RISK FACTORS FOR INCREASED BTEX PERSONAL EXPOSURE IN FOUR AUSTRALIAN CITIES.

Abstract

Elevated levels of volatile organic compounds (VOCS) have been reported in Australian cities, most typically associated with significant point sources, wood smoke impacted areas and heavily trafficked areas. The limited personal exposure monitoring of VOCs in Australia has focussed on specific high exposure groups such as commuters. As part of the commonwealth government's Living Cities program, a study was conducted to investigate the exposure of the urban population to four air toxics: benzene, toluene, ethylbenzene, xylene (BTEX). A cross sectional study of 207 non-smoking, non-occupationally exposed participants was undertaken in Perth, Sydney, Melbourne and Adelaide. Each participant wore a passive BTEX sampler over 24 hours for 5 consecutive days in winter and summer. Participants completed a diary for each day of monitoring and also completed a questionnaire. The range of daily BTEX concentrations for the study population were benzene (0.04–23.8ppb); toluene (0.03–2120ppb); ethylbenzene (0.03 −119ppb); and xylenes (0.04 −697ppb). The geometric mean BTEX exposures were 0.80; 2.83; 0.53; 2.35ppb respectively. A generalised linear model was used to investigate significant risk factors for increased BTEX exposure. There was no significant difference between winter and summer exposure measurements when the entire dataset was considered. Activities and locations found to significantly increase BTEX personal exposure included vehicle repair and machinery use; refuelling of motor vehicles, being in an enclosed carpark and time spent undertaking arts and crafts. Time spent outdoors was found to decrease personal exposure even though specific activities such as cycling/running and walking were found to increase exposure. A highly significant difference was found between the mean exposures observed in Perth compared with the other three States. This may largely be explained by differences in fuel composition and/or the differences in the density of motor vehicles in each city.