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Volatile organic compounds (VOCs) represent a broad class of chemicals, many of which can be found in indoor air including residential indoor air. VOCs derive from a variety of sources including cleaning products, cooking practices, fragrances and fresheners, hobbies and at-home work behaviors. This study examined residential indoor air in homes (n = 99) in southeast Louisiana using passive organic vapor monitors and gas chromatography/mass spectrometry to determine if select VOCs were present, at what concentrations, and if those posed any potential long-term health risks. Twenty-nine VOCs were targeted in cross-sectional analyses using a 48-h sampling period. Twelve VOCs were detected in most of the homes sampled including xylenes, pinenes, benzene, toluene, ethylbenzene, hexane, pentane, chloroform, and carbon tetrachloride. Concentrations of alkanes and BTEX compounds were highly correlated (Spearman's r > 0.63, p < 0.0001). Using health risk measures (i.e. reference concentrations [RfCs] and inhalation unit risks [IURs]) available from the USEPA non-cancer risk assessments and cancer risk assessments were developed for some of these VOCs. Alkanes and BTEX compounds likely come from the same indoor source(s). Using existing health standards published by the USEPA, no unacceptable non-cancer risks were evident except under extremely high concentrations. Lifetime cancer risks, on the other hand, may well be considered unacceptable for chloroform and benzene (upper IUR) and for the combination of chloroform, benzene, and carbon tetrachloride. These exceeded a 1 in 10,000 cancer risk threshold in 35–50% of our simulations. Further study of residential indoor air in low-income women's homes in this area is needed. Including a larger number of VOCs may reveal yet more potential health risks. [ABSTRACT FROM AUTHOR]

Traffic-related air and noise pollution on or near major roadways have been examined but these pollutants have not been extensively investigated away from major roadways in residential communities, especially in the United States. To evaluate the impact of trucks and trains passing nearby on air and noise pollution in residential areas during non-rush hours, we simultaneously measured concentrations of size-resolved airborne particulate matter (PM) and sound pressure levels as A-weighted equivalent (dBA) with frequencies in three underserved communities adjacent to industrial facilities in Houston, TX. We found that median concentrations for PM 1 (particle size ≤ 1 µm) and PM 10 (particle size ≤ 10 µm) were highest when trucks passed by at sampling locations, followed by periods when trains passed by. PM 1 and PM 10 concentrations were lowest at background (defined when there was no truck or train traffic near the monitoring location). Median PM 2.5 (particle size ≤ 2.5 µm) mass concentrations were 19.8 µg/m 3 (trains), 16.5 µg/m 3 (trucks), and 13.9 µg/m 3 (background). Short-term increases in noise were attributed to trains and trucks passing nearby as well. The median noise levels were the highest when trains passed by (66.7 dBA) followed by periods when trucks were in the vicinity of the monitoring locations (62.5 dBA); background levels were 58.2 dBA. The overall Spearman correlation coefficients between air and noise pollution were between 0.09 and 0.46. Hence, we recommend that both air pollutant and noise levels be concurrently evaluated for accurate exposure assessment related to traffic sources in residential communities. [ABSTRACT FROM AUTHOR]

Exposure to ambient particulate matter (PM) is known as a significant risk factor for mortality and morbidity due to cardiorespiratory causes. Owing to increased interest in assessing personal and community exposures to PM, we evaluated the feasibility of employing a low-cost portable direct-reading instrument for measurement of ambient air PM exposure. A Dylos DC 1700 PM sensor was collocated with a Grimm 11-R in an urban residential area of Houston Texas. The 1-min averages of particle number concentrations for sizes between 0.5 and 2.5 µm (small size) and sizes larger than 2.5 µm (large size) from a DC 1700 were compared with the 1-min averages of PM2.5(aerodynamic size less than 2.5 µm) and coarse PM (aerodynamic size between 2.5 and 10 µm) concentrations from a Grimm 11-R. We used a linear regression equation to convert DC 1700 number concentrations to mass concentrations, utilizing measurements from the Grimm 11-R. The estimated average DC 1700 PM2.5concentration (13.2 ± 13.7 µg/m3) was similar to the average measured Grimm 11-R PM2.5concentration (11.3 ± 15.1 µg/m3). The overall correlation (r2) for PM2.5between the DC 1700 and Grimm 11-R was 0.778. The estimated average coarse PM concentration from the DC 1700 (5.6 ± 12.1 µg/m3) was also similar to that measured with the Grimm 11-R (4.8 ± 16.5 µg/m3) with anr2of 0.481. The effects of relative humidity and particle size on the association between the DC 1700 and the Grimm 11-R results were also examined. The calculated PM mass concentrations from the DC 1700 were close to those measured with the Grimm 11-R when relative humidity was less than 60% for both PM2.5and coarse PM. Particle size distribution was more important for the association of coarse PM between the DC 1700 and Grimm 11-R than it was for PM2.5. Implications: The performance of a low-cost particulate matter (PM) sensor was evaluated in an urban residential area. Both PM2.5and coarse PM (PM10-2.5) mass concentrations were estimated using a DC1700 PM sensor. The calculated PM mass concentrations from the number concentrations of DC 1700 were close to those measured with the Grimm 11-R when relative humidity was less than 60% for both PM2.5and coarse PM. Particle size distribution was more important for the association of coarse PM between the DC 1700 and Grimm 11-R than it was for PM2.5. [ABSTRACT FROM AUTHOR]

Concentrations of volatile organic compounds (VOCs) measured outside homes in Houston, TX and Los Angeles, CA were characterized by the effects of source proximity and meteorological factors. Benzene, toluene, ethylbenzene, m , p -xylene, o -xylene (BTEX), methyl tert butyl ether (MTBE), tetrachloroethylene (perchloroethylene, PCE), and carbon tetrachloride (CCl 4 ) were examined. Multiple stepwise regression analysis converged the best-fit models with predictors from meteorological conditions and the proximity to specific point, area, and mobile sources on the residential outdoor VOC concentrations. Negative associations of wind speed with concentrations demonstrated the effect of dilution by high wind speed. Atmospheric stability increase was associated with concentration increase. Petrochemical source proximity was a significant predictor for BTEX and MTBE concentrations in Houston. Ethylbenzene and xylene source proximity was a significant predictor in Los Angeles. Close proximity to area sources such as scrap metal recycling or dry cleaning facilities increased the MTBE, PCE, and CCl 4 concentrations in Houston and Los Angeles. Models for ethylbenzene, m , p -xylene, and MTBE in Houston, and benzene in Los Angeles explained that for the median values of the meteorological factors, homes closest to influential highways would have concentrations that were 1.7–2.2 fold higher than those furthest from these mobile emission sources. If the median distance to sources were used in the models, the VOC concentrations varied 1.7 to 6.6 fold as the meteorological conditions varied over the observed range. These results highlight that each urban area is unique and localized sources need to be carefully evaluated to understand potential contributions to VOC air concentrations near residences, which influence baseline indoor air concentrations and personal exposures. Results of this study could assist in the appropriate design of monitoring networks for community-level sampling. They may also improve the accuracy of exposure models linking emission sources with estimated pollutant concentrations at the residential level. [ABSTRACT FROM AUTHOR]