturing of MDF compared with the manufacturing of particleboard may have considerably affected emissions. After 4 days, the terpene emissions from all particleboard samples decreased to between 20 and 70 percent of their initial values.
Ozone-induced formation of aldehydes was studied on the surface and in the gas phase above carpets and on carpet components. Samples of four carpets were exposed to 100 ppb ozone. Emission rates of aldehydes and other organic compounds were measured from exposed and unexposed samples. Surface interactions of ozone with carpets produced C1-C13 n-aldehydes and several unsaturated aldehydes. Total aldehyde emission rates increased markedly with ozone exposure, from 1 to 70 microg m(-2) h(-1) for unexposed samples, to 60-800 microg m(-2) h(-1) during exposure. One exposed sample emitted large amounts of 2-nonenal (180-230 microg m(-2) h(-1)), a compound with a low odor threshold. Material balance modeling of a residence with this high emitting carpet suggests (1) that the concentration of 2-nonenal would be well above its odor threshold even in areas with only moderate ambient ozone levels and (2) that odorous levels of 2-nonenal could persist for years. Reactions of ozone with gas-phase primary emissions from carpet significantly reduced the levels of 4-phenylcyclohexene and produced small amounts of branched ketones. Separately measured patterns of aldehyde emissions from ozone exposure of linseed and tung oils were similar but not identical to those observed from ozone-exposed carpets.
To better understand the factors that control indoor pollutant concentrations, we developed a model describing mass transport and uptake of reactive gases on carpeting. First, an existing model of particle deposition from turbulent flow to indoor surfaces was extended to include surface resistance to the uptake of reactive gases. This model parameterizes surface resistance in terms of the pollutant-surface reaction probability,. We develop an approach for predicting the effective reaction probability of carpet from its geometric parameters and from experimentally measured uptake probabilities of ozone on carpet fibers, gamma(f), and carpet backing, gamma(b). A comparison of predictions with empirical data for several carpet samples shows good agreement, with a typical value of gamma similar to 10(-5). For this value of gamma and for typical turbulent indoor airflow conditions (i.e., friction velocity in the range 0.3-3 cm s(-1)), the deposition velocity of ozone I onto carpet should lie in the range 0.016-0.064 cm s(-1), values that are consistent with field measurements. Owing to its higher reaction probability, carpet backing is predicted to consume approximately the same amount of ozone as carpet fibers, even though the available surface area of the fibers is much larger.
Description
The result of a changing technology, STP 904 presents the latest information on air infiltration. There are 23 papers in this book which is divided into four sections: residential; commercial and industrial; techniques for measurements and infiltration reduction; and analysis.
Scenarios have been developed and calculations made for aldehyde production from primary and secondary sources within the stable boundary layer after sunset until several hours after sunrise the next day. The sensitivities of production of formaldehyde and several higher molecular weight aldehydes from alkenes to variations in O3 and NO3 concentrations are estimated. Production of aldehydes from alkenes emitted during the 2100h to 0600h period is calculated within the 2100h to 0600h period and the 0600h to 0900h period. The relative production of the aldehydes from primary vehicular sources relative to secondary atmospheric reactions is considered. The contribution from the OH reactions with alkanes to aldehyde production in the 0600h to 0900h period also is estimated.
Atmospheric hydrocarbons have an important influence on the chemistry of
the polluted lower atmosphere. Aromatic hydrocarbons or benzene
derivatives comprise about 25-40% of gasoline in the US1 and
they are widely employed as solvents. Toluene is the most commonly used
aromatic hydrocarbon and is often the most abundant of all non-methane
hydrocarbons in urban atmospheres. Typical urban toluene concentrations
range from 1 to 50 p.p.b. (parts per 109)2,3 and
clean-air concentrations up to 0.4 p.p.b. have been
reported4. The aromatic hydrocarbons are destroyed by
reaction with atmospheric hydroxyl radical (HO) and toluene remains in
the atmosphere for about 50 daylight hours before reacting. Despite
extensive study, toluene's reaction products are poorly
understood5. Many reaction products have been identified, but
most of these are ring-addition or side-chain oxidation products which
retain the aromatic character of toluene. We have conducted a thorough
study of toluene's oxidation products in simulated atmospheric
conditions and present here an account of the products found and outline
their probable formation and destruction mechanisms.
EPA's TEAM Study has measured exposures to 20 volatile organic compounds in personal air, outdoor air, drinking water and the breath of 355 persons in NJ, in the fall of 1981. The NJ residents were selected by a probability sampling scheme to represent 128,000 inhabitants of Elizabeth and Bayonne. Participants carried a personal monitor to collect two 12-h air samples and gave a breath sample at the end of the day. Two consecutive 12-h outdoor air samples were also collected on identical Tenax cartridges in the back yards of 90 of the participants. About 3000 samples were collected, of which 1000 were quality control samples. Eleven compounds were often present in air. Personal exposures were consistently higher than outdoor concentrations for these chemicals, and were sometimes ten times the outdoor concentrations. Indoor sources appeared responsible for much of the difference. Breath concentrations also usually exceed outdoor concentrations, and correlated more strongly with personal exposures than with outdoor concentrations. Some activities (smoking, driving, visiting dry cleaners or service stations) and occupations (chemical, paint and plastics plants) were associated with significantly elevated exposures and breath levels for certain toxic chemicals.
This paper presents the design and evaluation of a tube-type diffusive sampler, the Personal Aldehydes and Ketones Sampler (PAKS). The sampler employs dansylhydrazine (DNSH)-coated solid sorbent to collect aldehydes and ketones (carbonyls). The DNSH-carbonyl derivatives are analyzed using a sensitive HPLC-fluorescence technique. The PAKS was evaluated using test atmospheres containing eight carbonyls for a range of face velocity, temperature, relative humidity, concentration, and sampling duration. The PAKS was also evaluated in the field by comparing results obtained from the PAKS method to those from a conventional DNPH method. The evaluation results indicate that the PAKS is a valid passive sampler for 24−48-h collection of carbonyls in indoor, outdoor, or personal air. The fluorescence detection of DNSH-carbonyl derivatives substantially enhances the sensitivity of the PAKS method as compared to the DNPH method when the sampling rates for the two methods are comparable. The PAKS exposure detection limits for the eight tested carbonyls of relatively large health risk importance (formaldehyde, acetaldehyde, acetone, acrolein, propionaldehyde, crotonaldehyde, benzaldehyde, and hexaldehyde) range from 0.4 to 1.6 (ppb) (day).
The performance of the 3M 3520 organic vapor monitor (OVM) as a tool for monitoring inhalation exposures to volatile organic compounds (VOCs) in nonoccupational community environments was evaluated by using combined controlled test atmospheres of benzene, 1,3-butadiene, carbon tetrachloride, chloroform, 1,4-dichlorobenzene, methylene chloride, styrene, tetrachloroethylene, and toluene. Eight OVMs were simultaneously exposed to concentrations of 10, 20, and 200 μg/m3 in combination with temperatures of 10, 25, and 40 °C and relative humidities of 12, 50, and 90% for 24 h. The results of this study indicate that the performance of the 3520 OVM is compound-specific and depends on concentration, temperature, and humidity. With the exception of 1,3-butadiene under most conditions and styrene and methylene chloride at very high relative humidities, recoveries showed a negative bias as compared to calculated chamber concentrations but were generally within ±25% of theory, indicating that the 3520 OVM can be effectively used over the range of concentrations and environmental conditions tested with a 24-h sampling period. Increasing humidities resulted in increasing negative bias from full recovery. Reverse diffusion experiments conducted at 200 μg/m3 and five temperature/humidity combinations indicated diffusion losses only for 1,3-butadiene, methylene chloride, and styrene under increased humidity conditions. The recovery rates reported in this study can be used for estimating measurement biases when using OVMs for indoor, outdoor, and personal air monitoring of VOCs in community environments.
A dynamic exposure chamber was constructed to evaluate the performance of the 3M 3520 organic vapor monitor (3520 OVM, 3M Co., St Paul, MN) when exposed during 24 h to combined test atmospheres of benzene, 1,3-butadiene, carbon tetrachloride, chloroform, 1,4-dichlorobenzene, methylene chloride, styrene, tetrachloroethylene, and toluene at target concentrations of 10, 20, and 200 μg/m3 in combination with temperatures of 10, 25, and 40 °C and relative humidities of 12, 50, and 90%. These conditions are generally representative of the range of community air environments, both indoor and outdoor. The system consists of five distinct units: (i) dilution air delivery, (ii) humidification, (iii) VOC generation and delivery, (iv) mixing chamber, and (v) exposure chamber. High-emission permeation tubes were utilized to generate the target VOCs. Both the target temperatures and humidities were achieved and maintained for multiple consecutive days. The variation of the temperature in the exposure chamber was controlled within ±1 °C, while relative humidity was controlled within ±1.5% at 12% RH, ±2% at 50% RH, and ±3% at 90% RH. Under constant preset temperatures and stable nitrogen flow through the VOC generation unit, various temporal patterns of permeation rates were observed over time. The lifetimes and permeation rates of the tubes differed by compound, length of the tube, and manufacturer. For tubes with a long shelf life, an initial conditioning period of up to 50 days in the VOC generation unit was necessary before permeation rates became stable. A minimum of 3 days of reconditioning was required when the tubes were stored in the refrigerator before they were used again. 1,3-Butadiene tubes had a short shelf life, and the permeation rates changed significantly and relatively quickly over time; however, the rates could be estimated by using a best-fit equation for the tube weight loss data for each exposure period. By closely monitoring weight loss over time, the permeation tubes could be used for delivering low and stable concentrations of VOCs over multiple months.
This paper presents a new database of carbonyl emission factors for commonly used cookstoves in China. The emission factors, reported both on a fuel-mass basis (mg/kg) and on a defined cooking-task basis (mg/task), were determined using a carbon balance approach for 22 types of fuel/stove combinations. These include various stoves (e.g., traditional, improved, brick, and metal, with and without flue) using different species of crop residues and wood, kerosene, and several types of coals and gases. The results show that all the tested cookstoves produced formaldehyde and acetaldehyde and that the vast majority of the biomass stoves produced additional carbonyl compounds such as acetone, acrolein, propionaldehyde, crotonaldehyde, 2-butanone, isobutyraldehyde, butyraldehyde, isovaleraldehyde, valeraldehyde, hexaldehyde, benzaldehyde, o-tolualdehyde, m,p-tolualdehyde, and 2,4-dimethylbenzaldehyde. Carbonyls other than formaldehyde and acetaldehyde, however, were rarely generated by burning coal, coal gas, and natural gas. Kerosene and LPG stoves generated more carbonyl compounds than coal, coal gas, and natural gas stoves, but less than biomass stoves. Indoor levels of carbonyl compounds for typical village houses during cooking hours, estimated using a mass balance model and the measured emission factors, can be high enough to cause acute health effects documented for formaldehyde exposure, depending upon house parameters and individuals' susceptibility.
Formaldehyde (HCHO) is a toxic air contaminant released indoors from pressed-wood materials and numerous consumer products. Formaldehyde emission data are needed for modeling of indoor personal exposures, health risks, and risk reduction measures. This study determined HCHO emission rates from 55 diverse materials and consumer products under two realistic chamber test conditions, using both time-integrated and continuous real-time measurements. Among dry products, relatively high emissions were found from bare pressed-wood materials made with urea-formaldehyde (UF) resins, and from new (unwashed) permanent press fabrics. UF materials with paper, vinyl, laminate, and other coatings showed HCHO emissions lower by about a factor of 10 than those from bare UF materials. Among wet products, an acid-cured floor finish showed the highest HCHO emissions, greatly exceeding those of any dry product even 24 h after application. Fingernail polish and hardener showed relatively high emission rates, and latex paint and wallpaper relatively low emission rates, but these products emit similar amounts of HCHO because of widely different surface areas of application. Acid-cured finishes, and personal activity patterns and exposures during application of wet products, are key areas for further study.
Aldehyde emissions are widely held responsible for the acrid after-odor of drying alkyd-based paint films. The aldehyde emissions from three different alkyd paints were measured in small environ-mental chambers. It was found that, for each gram of alkyd paint applied, more than 2 mg of aldehydes (mainly hexanal) were emitted during the curing (drying) period. Since no measurable hexanal was found in the original paint, it is suspected that the aldehydes emitted were produced by autoxidation of the unsaturated fatty acid esters in the alkyd resins. The hexanal emission rate was simulated by a model assuming that the autoxidation process was controlled by a consecutive first-order reaction mechanism. Using the emission rate model, indoor air quality simulation indicated that the hexanal emissions can result in prolonged (several days) exposure risk to occupants. The occupant exposure to aldehydes emitted from alkyd paint also could cause sensory irritation and other health concerns.
In a busy street in Central Copenhagen winter mean concentrations (ppbv) were for formic acid, (0.7 ± 0.3); acetic acid, (1.2 ± 0.5); formaldehyde, (2.6 ± 0.7); acetaldehyde, (1.0 ± 0.7); and acetone, (1.0 ± 0.5). Simultaneous measurements at a semi-rural site 30 km west of Copenhagen showed mean concentrations (ppbv) of: formic acid, (0.6 ± 0.3); acetic acid, (1.0 ± 0.5); formaldehyde, (0.9 ± 0.5); acetaldehyde, (0.7 ± 0.4); and acetone, (0.9 ± 0.4).The similar concentrations of formic acid and acetic acid at the two sites in Denmark when NOy concentrations were one order of magnitude lower at the semi-rural site indicate that primary emission from automobiles was not an important source of the carboxylic acids. In a busy street in Brussels, Belgium summer mean concentrations (ppbv) were for formic acid, (3.6 ± 1.6) and acetic acid, (4.0 ± 2.0). Weaker diurnal variation of formic acid and acetic acid than of the directly emitted NOy and CO in both Copenhagen and Brussels further support sources of the carboxylic acids other than car traffic.For formaldehyde the strong correlations with gas NOy and CO indicate that direct emission from automobile is a source. Acetone shows similar concentrations at the urban and semirural sites and weak correlations with CO and gas NOy which indicate other sources than traffic emission.For acetone and the carboxylic acids the similar concentrations at the urban and semi-rural site may be explained by a regional photochemical source, i.e. oxidation of reactive hydrocarbons in polluted air masses carried to the region by long-range transport.
The current knowledge of the gas-phase reactions occurring in the troposphere for alkanes, alkenes, alkynes, oxygenates and aromatic hydrocarbons and their photooxidation products is reviewed, and areas of uncertainty identified.
Ambient levels of six carbonyls, formaldehyde (⩽70 ppb), acetaldehyde (⩽56 ppb), propanal, (⩽37 ppb), n-butanal (⩽8 ppb), 2-butanone (⩽15 ppb) and benzaldehyde (⩽2 ppb) have been measured in samples collected at several locations in the Los Angeles area. Reasonable agreement for formaldehyde, but significant discrepancies for other carbonyls, were found when comparing carbonyl/CO ratios measured at a near-source location to those derived from emission inventories, e.g., total carbonyl emission rate of ∼ 30 tons/day from measured ratios vs. ∼ 70–80 tons/day from inventory data. Comparison of carbonyl/CO ratios at the smog receptor and near-source locations indicates that photochemical production of carbonyls, up to 500 tons/day during smog episodes, dominates over direct emissions in controlling carbonyl levels in Los Angeles air.
The average concentrations of 45 fine-particle aerosol, VOC and aldehyde species measured in 10 Boise, ID, residences in wintertime have been apportioned according to their contributions from all inside sources and all outside sources. In most of the homes the indoor source contributions was dominant for-fine particle S Si, Ca and Fe, while the infiltration contribution was dominant for fine-particle S, K, Pb, Zn, mass and extractable organic matter. Indoor contributions to individual VOCs were frequently very large at a few residences and negligible at the others. All aldehydes were dominated by indoor sources. The apportionment results have also been expressed as indoor source strengths.
The objective of this study was to characterize the emissions of air pollutants from incense burning in a large environmental test chamber. Air pollutants emitted from ten types of commonly used incense manufactured in different regions were compared. The target pollutants included particulate matters (PM10, PM2.5), volatile organic compounds (VOCs), carbonyls, carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides (NOx), methane (CH4) and non-methane hydrocarbon (NMHC). The particulate matters emitted from all the incense significantly exceeded the Recommended Indoor Air Quality Objectives for Office Buildings and Public Places in Hong Kong (HKIAQO). The CO peak levels of seven incense types greatly exceeded the HKIAQO standard. The formaldehyde concentrations of six types of incense were higher than the HKIAQO. The highest formaldehyde level exceeded the standard by 2 times. The results indicated that the concentrations of benzene, toluene, methyl chloride and methylene chloride significantly increased with the burning of all incense tested. In addition, the benzene concentrations of all tested incense were significantly higher than the HKIAQO standard. Although Incense 2 and 6 were claimed to be environmental friendly, the quantity of the pollutants emitted was not observed to be lower than the others. It was observed that when comparing the gas pollutant emission factors between two major incense categories (i.e. traditional and aromatic), the traditional incense (i.e. Incense 1−6) had relatively higher values than aromatic incense (i.e. Incense 7−9). Generally, it was found that the VOCs emitted sequence was aromatic incense>tradition incense>church incense (i.e. Incense 10). However, the carbonyl compounds emission sequence was traditional incense>aromatic incense>church incense. The results show that incense burning is one of the important indoor air pollution sources for PM, CO and VOCs.
A general mathematical model is presented for predicting
the concentrations of chemically reactive compounds in indoor air. The model accounts for the effects of ventilation, filtration, heterogeneous removal, direct
emission, and photolytic and thermal chemical reactions.
The model is applied to the induction of photochemically
reactive pollutants into a museum gallery, and the predicted
NO, NO_x-NO, and O_3 concentrations are compared to measured data. The model predicts substantial production
of several species due to chemical reaction, including
HNO_2, HNO_3, NO_3, and N_2O_5. Circumstances in which homogeneous chemistry may assume particular importance
are identified and include buildings with glass walls, indoor combustion sources, and direct emission of olefins.
The release of many volatile organic chemicals (VOCs) into the ambient environment is a necessary outcome of their use. Monitoring activities have generated a significant body of VOC data widely scattered in scientific journals and reports. Critics charge that too few chemicals are monitored, the data generated are of varying and often questionable quality, and the results are not readily available to users. In 1980, EPA recognized the need to organize the available data into a single, cohesive format so their quantity, quality, and significance could be assessed. A VOC national ambient data base was first prepared in the early 1980s and published by EPA. In 1986, when the data base needed to be expanded to include the large amount of ambient VOC data published since 1980, EPA contracted to upgrade and expand the early study. Concurrently, powerful personal computers (PCs) that could be conveniently sued for such data bases became available. As a result of this study, outdoor as well as indoor data are now available in a unified form for PCs and can be used to screen for many environmental problems, including exposure to VOCs. Here we present a first look at this comprehensive national VOC data basemore » and construct a picture of VOC distribution in the environment.« less
The formation of aldehydes and organic acids was examined for the gas- phase reactions of ozone with unsaturated VOCs. Formaldehyde and formic acid were produced via the reaction of ozone with each of the three selected unsaturated VOCs: styrene, limonene, and 4-vinylcyclohexene. In addition, benzaldehyde was detected in the styrene-ozone-air reaction system, and acetic acid was found in the limonene-ozone-air system. The study also examined the gas-phase reactions involving formaldehyde, ozone, and nitrogen dioxide and found the formation of formic acid, suggesting that the nitrate radical may play an important role in converting formaldehyde into formic acid. Experiments for all the reactions were conducted by using a 4.3-m3 Teflon chamber. Since the conditions and chemicals employed in the reactions were similar to those for indoor environments, the results from this study may be extrapolated to typical indoor situations and support indications from previous studies that certain aldehydes and organic acids could be generated by indoor chemistry.
Simultaneous indoor and outdoor measurements of aldehydes were made at 6 residential houses located in a suburban New Jersey area during the summer of 1992. Each house was measured for six days and controlled for ventilation and gas combustion conditions during the study. Formaldehyde, acetaldehyde, and seven other aldehydes were identified in the residential air. The study presents the first measurements of nine aldehyde species in both indoor and outdoor air. The total concentrations of the nine aldehydes were 19.12 +/- 10.88 ppb outdoors and 62.57 +/- 21.75 ppb indoors. Formaldehyde was the most abundant aldehyde. Except for propionaldehyde, the indoor concentrations were found higher than the outdoor concentrations for all the other compounds, indicating the presence of significant indoor sources such as direct emissions and indoor chemical formation. Ozone concentrations were measured simultaneously during the study, and it was observed that several aldehydes can be generated through indoor ozone chemistry. The study provided evidence to support laboratory results obtained by other investigators that predicted aldehyde generation through indoor ozone chemistry. The residential exposures to formaldehyde and total aldehydes were assessed based upon some assumptions, and the outdoor exposures were negligible compared to the indoor exposures.
An Eulerian photochemical air quality model is described
for the prediction of the atmospheric transport and
chemical reactions of gas-phase toxic organic air pollutants. Model performance was examined in the Los Angeles, CA, area over the period August 27-28, 1987. The organic compounds were drawn from a list of 189 species selected for control as hazardous air pollutants in the Clean Air Act amendments of 1990. The species considered include benzene, various alkylbenzenes, phenol, cresols, 1,3- butadiene, acrolein, formaldehyde, acetaldehyde, and
perchloroethylene among others. It is found that photochemical generation contributes significantly to form-aldehyde, acetaldehyde, acetone, and acrolein concentrations for the 2-day period studied. Phenol concentrations are dominated by direct emissions, despite the existence of a pathway for atmospheric formation from benzene oxidation. The finding that photochemical production
can be a major contributor to the total concentrations of
some toxic organic species implies that control programs
for those species must consider more than just direct
emissions.
The toluene oxidation process was studied by blacklight irradiation of
1-10ppm each of toluene and oxides of nitrogen in 22-liter pyrex flasks,
in zero-air at 50% relative humidity. The products were recovered from
the walls by extraction with methanol or dichloromethane. Some gas-phase
products were recovered in the solvent as well. The extracts were
analyzed on a Finnigan MAT triple stage quadrupole mass
spectrometer/data system by direct probe injection. Once their molecular
weights were determined, the products were fragmented by
collision-dissociation (CID) in the middle quadrupole to produce
characteristic daughter ions. To assist in the spectral interpretation,
toluene in three isomeric forms was subjected to simulated atmospheric
reaction. In addition to normal (H8) toluene, methyl-deuterated (D3) and
per-deuterated (D8) toluene were used. This study confirmed the
existence of a number of products identified in past studies, confirmed
the formation of some products which have been hypothesized in several
proposed mechanisms for toluene oxidation, identified a number of
previously unidentified and unproposed products.
As part of a study of health effects of sulfur dioxide and particulate matter, we have established a cohort of adults 25 to 74 yr of age in 6 communities who will be followed prospectively. At the conclusion of our first cycle of measuring the health of adults in 6 sites we found that, although we used different sampling frames, our samples were close to the distribution shown in the U.S. Census for age, sex, and occupation, with the possible exception of one city. Analysis of the cross-sectional data indicated that for both age- and height-adjusted values for forced expiratory volume in 1 s and for selected rates of various respiratory symptoms standardized for age, differences among smoking groups were apparent. Differences in these parameters between sites suggest trends that were associated with levels of pollution. Further analyses of the prospective data currently being collected will be required before definitive statements can be made about the effect of specific levels of exposure.
Environmental Protection Agency TEAM (Total Exposure Assessment Measurement) Studies have measured exposures of about 800 persons to 25 volatile organic compounds (VOCs) and exposures of about 300 persons to 32 pesticides. These persons were selected to represent more than 1 million residents of industrial manufacturing cities such as Bayonne and Elizabeth, New Jersey, and Los Angeles, California; cities with light industry, such as Greensboro, North Carolina, and Baltimore, Maryland; rural areas such as Devils Lake, North Dakota; and cities with high pesticide use such as Jacksonville, Florida, as well as low-to-moderate pesticide use such as Springfield, Massachusetts. The TEAM data provide an opportunity to estimate the risks from airborne exposure to a number of suspected carcinogens for a substantial number of persons residing in a wide variety of urban, suburban, and rural areas. Because all of the TEAM Studies measured outdoor concentrations near the homes of the participants, it is possible to apportion the risks between outdoor and indoor sources. Upper-bound lifetime risks of cancer are calculated for both indoor and outdoor sources of 12 VOCs and about 23 pesticides measured in the TEAM Studies. These risk calculations are supplemented by calculations based on other studies for some additional pollutants, including radon and environmental tobacco smoke. The relationship of these upper-bound risk estimates to "best-guess" values is discussed. Sharper estimates of risk based on identifying population subgroups exposed to major sources are also discussed. Important gaps in our knowledge of exposure measurements are identified, e.g., particulates (including polyaromatic hydrocarbons); 1,3-butadiene, asbestos, chromium, cadmium, arsenic, vinyl chloride, methylene chloride, and most polar organics.
The average concentrations of a large number of fine particle aerosol and VOC species measured in ten Boise, Idaho, residences in wintertime have been apportioned according to their contributions from all inside sources and all outside sources, regarded as two composite source categories. Air change rates for the residences were in the range 0.2-0.8 hr-1. None of the residences had obvious major indoor sources (smokers, woodburning appliances, etc.). The two category apportionment was accomplished through use of the single chamber mass balance indoor air quality model given by Dockery and Spengler. The method depends on the availability of average concentrations measured outside each residence during the same sampling periods used for the inside measurements, and on the ability to identify one or more species that have negligible indoor sources. Calculated infiltration factors (the indoor/outdoor ratio in the absence of indoor sources) for fine particle species averaged 0.5, and varied in a reasonably way with measured air change rates, essentially independent of species. Infiltration factors for the VOCs were indistinguishable from unity. The relative importance of indoor and outdoor sources to measured indoor concentrations showed great variation between species and between residences. In most homes the indoor source contribution was dominant for fine particle Si, Ca, and Fe, while the infiltration contribution was dominant for S, K, Pb, Zn, mass, and extractable organic matter. Indoor contributions to individual VOCs were frequently very large at a few residences and negligible at the others.
For four separate periods over a 1-yr span, the concentrations of volatile organic compounds (VOCs) have been measured at a facility with a history of occupant complaints. The reported symptoms were characteristic of "sick building syndrome." This study was initiated to determine if VOC levels were higher than those measured in "complaint-free" buildings and, if so, to identify sources and other factors that might contribute to the elevated concentrations. VOCs were collected with passive samplers, using a sampling interval that lasted from 3 to 4 weeks. Following collection, the samplers were extracted, and the compounds in the extract were separated and identified using standard gas chromatographic-mass spectrometric procedures. Over 40 different organic compounds with concentrations in excess of 1 microgram/m3 were identified; several species had values greater than 100 micrograms/m3. For each of the first three sampling periods, the total concentration of VOCs detected using this methodology was in excess of 3 mg/m3. Sources of the identified compounds included cleaning products, floor wax, latex paints, and reentrained motor vehicle exhaust. However, the dominant source was the hydraulic system for the buildings' elevators. Compounds were volatilizing from the hydraulic fluid used in this system. Neither the elevator shafts nor the mechanical room housing the fluid reservoirs were vented to the outside. The problem was compounded by the relatively small amount of outside air used for ventilation at this facility (less than 6 L/sec [12 cfm]/occupant or about 1/4 air change/hr). At such low ventilation rates, compounds with strong sources can achieve high steady-state concentrations within the facility. Recommendations have been made to reduce the VOC levels at this site. Although implementing the recommendations will be costly, even a slight improvement in employee productivity will offset these costs.
Improvements in outdoor air quality that were achieved through the implementation of the Clean Air Act accentuate the quality of the indoor air as an important, if not dominant, factor in the determination of the total population exposure to air contaminants. A number of developments are adding important new determinants of indoor air quality. Energy conservation strategies require reductions in infiltration of outdoor air into buildings. New materials introduced in the construction and in the maintenance of buildings are contributing new air contaminants into the building atmosphere. Larger buildings require more and more complex ventilation systems that are less and less under the individual control of the occupants. All of these factors contribute to the current reality that indoor air contains more pollutants, and often at higher concentrations, than outdoor air. Especially in the larger buildings, it will be necessary to assure that an adequate quantity of fresh air of acceptable quality is provided to each individual space, and that no new sources of pollutants are added to a space or a whole building without appropriate adjustments in the supply of fresh air.
Seven persons volunteered to perform 25 common activities thought to increase personal exposure to volatile organic chemicals (VOCs) during a 3-day monitoring period. Personal, indoor, and outdoor air samples were collected on Tenax cartridges three times per day (evening, overnight, and daytime) and analyzed by GC-MS for 17 target VOCs. Samples of exhaled breath were also collected before and after each monitoring period. About 20 activities resulted in increasing exposure to one or more of the target VOCs, often by factors of 10, sometimes by factors of 100, compared to exposures during the sleep period. These concentrations were far above the highest observed outdoor concentrations during the length of the study. Breath levels were often significantly correlated with previous personal exposures. Major exposures were associated with use of deodorizers (p-dichlorobenzene); washing clothes and dishes (chloroform); visiting a dry cleaners (1,1,1-trichloroethane, tetrachloroethylene); smoking (benzene, styrene); cleaning a car engine (xylenes, ethylbenzene, tetrachloroethylene); painting and using paint remover (n-decane, n-undecane); and working in a scientific laboratory (many VOCs). Continuously elevated indoor air levels of p-dichlorobenzene, trichloroethylene, 1,1,1-trichloroethane, carbon tetrachloride, decane, and undecane were noted in several homes and attributed to unknown indoor sources. Measurements of exhaled breath suggested biological residence times in tissue of 12-18 hr and 20-30 hr for 1,1,1-trichloroethane and p-dichlorobenzene, respectively.
Since the early 1970s, the health effects of indoor air pollution have been investigated with increasing intensity. A large body of literature is now available on diverse aspects of indoor air pollution: sources, concentrations, health effects, engineering, and policy. This article provides a selective summary of this new information with an emphasis on health effects relevant to health care practitioners concerned primarily with immunologically mediated respiratory diseases. We address exposures associated with acute and chronic respiratory effects: tobacco smoke, nitrogen dioxide, wood smoke, and formaldehyde. The article also describes the diverse health problems experienced by workers in newer sealed office buildings. The importance of indoor concentrations in determining personal exposures to pollutants is emphasized.
EPA's TEAM Study has measured exposures to 20 volatile organic compounds in personal air, outdoor air, drinking water, and breath of approximately 400 residents of New Jersey, North Carolina, and North Dakota. All residents were selected by a probability sampling scheme to represent 128,000 inhabitants of Elizabeth and Bayonne, New Jersey, 131,000 residents of Greensboro, North Carolina, and 7000 residents of Devils Lake, North Dakota. Participants carried a personal monitor to collect two 12-hr air samples and gave a breath sample at the end of the day. Two consecutive 12-hr outdoor air samples were also collected on identical Tenax cartridges in the backyards of some of the participants. About 5000 samples were collected, of which 1500 were quality control samples. Ten compounds were often present in personal air and breath samples at all locations. Personal exposures were consistently higher than outdoor concentrations for these chemicals and were sometimes 10 times the outdoor concentrations. Indoor sources appeared to be responsible for much of the difference. Breath concentrations also often exceeded outdoor concentrations and correlated more strongly with personal exposures than with outdoor concentrations. Some activities (smoking, visiting dry cleaners or service stations) and occupations (chemical, paint, and plastics plants) were associated with significantly elevated exposures and breath levels for certain toxic chemicals. Homes with smokers had significantly increased benzene and styrene levels in indoor air. Residence near major point sources did not affect exposure.
Although official efforts to control air pollution have traditionally focused on outdoor air, it is now apparent that elevated
contaminant concentrations are common inside some private and public buildings. Concerns about potential public health problems
due to indoor air pollution are based on evidence that urban residents typically spend more than 90 percent of their time
indoors, concentrations of some contaminants are higher indoors than outdoors, and for some pollutants personal exposures
are not characterized adequately by outdoor measurements. Among the more important indoor contaminants associated with health
or irritation effects are passive tobacco smoke, radon decay products, carbon monoxide, nitrogen dioxide, formaldehyde, asbestos
fibers, microorganisms, and aeroallergens. Efforts to assess health risks associated with indoor air pollution are limited
by insufficient information about the number of people exposed, the pattern and severity of exposures, and the health consequences
of exposures. An overall strategy should be developed to investigate indoor exposures, health effects, control options, and
public policy alternatives.
All four TEAM Studies operated on the basis concepts of probability sampling and direct measurement of exposure. These concepts made possible the discovery that, for nearly all of the 50 or so targeted pollutants, personal exposures exceeded outdoor levels by large margins. The conclusion, corroborated in part by other studies around the world, is that the major sources of exposure are personal activities and consumer products. This result is at odds with most existing environmental legislation, which generally does not deal with products or with indoor air in homes, in favor of regulating "major" stationary and mobile sources. These sources, however, provide only between 2-25% of personal exposure to most of the two dozen or so toxic and carcinogenic VOCs and pesticides included in the TEAM Studies. Several official publications have accepted this point, finding that funding priorities are skewed, with lower-risk problems receiving more funding than higher-risk problems such as indoor air pollution. However, just as exposures are due to small nearby sources, control of exposures can often be instituted by small individual actions. Among these are stopping smoking, reducing or eliminating the use of moth balls and bathroom deodorizers containing p-dichlorobenzene, reducing or eliminating the use of dry-cleaned clothes or airing them out for a day, and maintaining dust-free homes.
Alkyd paint continues to be used indoors for application to wood trim, cabinet surfaces, and some kitchen and bathroom walls. Alkyd paint may represent a significant source of volatile organic compounds (VOCs) indoors because of the frequency of use and amount of surface painted. The U.S. Environmental Protection Agency (EPA) is conducting research to characterize VOC emissions from paint and to develop source emission models that can be used for exposure assessment and risk management. The technical approach for this research involves both analysis of the liquid paint to identify and quantify the VOC contents and dynamic small chamber emissions tests to characterize the VOC emissions after application. The predominant constituents of the primer and two alkyd paints selected for testing were straight-chain alkanes (C9-C12); C8-C9 aromatics were minor constituents. Branched chain alkanes were the predominant VOCs in a third paint. A series of tests were performed to evaluate factors that may affect emissions following application of the coatings. The type of substrate (glass, wallboard, or pine board) did not have a substantial impact on the emissions with respect to peak concentrations, the emissions profile, or the amount of VOC mass emitted from the paint. Peak concentrations of total volatile organic compounds (TVOCs) as high as 10,000 mg/m3 were measured during small chamber emissions tests at 0.5 air exchanges per hour (ACH). Over 90% of the VOCs were emitted from the primer and paints during the first 10 hr following application. Emissions were similar from paint applied to bare pine board, a primed board, or a board previously painted with the same paint. The impact of other variable, including film thickness, air velocity at the surface, and air-exchange rate (AER) were consistent with theoretical predictions for gas-phase, mass transfer-controlled emissions. In addition to the alkanes and aromatics, aldehydes were detected in the emissions during paint drying. Hexanal, the predominant aldehyde in the emissions, was not detected in the liquid paint and was apparently an oxidation product formed during drying. This paper summarizes the results of the product analyses and a series of small chamber emissions tests. It also describes the use of a mass balance approach to evaluate the impact of test variables and to assess the quality of the emissions data.