RÉSUMÉ
After reductions of fugitive and diffuse emissions by an industrial complex, a follow-up study was performed to determine the time variability of volatile organic compounds (VOCs) and the lifetime cancer risk (LCR). Passive samplers (3 M monitors) were placed outdoors (n = 179) and indoors (n = 75) in industrial, urban, and control areas for 4 weeks. Twenty-five compounds including n-alkanes, cycloalkanes, aromatics, chlorinated hydrocarbons, and terpenes were determined by GC/MS. The results show a significant decrease of all VOCs, especially in the industrial area and to a lesser extent in the urban area. The median outdoor concentration of benzene in the industrial area declined compared to the former study, around 85% and about 50% in the urban area, which in the past was strongly influenced by industrial emissions. Other carcinogenic compounds like styrene and tetrachloroethylene were reduced to approximately 60%. VOC concentrations in control areas remained nearly unchanged. According to the determined BTEX ratios and interspecies correlations, in contrast to the previous study, traffic was identified as the main emission source in the urban and control areas and showed an increased influence in the industrial area. The LCR, calculated for benzene, styrene, and tetrachloroethylene, shows a decrease of one order of magnitude in accordance to the decreased total VOC concentrations and is now acceptable according to values proposed by the World Health Organization.