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Measurement of gaseous PAHs with an innovative passive sampler in community exposure studies
Citation:
Zhihua, T., P. Lioy, H. A. OZKAYNAK, M. M. JOHNSON, AND R. Edward. Measurement of gaseous PAHs with an innovative passive sampler in community exposure studies. Presented at International Society for Environmental Epidemiology Annual Conference, Pasadena, CA, October 12 - 14, 2008.
Impact/Purpose:
research results
Description:
A sensitive, simple, and cost-effective passive sampling methodology was developed to quantify gaseous polycyclic aromatic hydrocarbons (PAHs) in personal, indoor and outdoor air. A Fan-Lioy passive PAH sampler (FL-PPS) is constructed from four 80 sections of 1 cm long SPB-5 GC columns (0.75-mm ID and 7-µm film thickness). Each section is covered with a stainless steel mesh (50 × 50 mesh size) and housed in the center of a 1.5 cm long stainless steel tube, similar to a mini-honeycomb denuder. Given the unique feature of the GC column stationary phase, gaseous PAHs are collected on the inner surfaces of the columns by molecular diffusion and can be either thermally desorbed or liquid extracted during subsequent analysis by GC/MS. Laboratory tests were conducted to evaluate the performance of the sampler for the measurement of naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, and pyrene for a range of face velocity, temperature, relative humidity, and PAH concentration. Except naphthalene, the sampling rate was stable for the 7 PAHs over a sampling duration of 8-48 hours. The sampling rate for naphthalene was stable for a sampling period of 8 hours but decreased along with increase of sampling time and reached saturation at 24 hours. The effects of other parameters on the sampling rate were not significant for all the compounds tested, indicating that the sampler can be used to measure gaseous PAHs in different microenvironments. Further evaluation was performed in two community exposure studies conducted in two locations with different environmental conditions, Detroit, MI vs. Meseta Purepecha region, Mexico. The sampler was used to measure indoor and outdoor gaseous PAHs in 46 asthma homes in Detroit and personal and indoor PAHs for 42 participants in Mexico. During the Detroit study, the sampler was deployed by subject and all samplers were recovered at the end of the study. Among the 195 samples, there were only 7% invalid samples and 7% suspicious samples due to incompliance with the sampling protocols. In the Mexico study, only 1 sampler was lost. The average recovery of PAH from both studies ranged from 61-89% and the method precision (CV%) ranged from 30-51%. Results showed that PAH concentrations were 5-40 times higher in Mexico than in Detroit, varied by species, but naphthalene was underestimated in Mexico due to potential saturation of the sampler. In summary, the FL-PPS is suitable for trace level PAH measurement in community exposure studies, and a sampling duration of 24 hours or longer is recommended for a better detection of most gaseous PAHs in community settings. The sampler is small and light weight, and can be worn by small children during an exposure study. Operation of the device is simple and can be handled by participant. The 8 PAHs tested are stable on the samplers for ~8 months stored at 4ºC. The sampler is a cost-effective device and can be reused for at least 10 times after a simple baking process. Improvement is needed to reduce the background of the sampler. Although this work was reviewed by EPA and approved for publication, it may not y reflect official Agency policy.