Abstract
The city of Athens, as most large cities all over the world has air pollution problems. These problems were made worse by bad town layout, area geomorphology (surrounded by mountains) intense sunlight and low winds speed. Main goal of the present Thesis was to assess the exposure of inhabitants of Athens city in aromatic hydrocarbons (AH) mainly benzene, toluene and xylene by monitoring selected occupational groups. Another goal was to identify prognostic factors of personal exposure and home levels. Finally an attempt was made to assess muconic acid, a benzene metabolite, as a possible biomarker of exposure in environmental benzene levels. Conclusions were based on data collected by repeated measurements of 50 persons and their homes (six times a year), yielding 1800 values totally. In addition daily diaries during each measurement period were used. Fifty persons were chosen from the following occupational groups: teachers, students, bus drivers, postmen and traffic policemen based on ...
The city of Athens, as most large cities all over the world has air pollution problems. These problems were made worse by bad town layout, area geomorphology (surrounded by mountains) intense sunlight and low winds speed. Main goal of the present Thesis was to assess the exposure of inhabitants of Athens city in aromatic hydrocarbons (AH) mainly benzene, toluene and xylene by monitoring selected occupational groups. Another goal was to identify prognostic factors of personal exposure and home levels. Finally an attempt was made to assess muconic acid, a benzene metabolite, as a possible biomarker of exposure in environmental benzene levels. Conclusions were based on data collected by repeated measurements of 50 persons and their homes (six times a year), yielding 1800 values totally. In addition daily diaries during each measurement period were used. Fifty persons were chosen from the following occupational groups: teachers, students, bus drivers, postmen and traffic policemen based on the assumption that the first two groups represent low exposure groups on the contrary to the other three. Non smokers volunteers with only environmental exposure were included in the study because high levels of AH were released in cigarette smoke and consequently is a strong confounding factor. It is found that: 1. Home levels benzene varied between 6.03 to 13.35 μg/m3 in six measurements periods and result in an annual mean of 10.19 μg/m3. Personal levels varied between 13.08 to 24.63 μg/m3 and the annual mean was 18.85 μg/m3. Urban levels in city center were even higher with an annual mean of 20.4 μg/m3. According to a European Union guideline entered into force on 13/12/2000 the limit value of benzene shall not exceed 10 μg/m3. 2. Surprisingly, indoor pollution level in Athens was half of AH levels in urban environment. This is probably due to homes spreading in Athens basin (many homes were located in distance from polluted city center) and to home factors related to climate (use of non absorbent materials for wall and floor covering). The fact that personal exposure is lower than environmental concentrations of benzene is mainly due to low indoor pollution. Consequently keeping environmental limit value for benzene shall offer protection to inhabitants on the contrary to other cities where people are exposed to concentrations of benzene that may be multiple as high as the urban average. 3. The same pattern with minor deviations holds for toluene and xylenes.4. Correlation between personal and home levels was weaker for benzene compared to other hydrocarbons and for summer measurement compared to other seasons for the reason that other factors irrelevant to indoor environment have a predominant role in exposure modelling. On the contrary to benzene home levels of toluene and xylenes comprised a significant proportion of individual exposure values. Our results suggest that outdoors work give the greater contribution to benzene exposure of Athens citizens. 5. Indoor air pollution and personal exposure were closely related to measurement period i.e. seasonal variation. The variation between seasons may be explained in large by differences in climate parameters. Wind speed seems to determine largely home levels but also personal exposure. 6. Among home factors, only proximity to busy road was important factor for indoor benzene levels. Proximity to benzene station and home location were important factors in univariate analysis but were excluded in multivariate analysis. Probably home characteristics in Greece account for this result. 7. Adjusted for seasonal or climate variation, significant prognostic factors of personal exposure were home levels and total time spent outdoors. Groups who spent most of work-time outdoors were found to be exposed to higher aromatic compound levels and this explains the strong relationship between occupation and personal levels of exposure. Furthermore this specific factor is responsible for leading to non significant relationships between occupation and personal exposures in multivariate analysis. Transportation means was also a significant prognostic factor of personal benzene and toluene levels. 8. Our results show that muconic acid, a benzene metabolite, was not a reliable biomarker in environmental exposure to benzene.
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