Levels of volatile organic compounds in homes in Dalian,China

This paper measured selected individual volatile organic compounds (VOCs), including formaldehyde, in residences in Dalian, evaluated the association between the apartment characteristics and VOC concentrations, and explored the associations between chemicals and sick building syndrome (SBS). Higher VOC concentrations were measured indoors than outdoors in summer (August to September) and winter (January to March) in Dalian, and there were no strong correlations between the indoor and outdoor concentrations of most VOCs. This indicates the dominance of indoor sources as compared to outdoor sources. Formaldehyde was the most abundant compound in this study, followed by toluene, benzene, xylene, and styrene. These pollutants increase the occurrence of SBS. Thus, the VOC levels in dwellings in Dalian should be regulated, in view of SBS risks.     

Migration of volatile organic compounds from attached garages to residences: a major exposure source

Vehicle garages often contain high concentrations of volatile organic compounds (VOCs) that may migrate into adjoining residences. This study characterizes VOC concentrations, exposures, airflows, and source apportionments in 15 single-family houses with attached garages in southeast Michigan. Fieldwork included inspections to determine possible VOC sources, deployment of perfluorocarbon tracer (PFT) sources in garages and occupied spaces, and measurements of PFT, VOC, and CO(2) concentrations over a 4-day period. Air exchange rates (AERs) averaged 0.43+/-0.37 h(-1) in the houses and 0.77+/-0.51 h(-1) in the garages, and air flows from garages to houses averaged 6.5+/-5.3% of the houses' overall air exchange. A total of 39 VOC species were detected indoors, 36 in the garage, and 20 in ambient air. Garages showed high levels of gasoline-related VOCs, e.g., benzene averaged 37+/-39 microg m(-3). Garage/indoor ratios and multizone IAQ models show that nearly all of the benzene and most of the fuel-related aromatics in the houses resulted from garage sources, confirming earlier reports that suggested the importance of attached garages. Moreover, doses of VOCs such as benzene experienced by non-smoking individuals living in houses with attached garages are dominated by emissions in garages, a result of exposures occurring in both garage and house microenvironments. All of this strongly suggests the need to better control VOC emissions in garages and contaminant migration through the garage-house interface.     

Ambient, indoor and personal exposure relationships of volatile organic compounds in Mexico City Metropolitan Area

Air pollution standards and control strategies are based on ambient measurements. For many outdoor air pollutants, individuals are closer to their sources (especially traffic) and there are important indoor sources influencing the relationship between ambient and personal exposures. This paper examines the relationship between volatile organic compounds (VOCs) measured at central site monitoring stations and personal exposures in the Mexico City Metropolitan Area. Over a 1-year period, personal exposures to 34 VOCs were measured for 90 volunteers from 30 families living close to one of five central monitoring stations. Simultaneous 24-h indoor, outdoor and central site measurements were also taken. Dual packed thermal desorption tubes and C(18) DNPH-coated cartridges were used for sampling VOCs and these were analyzed by GC/MS and HPLC, respectively. A factor analysis of the personal exposure data aided in grouping compounds by the most likely source type: vehicular (BTEX, styrene and 1,3-butadiene), secondary formed or photochemical (most aldehydes), building materials and consumer products (formaldehyde and benzaldehyde), cleaning solvents (tetrachloroethene and 1,1,1-trichloroethane), volatilization from water (chloroform and trichloroethene) and deodorizers (1,4-dichlorobenzene). Mean ambient, indoor and personal concentrations were 7/7/14 microg/m(3) for benzene, 1/3/3 for 1,3-butadiene, 6/20/20 for formaldehyde and 3/9/50 for 1,4-dichlorobenzene. Geometric mean (GM) ambient concentrations of trichloroethene and carbon tetrachloride were similar to GM personal exposures. While outdoor and indoor home GM concentrations for most vehicular related compounds (benzene, MTBE, xylenes and styrene) were comparable, the GM personal exposures were twice as high. Indoor concentrations of 1,3-butadiene, 1,1,1-trichloroethane, tetrachloroethane, chloroform, formaldehyde, valeraldehyde, propionaldehyde and n-butyraldehyde were comparable to personal exposures. For certain compounds, such as chloroform, aldehydes, toluene, 1,3-butadiene and 1,4-dichlorobenzene, GM personal exposures were more than two times greater than GM ambient measurements.     

Exposures to multiple air toxics in New York City

Efforts to assess health risks associated with exposures to multiple urban air toxics have been hampered by the lack of exposure data for people living in urban areas. The TEACH (Toxic Exposure Assessment, a Columbia/Harvard) study was designed to characterize levels of and factors influencing personal exposures to urban air toxics among high school students living in inner-city neighborhoods of New York City and Los Angeles, California. This present article reports methods and data for the New York City phase of TEACH, focusing on the relationships between personal, indoor, and outdoor concentrations in winter and summer among a group of 46 high school students from the A. Philip Randolph Academy, a public high school located in the West Central Harlem section of New York City. Air pollutants monitored included a suite of 17 volatile organic compounds (VOCs) and aldehydes, particulate matter with a mass median aerodynamic diameter 相似文献   

Passive smoking,excretion of metabolites,and health effects: results of the Leipzig's Allergy Risk Study (LARS)

Over a 5-yr period, the Leipzig's Allergy Risk Study (LARS) investigated the influence of typical indoor-contaminant burdens on the development of allergies and upper respiratory tract infections in allergy-prone children. Typical indoor volatile organic compounds (VOCs) and excretion of certain VOC metabolites in urine were measured in children 3 yr of age. Data analyses were based on parent-completed questionnaires, exposure measurements, and medical examinations. Evaluation of passive smoking was of special interest. Generally, residences with a high burden of passive smoking had higher benzene concentrations than residences inhabited by nonsmokers. Obstructive bronchitis was observed more frequently in children exposed to increased concentrations of benzene, as well as toluene, styrene, and m,p-xylene. In addition, atopic symptoms were associated with excretion of certain VOC metabolites. For example, the authors found an association between eczema and exposure to toluene and between eczema and increased excretion of the toluene metabolite S-benzylmercapturic acid. The results suggest that if an association with certain health effects is to be demonstrated, evaluation of external exposures should be supplemented with evaluations of internal exposure.     

Determinants of exposure to volatile organic compounds in four Oklahoma cities

To begin to develop generalized models for estimating personal exposure to ambient air pollutants within diverse populations, the design of the Oklahoma Urban Air Toxics Study incorporated eight dichotomous macroenvironmental and household factors that were hypothesized to be potential determinants of exposure. Personal, indoor, and outdoor samples of volatile organic compounds (VOCs) were collected over 24-h monitoring periods in 42 households, together with activity diaries and data on the participants' residences. The distributions of the VOC concentrations were moderately to highly left-censored, and were mostly bimodal. The ATSDR minimal risk level (MRL) was exceeded in a small number of the samples. Personal and indoor concentrations tended to be higher than outdoor concentrations, indicating that indoor exposures were dominated by indoor sources. However, indoor concentrations were not correlated with the permeability of the residence, suggesting that the observed indoor concentrations reflected mostly localized, short-term emissions. The influence of the eight dichotomous factors and of the presence of an attached garage was evaluated using the Wilcoxon rank-sum test and by comparison of "excursion fractions", that is, the fractions of each distributions exceeding 10% of the MRL. Dry weather and absence of children in the household were found to be associated with higher exposures in personal or indoor exposures. Given the small sample size, it is possible that these factors were confounded with unidentified household characteristics or activities that were the true determinants of exposure.     

Passive Smoking,Excretion of Metabolites,and Health Effects: Results of the Leipzig's Allergy Risk Study (LARS)

Over a 5-yr period, the Leipzig's Allergy Risk Study (LARS) investigated the influence of typical indoor-contaminant burdens on the development of allergies and upper respiratory tract infections in allergy-prone children. Typical indoor volatile organic compounds (VOCs) and excretion of certain VOC metabolites in urine were measured in children 3 yr of age. Data analyses were based on parent-completed questionnaires, exposure measurements, and medical examinations. Evaluation of passive smoking was of special interest. Generally, residences with a high burden of passive smoking had higher benzene concentrations than residences inhabited by nonsmokers. Obstructive bronchitis was observed more frequently in children exposed to increased concentrations of benzene, as well as toluene, styrene, and m,p-xylene. In addition, atopic symptoms were associated with excretion of certain VOC metabolites. For example, the authors found an association between eczema and exposure to toluene and between eczema and increased excretion of the toluene metabolite S-benzylmercapturic acid. The results suggest that if an association with certain health effects is to be demonstrated, evaluation of external exposures should be supplemented with evaluations of internal exposure.     

Personal exposure meets risk assessment: a comparison of measured and modeled exposures and risks in an urban community

Human exposure research has consistently shown that, for most volatile organic compounds (VOCs), personal exposures are vastly different from outdoor air concentrations. Therefore, risk estimates based on ambient measurements may over- or underestimate risk, leading to ineffective or inefficient management strategies. In the present study we examine the extent of exposure misclassification and its impact on risk for exposure estimated by the U.S. Environmental Protection Agency (U.S. EPA) Assessment System for Population Exposure Nationwide (ASPEN) model relative to monitoring results from a community-based exposure assessment conducted in Baltimore, Maryland (USA). This study is the first direct comparison of the ASPEN model (as used by the U.S. EPA for the Cumulative Exposure Project and subsequently the National-Scale Air Toxics Assessment) and human exposure data to estimate health risks. A random sampling strategy was used to recruit 33 nonsmoking adult community residents. Passive air sampling badges were used to assess 3-day time-weighted-average personal exposure as well as outdoor and indoor residential concentrations of VOCs for each study participant. In general, personal exposures were greater than indoor VOC concentrations, which were greater than outdoor VOC concentrations. Public health risks due to actual personal exposures were estimated. In comparing measured personal exposures and indoor and outdoor VOC concentrations with ASPEN model estimates for ambient concentrations, our data suggest that ASPEN was reasonably accurate as a surrogate for personal exposures (measured exposures of community residents) for VOCs emitted primarily from mobile sources or VOCs that occur as global "background" source pollutant with no indoor source contributions. Otherwise, the ASPEN model estimates were generally lower than measured personal exposures and the estimated health risks. ASPEN's lower exposures resulted in proportional underestimation of cumulative cancer risk when pollutant exposures were combined to estimate cumulative risk. Median cumulative lifetime cancer risk based on personal exposures was 3-fold greater than estimates based on ASPEN-modeled concentrations. These findings demonstrate the significance of indoor exposure sources and the importance of indoor and/or personal monitoring for accurate assessment of risk. Environmental health policies may not be sufficient in reducing exposures and risks if they are based solely on modeled ambient VOC concentrations. Results from our study underscore the need for a coordinated multimedia approach to exposure assessment for setting public health policy.     

Predictors of concentrations of nitrogen dioxide, fine particulate matter, and particle constituents inside of lower socioeconomic status urban homes

Air pollution exposure patterns may contribute to known spatial patterning of asthma morbidity within urban areas. While studies have evaluated the relationship between traffic and outdoor concentrations, few have considered indoor exposure patterns within low socioeconomic status (SES) urban communities. In this study, part of a prospective birth cohort study assessing asthma etiology in urban Boston, we collected indoor and outdoor 3-4 day samples of nitrogen dioxide (NO2) and fine particulate matter (PM2.5) in 43 residences across multiple seasons from 2003 to 2005. Homes were chosen to represent low SES households, including both cohort and non-cohort residences in similar neighborhoods, and consisted almost entirely of multiunit residences. Reflectance analysis and X-ray fluorescence spectroscopy were performed on the particle filters to determine elemental carbon (EC) and trace element concentrations, respectively. Additionally, information on home characteristics (e.g. type, age, stove fuel) and occupant behaviors (e.g. smoking, cooking, cleaning) were collected via a standardized questionnaire. The contributions of outdoor and indoor sources to indoor concentrations were quantified with regression analyses using mass balance principles. For NO2 and most particle constituents (except outdoor-dominated constituents like sulfur and vanadium), the addition of selected indoor source terms improved the model's predictive power. Cooking time, gas stove usage, occupant density, and humidifiers were identified as important contributors to indoor levels of various pollutants. A comparison between cohort and non-cohort participants provided another means to determine the influence of occupant activity patterns on indoor-outdoor ratios. Although the groups had similar housing characteristics and were located in similar neighborhoods, cohort members had significantly higher indoor concentrations of PM2.5 and NO2, associated with indoor activities. We conclude that the effect of indoor sources may be more pronounced in high-density multiunit dwellings, and that future epidemiological studies in these populations should explicitly consider these sources in assigning exposures.     

Outdoor, indoor, and personal exposure to VOCs in children

We measured volatile organic compound (VOC) exposures in multiple locations for a diverse population of children who attended two inner-city schools in Minneapolis, Minnesota. Fifteen common VOCs were measured at four locations: outdoors (O), indoors at school (S), indoors at home (H), and in personal samples (P). Concentrations of most VOCs followed the general pattern O approximately equal to S < P less than or equal to H across the measured microenvironments. The S and O environments had the smallest and H the largest influence on personal exposure to most compounds. A time-weighted model of P exposure using all measured microenvironments and time-activity data provided little additional explanatory power beyond that provided by using the H measurement alone. Although H and P concentrations of most VOCs measured in this study were similar to or lower than levels measured in recent personal monitoring studies of adults and children in the United States, p-dichlorobenzene was the notable exception to this pattern, with upper-bound exposures more than 100 times greater than those found in other studies of children. Median and upper-bound H and P exposures were well above health benchmarks for several compounds, so outdoor measurements likely underestimate long-term health risks from children's exposure to these compounds.     

Sources of air pollutants indoors: VOC and fine particulate species.

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.     

The influence of personal activities on exposure to volatile organic compounds

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.     

Children's exposure to volatile organic compounds as determined by longitudinal measurements in blood

Blood concentrations of 11 volatile organic compounds (VOCs) were measured up to four times over 2 years in a probability sample of more than 150 children from two poor, minority neighborhoods in Minneapolis, Minnesota. Blood levels of benzene, carbon tetrachloride, trichloroethene, and m-/p-xylene were comparable with those measured in selected adults from the Third National Health and Nutrition Examination Survey (NHANES III), whereas concentrations of ethylbenzene, tetrachloroethylene, toluene, 1,1,1-trichloroethane, and o-xylene were two or more times lower in the children. Blood levels of styrene were more than twice as high, and for about 10% of the children 1,4-dichlorobenzene levels were greater than or equal to 10 times higher compared with NHANES III subjects. We observed strong statistical associations between numerous pairwise combinations of individual VOCs in blood (e.g., benzene and m-/p-xylene, m-/p-xylene and o-xylene, 1,1,1-trichloroethane and m-/p-xylene, and 1,1,1-trichloroethane and trichloroethene). Between-child variability was higher than within-child variability for 1,4-dichlorobenzene and tetrachloroethylene. Between- and within-child variability were approximately the same for ethylbenzene and 1,1,1-trichloroethane, and between-child was lower than within-child variability for the other seven compounds. Two-day, integrated personal air measurements explained almost 79% of the variance in blood levels for 1,4-dichlorobenzene and approximately 20% for tetrachloroethylene, toluene, m-/p-xylene, and o-xylene. Personal air measurements explained much less of the variance (between 0.5 and 8%) for trichloroethene, styrene, benzene, and ethylbenzene. We observed no significant statistical associations between total urinary cotinine (a biomarker for exposure to environmental tobacco smoke) and blood VOC concentrations. For siblings living in the same household, we found strong statistical associations between measured blood VOC concentrations.     

A cancer risk assessment of inner-city teenagers living in New York City and Los Angeles

BACKGROUND: The Toxics Exposure Assessment Columbia-Harvard (TEACH) project assessed exposures and cancer risks from urban air pollutants in a population of high school teenagers in New York City (NYC) and Los Angeles (LA). Forty-six high school students participated in NYC and 41 in LA, most in two seasons in 1999 and 2000, respectively. METHODS: Personal, indoor home, and outdoor home 48-hr samples of volatile organic compounds (VOCs), aldehydes, particulate matter with aerodynamic diameter < or = 2.5 microm, and particle-bound elements were collected. Individual cancer risks for 13 VOCs and 6 particle-bound elements were calculated from personal concentrations and published cancer unit risks. RESULTS: The median cumulative risk from personal VOC exposures for this sample of NYC high school students was 666 per million and was greater than the risks from ambient exposures by a factor of about 5. In the LA sample, median cancer risks from VOC personal exposures were 486 per million, about a factor of 4 greater than ambient exposure risks. The VOCs with the highest cancer risk included 1,4-dichlorobenzene, formaldehyde, chloroform, acetaldehyde, and benzene. Of these, benzene had the greatest contributions from outdoor sources. All others had high contributions from indoor sources. The cumulative risks from personal exposures to the elements were an order of magnitude lower than cancer risks from VOC exposures. CONCLUSIONS: Most VOCs had median upper-bound lifetime cancer risks that exceeded the U.S. Environmental Protection Agency (EPA) benchmark of 1 x 10-6 and were generally greater than U.S. EPA modeled estimates, more so for compounds with predominant indoor sources. Chromium, nickel, and arsenic had median personal cancer risks above the U.S. EPA benchmark with exposures largely from outdoors and other microenvironments. The U.S. EPA-modeled concentrations tended to overestimate personal cancer risks for beryllium and chromium but underestimate risks for nickel and arsenic.     

Assessing total exposures to gasoline vapor using the source exposure model.

Recent developments in source apportionment modeling of volatile organic compounds (VOCs) include receptor modeling (RM) applications to "total" (indoor and outdoor) exposure assessment for source of VOC. Source fingerprints are available for major VOC sources such as gasoline vapor, automobile exhaust, refinery emissions, cleaning solvent vapors, printing inks, and waste-water treatment facilities. The relative proportion of each VOC species in the source fingerprint enables the RM method, through a least squares analysis, to identify each source's presence and quantify its contribution to ambient air concentrations. Sampling periods and locations may be selected to represent microenvironmental exposures. Receptor modeling has direct applicability to determining the relative contribution of gasoline vapors to VOC exposures in the general population.     

The Los Angeles TEAM Study: personal exposures, indoor-outdoor air concentrations, and breath concentrations of 25 volatile organic compounds.

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.     

Unmetabolized VOCs in urine as biomarkers of low level exposure in indoor environments

This study aimed to test the possible use of unmetabolized volatile organic compounds (VOCs) in urine as biomarkers of low-level indoor environmental exposure. Twenty-four subjects in 13 dwellings in a prefecture of Japan participated in this study. Air samples of the breathing zone were collected in the living room and bedroom, along with spot urine samples (before bedtime and first morning voids). Toluene, ethylbenzene, xylene isomers, styrene and p-dichlorobenzene in the air and urine samples were measured by gas chromatography/mass spectrometry. For the 21 subjects without solvent exposure at work, there were significant correlations between the time-weighted average air concentrations in the bedroom and morning urinary concentrations for toluene, o-xylene, total xylene and p-dichlorobenzene (correlation coefficients of 0.54, 0.61, 0.56 and 0.84, respectively). Multiple linear regression analysis showed only air VOCs in the bedroom influenced the morning urinary VOC concentrations. We concluded that unmetabolized VOCs in the urine can provide a reliable biological indicator for air VOC exposures in non-occupational environments.     

Risk assessment of exposure to volatile organic compounds in different indoor environments

The lifetime cancer risks of exposure of cooks and food service workers, office workers, housewives, and schoolchildren in Hong Kong to volatile organic compounds (VOCs) in their respective indoor premises during normal indoor activities were assessed. The estimated cancer risk for housewives was the highest, and the second-highest lifetime cancer risk to VOC exposure was for the groups of food service and office workers. Within a certain group of the population, the lifetime cancer risk of the home living room was one to two orders of magnitude higher than that in other indoor environments. The estimated lifetime risks of food service workers were about two times that of office workers. Furthermore, the cancer risks of working in kitchen environments were approximately two times higher than the risks arising from studying in air-conditioned classrooms. The bus riders had higher average lifetime cancer risks than those travelling by Mass Transit Railway. For all target groups of people, the findings of this study show that the exposures to VOCs may lead to lifetime risks higher than 1 x 10(-6). Seven indoor environments were selected for the measurement of human exposure and the estimation of the corresponding lifetime cancer risks. The lifetime risks with 8-h average daily exposures to individual VOCs in individual environments were compared. People in a smoking home had the highest cancer risk, while students in an air-conditioned classroom had the lowest risk of cancer. Benzene accounted for about or more than 40% of the lifetime cancer risks for each category of indoor environment. Nonsmoking and smoking residences in Hong Kong had cancer risks associated with 8-h exposures of benzene above 1.8 x 10(-5) and 8.0 x 10(-5), respectively. The cancer risks associated with 1,1-dichloroethene, chloroform, methylene chloride, trichloroethene, and tetrachloroethene became more significant at selected homes and restaurants. Higher lifetime cancer risks due to exposure to styrene were only observed in the administrative and printing offices and air-conditioned classrooms. Higher lifetime cancer risks related to chloroform exposures were observed at the restaurant and the canteen.     

Evaporative gasoline emissions and asthma symptoms

Attached garages are known to be associated with indoor air volatile organic compounds (VOCs). This study looked at indoor exposure to VOCs presumably from evaporative emissions of gasoline. Alaskan gasoline contains 5% benzene making benzene a marker for gasoline exposure. A survey of randomly chosen houses with attached garages was done in Anchorage Alaska to determine the exposure and assess respiratory health. Householders were asked to complete a health survey for each person and a household survey. They monitored indoor air in their primary living space for benzene, toluene, ethylbenzene and xylenes for one week using passive organic vapor monitoring badges. Benzene levels in homes ranged from undetectable to 58 parts per billion. The median benzene level in 509 homes tested was 2.96 ppb. Elevated benzene levels in the home were strongly associated with small engines and gasoline stored in the garage. High concentrations of benzene in gasoline increase indoor air levels of benzene in residences with attached garages exposing people to benzene at levels above ATSDR's minimal risk level. Residents reported more severe symptoms of asthma in the homes with high gasoline exposure (16%) where benzene levels exceeded the 9 ppb.