Measured Indoor Concentrations Research Articles

Indoor fine particulate matter and stove-use characteristics in homes heated by wood stoves: results from control homes in the KidsAIR randomized trial

Background/Aim: Household heating using wood stoves is common practice in many rural areas of the United States (US) and can lead to high concentrations of indoor fine particulate matter (PM2.5); yet there is limited research on household and behavioral factors that contribute to PM2.5 levels in such homes. Our aims were to characterize PM2.5 concentrations, evaluate household and stove-use characteristics that impact PM2.5, and assess the feasibility of interventions to lower PM2.5 in rural US homes that used wood stoves for heating.Methods: KidsAIR was a three-arm post-only randomized trial in wood stove households from three study areas. We measured indoor concentrations of PM2.5 over a 6-day sampling period during the winter and assessed household and stove-use characteristics. As the two intervention arms (education and air-filtration) were designed to impact PM2.5 concentrations, we focused these analyses on homes in the control arm (no intervention, n=93).Results: In preliminary analyses, the mean indoor PM2.5 concentration across all control homes was 28 µg/m3 (standard deviation [sd]=68), with higher concentrations in Alaska sites (47 µg/m3, sd=95, n=10) than Navajo Nation (NN) or Montana sites (29 µg/m3, sd=76, n=23; 25 µg/m3, sd=59, n=60). Stoves were often over 5 years old (54%) and of poor quality. More participants in NN (35%) reported heavy burning during PM2.5 measurement than Alaska (10%) or Montana (12%), and more participants in Alaska (70%) and NN (83%) burned wood <3 months after collection than in Montana (25%). Mean wood moisture content was lower in NN (6%) than Alaska (14%) and Montana (13%).Conclusions: We observed poor stove quality, inconsistent burn practices, and moderately high PM2.5 concentrations inside rural US homes that heated with wood stoves. Our findings highlight the need for, and the complex nature of, culturally- and regionally-appropriate interventions to reduce indoor air pollution in rural wood-burning homes.

Vertical variation and source evaluation of VOCs and inorganic pollutants in a university building

Concentrations of volatile organic compounds (VOCs) and inorganic pollutants including sulfur dioxide (SO2), nitrogen dioxide (NO2), and ozone (O3) were measured using passive samplers in both indoor and outdoor environments at 2, 5, 8, 13, 17, 24, and 29 m from the ground level at a high-rise building in the Middle East Technical University campus in Ankara, Turkey. The measured indoor concentrations of ∑24VOCs were highly variable, ranging from 98 μg m−3 (at the ground floor) to 235.3 μg m−3 (at the fourth floor), while the outdoor concentrations varied between 96.8 μg m−3 (at the seventh floor) and 189.8 μg m−3 (at the ground level). Outdoor concentrations of inorganic pollutants ranged between 58 μg m−3 at the ground floor and 26 μg m−3 at the ninth floor for SO2, and 59.9 μg m−3 at the ground floor and 31.2 μg m−3 at the ninth floor for NO2. A similar decreasing trend with altitude was also observed for indoor concentrations of these pollutants. Indoor and outdoor O3 concentrations did not change with altitude. Statistically significant correlations were found between indoor and outdoor concentrations of some of the measured NO2, SO2 toluene, octane, nonane and 1,2-dichlorobenzene, indicating moderate-to-strong relationships between their indoor and outdoor concentrations. The factor analysis revealed six factors for both indoor and outdoor data. Traffic was found to be the highest contributor to the measured VOCs, SO2, and NO2 concentrations, which was followed by painting activities.

Passive air sampling of flame retardants and plasticizers in Canadian homes using PDMS, XAD-coated PDMS and PUF samplers

Passive air samplers (PAS) were evaluated for measuring indoor concentrations of phthalates, novel brominated flame retardants (N-BFRs), polybrominated diphenyl ethers (PBDEs), and organophosphate esters (OPEs). Sampling rates were obtained from a 50-day calibration study for two newly introduced PAS, polydimethylsiloxane (PDMS) or silicone rubber PAS (one with and one without a coating of styrene divinyl benzene co-polymer, XAD) and the commonly used polyurethane foam (PUF) PAS. Average sampling rates normalized to PAS surface area were 1.5 ± 1.1 m3 day−1 dm−2 for both unsheltered PDMS and XAD-PDMS, and 0.90 m3 ± 0.6 day−1dm−2 for partially sheltered PUF. These values were derived based on the compound-specific sampling rates measured here and in the literature for the PAS tested, to reasonably account for site-specific variability of sampling rates.PDMS and PUF were co-deployed for three weeks in 51 homes located in Ottawa and Toronto, Canada. Duplicate PUF and PDMS samplers gave concentrations within 10% of each other. PDMS and PUF-derived air concentrations were not statistically different for gas-phase compounds. PUF had a higher detection of particle-phase compounds such as some OPEs. Phthalate and OPE air concentrations were ∼100 times higher than those of N-BFRs and PBDEs. Concentrations were not systematically related to PM10, temperature or relative humidity.We conclude that both PAS provide replicable estimates of indoor concentrations of these targeted semi-volatile organic compounds (SVOCs) over a three-week deployment period. However, PUF is advantageous for collecting a wider range of compounds including those in the particle phase.

Real-time indoor measurement of health and climate-relevant air pollution concentrations during a carbon-finance-approved cookstove intervention in rural India

Biomass combustion in residential cookstoves is a major source of air pollution and a large contributor to the global burden of disease. Carbon financing offers a potential funding source for health-relevant energy technologies in low-income countries. We conducted a randomized intervention study to evaluate air pollution impacts of a carbon-finance-approved cookstove in rural South India. Prior research on this topic often has used time-integrated measures of indoor air quality. Here, we employed real-time monitors (∼24 h measurement at ∼ minute temporal resolution), thereby allowing investigation of minutely and hourly temporal patterns. We measured indoor concentrations of fine particulate matter (PM2.5), black carbon (BC) and carbon monoxide (CO) in intervention households (used newer, rocket-type stoves) and control households (“nonintervention”; continued using traditional open fire stoves). Some intervention households elected not to use only the new, intervention stoves (i.e., elected not to follow the study-design protocol); we therefore conducted analysis for “per protocol” versus “intent to treat.” We compared 24 h averages of air pollutants versus cooking hours only averages. Implementation of the per protocol intervention cookstove decreased median concentrations of CO (by 1.5 ppm (2.8 − 1.3; control − per protocol), p = 0.28) and PM2.5 (by 148 μg/m3 (365 − 217), p = 0.46) but increased BC concentration (by 39 μg/m3 (26 − −12), p < 0.05) and the ratio of BC/PM2.5 (by 0.25 (−0.28 − −0.03), p < 0.05) during cooking-relevant hours-of-day relative to controls. Calculated median effective air exchange rates based on decay in CO concentrations were stable between seasons (season 1: 2.5 h−1, season 2: 2.8 h−1). Finally, we discuss an analytical framework for evaluating real-time indoor datasets with limited sample sizes. For the present study, use of real-time (versus time-averaged) equipment substantially reduced the number of households we were able to monitor.

高齢者施設における室内環境と健康性に関する調査 （第９報）寒冷地における二酸化炭素濃度を用いた加湿の分析

高齢者施設における室内環境と健康性に関する調査 （第９報）寒冷地における二酸化炭素濃度を用いた加湿の分析

Volatile organic compounds and particulate matter in child care facilities in the District of Columbia: Results from a pilot study

BackgroundMany young children in the U.S. spend a significant portion of their day in child care facilities where they may be exposed to contaminants linked to adverse health effects. Exposure data on volatile organic compounds (VOCs) and particulate matter (PM) in these settings is scarce. ObjectiveTo guide the design of a larger exposure assessment study in urban child care facilities, we conducted a pilot study in which we characterized indoor concentrations of select VOCs and PM. MethodsWe recruited 14 child care facilities in the District of Columbia (Washington, DC) and measured indoor concentrations of seven VOCs (n=35 total samples; 2–5 samples per facility): benzene, carbon tetrachloride, chloroform, ethylbenzene, o-xylene, p-xylene, and toluene in all facilities; and collected real-time PM measurements in seven facilities. We calculated descriptive statistics for contaminant concentrations and computed intraclass correlation coefficients (ICC) to evaluate the variability of VOC levels indoors. We also administered a survey to collect general health information on the children attending these facilities, and information on general housekeeping practices and proximity of facilities to potential sources of target contaminants. ResultsWe detected six of the seven VOCs in the majority of child care facilities with detection frequencies ranging from 71% to 100%. Chloroform and toluene were detected in all samples. Median (range) concentrations for toluene, chloroform, benzene, o-xylene, ethylbenzene, and carbon tetrachloride were: 5.6µg/m3 (0.6–16.5µg/m3), 2.8µg/m3 (0.4–53.0µg/m3), 1.4µg/m3 (below the limit of detection or <LOD – 4.4µg/m3), 1.1µg/m3 (<LOD – 35.7µg/m3), 1.0µg/m3 (<LOD – 28.5µg/m3), and 1.0µg/m3 (<LOD – 1.6µg/m3), respectively. The ICCs for the VOCs measured ranged from 0.32 to 0.75. Child care facility median concentrations for PM2.5 and PM10 were 20.1µg/m3 and 26.3µg/m3, respectively. Chlorine bleach, a source of chloroform, was used in almost all facilities, air fresheners and/or scented candles were used in half of the facilities, and at least one child in each facility had physician-diagnosed asthma (median asthma prevalence rate=10.2%). ConclusionWe found quantifiable levels of VOCs and PM in the child care facilities sampled. Given that exposures to environmental contaminants during critical developmental stages may have long lasting impacts on children's health, larger studies are needed to characterize and identify sources of exposures to these and other indoor contaminants to develop exposure mitigation strategies.

Indoor environmental quality in French dwellings and building characteristics

Abstract A national survey on indoor environmental quality covering 567 residences in mainland France was performed during 2003–2005. The measured parameters were temperature, relative humidity, CO 2 , and the indoor air pollutants: fourteen individual volatile organic compounds (VOC), four aldehydes and particulate matter PM 10 and PM 2.5. The measured indoor concentrations were analyzed for correlations with the building characteristics: type of dwelling, period of construction, dwelling location, type of ventilation system, building material, attached garage and retrofitting. The median night time air exchange rate (AER) for all dwellings was 0.44 h −1 . The night time AER was higher in apartments (median = 0.49 h −1 ) than in single-family houses (median = 0.41 h −1 ). Concentration of formaldehyde was approximately 30% higher in dwellings built after 1990 compared with older ones; it was higher in dwellings with mechanical ventilation and in concrete buildings. The VOC concentrations depended on the building characteristics to various extents. The sampling season influenced the majority of the indoor climate parameters and the concentrations of the air pollutants to a higher degree than the building characteristics. Multivariate linear regression models revealed that the indoor–outdoor difference in specific humidity, a proxy for number of occupants and their indoor activities, remained a significant predictor for most gaseous and particulate air pollutants. The other strong predictors were outdoor concentration, smoking, attached garage and AER (in descending order).

Indoor Exposure to Particulate Matter and Age at First Acute Lower Respiratory Infection in a Low-Income Urban Community in Bangladesh

The timing of a child's first acute lower respiratory infection (ALRI) is important, because the younger a child is when he or she experiences ALRI, the greater the risk of death. Indoor exposure to particulate matter less than or equal to 2.5 µm in diameter (PM2.5) has been associated with increased frequency of ALRI, but little is known about how it may affect the timing of a child's first ALRI. In this study, we aimed to estimate the association between a child's age at first ALRI and indoor exposure to PM2.5 in a low-income community in Dhaka, Bangladesh. We followed 257 children from birth through age 2 years to record their age at first ALRI. Between May 2009 and April 2010, we also measured indoor concentrations of PM2.5 in children's homes. We used generalized gamma distribution models to estimate the relative age at first ALRI associated with the mean number of hours in which PM2.5 concentrations exceeded 100 µg/m(3). Each hour in which PM2.5 levels exceeded 100 µg/m(3) was independently associated with a 12% decrease (95% confidence interval: 2, 21; P = 0.021) in age at first ALRI. Interventions to reduce indoor exposure to PM2.5 could increase the ages at which children experience their first ALRI in this urban community.

Population inhalation exposure to polycyclic aromatic hydrocarbons and associated lung cancer risk in Beijing region: Contributions of indoor and outdoor sources and exposures

Polycyclic aromatic hydrocarbons (PAHs) are among the most toxic air pollutants in China. Efforts in assessing population inhalation exposure to PAHs, and its contribution to lung cancer risk for Chinese residents, have been limited due to insufficient data on measured indoor concentrations. A mass-balance model to predict indoor PAH concentrations was developed, along with estimated exposures and attributable lung cancer risks for residents in the Beijing region in 2006, with a 2-stage Monte Carlo simulation framework. The exposures and risks were split into three parts, based on the sources and places of exposure, to estimate the contributions of indoor and outdoor PAH sources and exposures, in order to better understand the source and place pattern of PAH exposure. PAHs bring considerable lung cancer risk to the population of Beijing region. The population attributable fraction (PAF) of lung cancer for Beijing's overall population is 2.99% [95% confidence interval (CI): 1.71%–4.26%]. Median contribution of indoor exposure to outdoor-originated PAHs (OUT–in) is 78% (CI: 73%–81%) in the overall population, for 97% (CI: 94%–99%) of whom OUT–in is the largest contributor. Rural residents are facing considerable exposure to indoor-originated PAHs (IN–in), which dominates the total exposure in 12% (CI: 2%–24%) of the rural population. This model framework could be used in quantitative comparison of different interventions on exposure to PAHs as well as other airborne pollutants.

Airborne particulate matter and gaseous air pollutants in residential structures in Lodi province, Italy

The province of Lodi is located in northern Italy on the Po River plain, where high background levels of air pollutants are prevalent. Lodi province is characterized by intensive agriculture, notably animal husbandry. This paper assesses indoor levels of selected airborne pollutants in 60 homes in the province, with special attention to size-fractionated particulate matter (PM). Indoor PM₂.₅ concentrations are frequently higher than current guidelines. PM₁₀ and nitrogen dioxide also exceed the respective guideline recommendations in some cases, noting that 24-h nitrogen dioxide levels were compared with an annual limit value. All other studied pollutant levels are below current international guidelines. Among indoor PM size fractions, PM₀.₅ is predominant in terms of mass concentrations corresponding to 57% of PM₁₀ in summer and 71% in winter. A strong seasonal trend is observed for all studied pollutants, with higher levels in winter corresponding to changes in ambient concentrations. The seasonal variation in PM₁₀ is largely due to PM₀.₅ increase from summer to winter. Summer indoor PM levels are mainly from indoor-generated particles, while particles of outdoor origin represent the main contribution to winter indoor PM levels. On average, indoor concentrations of coarse PM are mostly constituted by indoor-generated particles. This study presents a comparison between measured indoor concentrations in the study area and indoor air quality guideline criteria. Accordingly, particulate matter (PM) and NO₂ are identified as key pollutants that may pose health concerns. It is also found that indoor PM in residential units is mainly constituted by particles with aerodynamic diameters <0.5 μm, especially in winter. Risk mitigation strategies should be focused on the reduction in indoor levels of NO₂ and ultrafine and fine particles, both infiltrated from outdoors and generated by indoor sources.

Screening of formaldehyde indoor sources and quantification of their emission using a passive sampler

The formaldehyde emission rates from building and furniture materials in 24 student rooms were measured using a passive sampling method parallel to a monitoring of indoor and outdoor concentrations. This passive tool represents an interesting alternative to standard dynamic methods as it is easier to implement for field investigation. Although the indoor formaldehyde concentrations (21.3 μg m −3 on average) are at a medium level, consistent with earlier published results, the recorded emission rates are globally low (from 1 to 15 μg m −2 h −1) except for the high emission of beds identified in one building (87.3 μg m −2 h −1 on average). Data analysis revealed that the emissions released from furniture and building materials are the main contributions to the indoor formaldehyde concentrations with 45 and 43% on average. The high formaldehyde levels in rooms are mainly explained by the rise of formaldehyde emissions from indoor materials with temperature although the buildings and the furniture were older than 7 years. Basing on the data of emission rates, outdoor concentrations and air exchange rates, a one compartment mass balance model was used to calculate indoor concentrations. A good agreement was found between the predictions of the model and the measured indoor concentrations. This methodology could lead to the definition of arrangements for the efficient reduction of indoor formaldehyde levels.

HVAC air-quality model and its use to test a PM 2.5 control strategy

This paper presents a MATLAB ® Simulink air-quality model of a commercial building with a heating, ventilation, and air conditioning (HVAC) system in Fairbanks, Alaska. Outdoor and indoor real-time fine particulate matter (PM 2.5) levels were measured at this building during a summer wild-fire smoke episode and then during a winter period. The correlation coefficient between the model-predicted and the measured indoor concentrations was 0.99 for the summer and 0.98 for the winter, justifying the usability of the model for further studies. An HVAC control algorithm was developed that reduces the indoor PM 2.5 levels. The algorithm was tested using the HVAC Simulink model and the outdoor PM 2.5 data from the summer smoke episode. The average indoor PM 2.5 level with this control algorithm was 65% lower than with the regular control. Thanks to the PM 2.5 control strategy being automatically engaged only during episodes, it was shown to have the potential of significantly reducing the indoor PM 2.5 levels without significantly compromising the purpose of the original control strategy.

Estimating contributions of indoor and outdoor sources to indoor carbonyl concentrations in three urban areas of the United States

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.

Prescribed Burns and Wildfires in Colorado: Impacts of Mitigation Measures on Indoor Air Particulate Matter

Wildfires and prescribed burns are receiving increasing attention as sources of fine particulate matter (PM2.5). The goal of this research project was to understand the impact of mitigation strategies for residences impacted by scheduled prescribed burns and wildfires. Pairs of residences were solicited to have PM2.5 concentrations monitored inside and outside of their houses during four fires. The effect of using air cleaners on indoor PM2.5 was investigated, as well as the effect of keeping windows closed. Appropriately sized air cleaners were provided to one of each pair of residences; occupants of all of the residences were asked to keep windows shut and minimize opening of exterior doors. Additionally, residents were asked to record all of the activities that may be a source of particulate matter, such as cooking and cleaning. Measurements were made during one prescribed burn and three wildfires during the 2002 fire season. Outdoor 24‐hr average PM2.5 concentrations ranging from 6 to 38 µg/m3 were measured during the fires, compared with levels of 2–5 µg/m3 during background measurements when no fires were burning. During the fires, PM2.5 was <3 µg/m3 inside all of the houses with air cleaners installed. This corresponds with a decrease of 63–88% in homes with the air cleaners operating when compared with homes without air cleaners. In the homes without the air cleaners, measured indoor concentrations were 58–100% of the concentrations measured outdoors.

Carcinogen specific dosimetry model for passive smokers of various ages

Studies indicate that being exposed to second hand smoke increases the chance of developing lung cancer. Understanding the deposition of carcinogenic particles present in second hand smoke is necessary to understand the development of specific histologic type cancers. In this study, a deposition model is presented for subjects of various ages exposed to sidestream smoke. The model included particle dynamics of coagulation, hygroscopic growth, charge and cloud behavior. Concentrations were varied from the maximum measured indoor concentrations (10 6 particles/cm 3) to what would be expected from wisps of smoke (10 8 particles/cm 3). Model results agreed well with experimental data taken from human subject deposition measurements (four studies). The model results were used to determine the dose intensity (dose per unit airway surface area) of Benzo[ a]pyrene (BaP) in the respiratory tract for subjects of various ages. Model predictions for BaP surface concentration on the airway walls paralleled incident rates of tumors by location in the upper tracheobronchial region. Mass deposition efficiency was found to be larger for younger subjects, consistent with diffusion being the predominant mechanism for this particle size range. However, the actual dose intensity of BaP was found to be smaller for children than adults. This occurred due to the predominant effect of the smaller initial inhaled mass for children resulting from smaller tidal volumes. The resulting model is a useful tool to predict carcinogen specific particle deposition.

2000年全国実態調査に基づく住宅室内空気のVOC汚染の状況

The purpose of this research is to know the present status of the indoor air VOC pollution in Japanese houses. From the measured indoor concentrations and the questionnaire results from five thousand householders, the following results were obtained. 1. In 12.3% of the houses, the concentrations of toluene exceeded the guideline established by the Ministry of Health, Labor and Welfare of Japanese Government. And those of xylene and ethyl-benzene were 0.13% and 0%. 2. The concentrations in houses with ventilation systems were the same as those in houses without ventilation systems. 3. The structure types, the number of floors and the regions are considered as the main factors of concentrations.

An empirical model to predict indoor NO 2 concentrations

This paper discusses the development of an empirical model to predict indoor NO 2 concentration ( C in) from outdoor NO 2 concentration ( C out) measured just outside the homes. Concentrations were 48-h time integrated averages. Data from a study carried out on measurement of indoor, outdoor and personal exposure to nitrogen dioxide (NO 2) in Mumbai were used in the development of the model. Concentrations were measured over 2-day periods both in winter (February 1996) and summer (April 1996) for 43 respondents. The form of the developed model is C ̄ in =k C ̄ out +S/Q, where k, the ventilation factor and S/ Q the source term are the model constants. Analysis of variance and regression analysis indicated that type of fuel was the most significant factor influencing indoor concentration and model constants. Measured indoor concentrations were regressed on outdoor concentrations to evaluate model constants for kerosene and liquefied petroleum gas (LPG), which are the most predominantly used cooking fuels in Indian households. Final models, after evaluating the constants suggested that contribution to indoor NO 2 concentration due to indoor sources was higher in kerosene using households whereas in the case of LPG using households, the contribution due to outdoor sources was relatively higher. Results of model validation indicated that the predictive power of the models was good.

Pilot study of personal, indoor and outdoor exposure to benzene, formaldehyde and acetaldehyde

There is a lack of data for health risk assessment of long term personal exposure to certain ubiquitous air pollutants present particularly in urban atmospheres. The relationship between ambient background concentrations and personal exposure is often unknown. A pilot campaign to measure indoor concentrations, outdoor concentrations and personal exposure to benzene, formaldehyde and acetaldehyde was conducted in a medium sized French town. A strong contribution to total personal exposure was observed from indoor sources, especially for formaldehyde and acetaldehyde, suggesting that indoor sources are dominant for these compounds. For benzene, the average personal exposure exceeded a 10 microgm(-3) limit value, although this was not the case for the ambient background concentration. For formaldehyde, the limit level was also exceeded. Observations suggest that true personal exposure cannot be determined directly from measurements pertaining from fixed ambient background monitoring stations. It is hoped that this will be taken into consideration by the bodies responsible for monitoring air pollution and the future European Air Quality Directive.

On the Reduction of Error in Alpha Track Detector Measurements of Indoor 222Rn

Small plastic chambers containing alpha track detectors are often used for measuring indoor concentrations of 222Rn. This paper reports an experimental assessment of sources of error in measurements made with alpha track detector-containing chambers. The results demonstrate the feasibility of a nondestructive test for the identification of alpha track detector-containing chambers that are packaged in a way that does not effectively prevent ambient 222Rn from inducing tracks prior to field exposure. Results also indicate that there is statistically significant variation among manufacturing lots and among chemical processing batches. Error from these sources can be avoided or compensated if appropriate control measures are implemented as part of a quality assurance program during any survey using alpha track detector-containing chambers.

A Pilot Study to Measure Indoor Concentrations and Emission Rates of Polycyclic Aromatic Hydrocarbons

Sampling and analytical methods for gas- and particulate-phase polycylic aromatic hydrocarbons (PAH) in indoor air were evaluated in a controlled field study. Using 12-h, 25-m3 samples, gas-phase PAH were collected on XAD-4 resin and analyzed by GC-MS, and particulate-phase PAH were collected in filters and analyzed for by HPLC with fluorescence detection. Tests were conducted in homes and office buildings without active combustion sources and with gas stoves, wood stoves and cigarette smoking as controlled sources. Indoor concentrations, outdoor concentrations and air-exchange rates were simultaneously measured. The precisions of the concentrations were evaluated using collocated sample pairs collected indoors and outdoors. Net emission rates were calculated for the gas-phase PAH. Net emissions of these compounds were measured in buildings without active combustion sources. Environmental tobacco smoke was identified as a significant source of both gas- and particulate-phase PAH.