Levels and sources of personal inhalation exposure to volatile organic compounds.

Personal exposures to VOCs of 12 urban dwellers were measured directly via personal monitoring and indirectly via static monitoring combined with personal activity diaries. Over 5-10 days, day-to-day variations in personal exposures of individuals were substantial, with statistically significant (p<0.05) deviation from the normal distribution observed for daily exposures to one or more VOCs for several subjects. Daytime concentrations generally exceeded night time, with day:night mean concentration ratios for each sampling day >1 for most VOCs, with the maximum (3.85) occurring for 1,3-butadiene. Exposure in the home contributed 50-80% of overall individual exposure to 1,3-butadiene and benzene. For most VOCs, while absolute values of direct and indirect exposure estimates were significantly different (p<0.05), linear regression of direct and indirect exposure estimates revealed statistically significant correlation (p<0.01), confirming previous observations that indirect monitoring can provide satisfactory estimates of personal inhalation exposure to VOCs. ETS, the use of vehicles, and heating (but not cooking) all made appreciable contributions to personal exposure to all target VOCs.