TEMPORAL VARIABILITY OF BENZENE EXPOSURES FOR RESIDENTS IN SEVERAL NEW-JERSEY HOMES WITH ATTACHED GARAGES OR TOBACCO-SMOKE

The U.S Environmental Protection Agency's (EPA) previous TEAM studies of personal exposure to VOCs for 700 residents in several U.S. cities found that indoor air concentrations were often higher than outdoor le vels. Several potential sources of benzene exposure were identified, i ncluding environmental tobacco smoke and materials or activities assoc iated with attached garages. Indoor, personal, and outdoor monitoring was conducted at eleven New Jersey homes over multiple 12-hr monitorin g periods. One study objective was to assess the impact of attached ga rages on human exposure to benzene and the variability of benzene expo sure across time. Benzene was also measured in several homes inhabited by smokers and in homes without known combustion sources for comparat ive purposes. At homes with a garage or environmental tobacco smoke, m ean indoor and personal benzene concentrations were two to five times higher than outdoor levels at all but one home. Mean personal exposure s ranged from 8 to 31 mug/m3. Indoor/outdoor ratios were calculated an d ranged from 0.8 to 11. Benzene levels in the four garages ranged fro m 3 to 196 mug/m3 and usually were higher than either indoor living ar eas or personal levels. Multi-zone air exchange rates were measured, a nd benzene source strengths in each zone were estimated. Garage source strength estimates for benzene ranged from 310 to 52,000 mug/h. The m ass transfer of benzene from sources in the garage to home living area s was also large in three of the homes, ranging from 730 to 26,000 mug /h. Materials or activities in the garage were a source of benzene exp osure for the residents in these three homes. Large temporal variation s (factors of 2 to 30) were observed in indoor and personal benzene co ncentrations, indoor/outdoor ratios, and source strengths over the six or ten monitoring periods at each home. Changes in outdoor air benzen e levels were an underlying factor in changing exposure levels, with i ndoor sources further elevating indoor air levels and personal exposur es.