Research Triangle Institute, Research Triangle Park, NC, USA. Environmental Protection Agency, Cincinnati, OH, USA.

The project was designed to study indoor exposures to 30 chemicals representing a broad range of very volatile organic compounds (WOCs), volatile organic compounds (VOCs), and semi-volatile organic compounds (SOCs). Most of these chemicals will be considered by the California Air Resources Board for identification as toxic air contaminants. Indoor and outdoor samples were collected in 128 homes, and a total of 120 residents participated in personal monitoring. Information on residents' microenvironments also was collected. Common VOCs were found most often, and at the highest concentration, in indoor and personal air samples. WOCs and SOCs were less often found and usually at low concentrations for all air samples. For all of the common VOCs, personal air samples showed the highest concentrations followed by indoor air and then outdoor air samples. The study confirms previous observations that indoor levels of many VOCs are higher than outdoor levels. The indoor and personal concentrations from the study are very similar to those obtained in other northern California homes but lower than those from southern California homes. The findings from this and other related studies will improve the risk estimates of Californians' exposure to air pollution.

The primary purpose of the study was to obtain indoor and outdoor air concentration data for benzo(a)pyrene, other polynuclear aromatic hydrocarbons (PAHs), and phthalates in California residences to be used in making exposure predictions. To meet these objectives, a field monitoring study was performed in 125 homes in Riverside, California in the fall of 1990. In each home, two 12-hour indoor air samples were collected during daytime and overnight periods. In a subset of 65 homes, outdoor air samples were also collected. PAH and phthalate concentrations were measured in collected air samples using gas chromatography/mass spectrometry techniques. Along with field monitoring, information on potential source usage in the home was collected using questionnaires.