An analysis of factors that influence personal exposure to toluene and xylene in residents of Athens, Greece

BACKGROUND: Personal exposure to pollutants is influenced by various outdoor and indoor sources. The aim of this study was to evaluate the exposure of Athens citizens to toluene and xylene, excluding exposure from active smoking. METHODS: Passive air samplers were used to monitor volunteers, their homes and various urban sites for one year, resulting in 2400 measurements of toluene and xylene levels. Since both indoor and outdoor pollution contribute significantly to human exposure, volunteers were chosen from occupational groups who spend a lot of time in the streets (traffic policemen, bus drivers and postmen), and from groups who spend more time indoors (teachers and students). Data on individual and house characteristics were obtained using a questionnaire completed at the beginning of the study; a time-location-activity diary was also completed daily by the volunteers in each of the six monitoring campaigns. RESULTS: Average personal toluene exposure varied over the six monitoring campaigns from 53 to 80 μg/m(3). Urban and indoor concentrations ranged from 47 – 84 μg/m(3 )and 30 – 51 μg/m(3), respectively. Average personal xylene exposure varied between 56 and 85 μg/m(3 )while urban and indoor concentrations ranged from 53 – 88 μg/m(3 )and 27 – 48 μg/m(3), respectively. Urban pollution, indoor residential concentrations and personal exposures exhibited the same pattern of variation during the measurement periods. This variation among monitoring campaigns might largely be explained by differences in climate parameters, namely wind speed, humidity and amount of sunlight. CONCLUSION: In Athens, Greece, the time spent outdoors in the city center during work or leisure makes a major contribution to exposure to toluene and xylene among non-smoking citizens. Indoor pollution and means of transportation contribute significantly to individual exposure levels. Other indoor residential characteristics such as recent painting and mode of heating used might also contribute significantly to individual levels. Groups who may be subject to higher exposures (e.g. those who spent more time outdoors because of occupational activities) need to be surveyed and protected against possible adverse health effects

Gas/particle partitioning of seven volatile polycyclic aromatic hydrocarbons in a heavy traffic urban area

Air samples (vapor- and particle-phase) were taken for 19 sampling events during the period from December 1997 to July 1998 in an urban site in the center of Athens. The urban site is densely populated and characterized by heavy traffic circulation and elevated concentrations of VOCs, NOx CO and smoke. Seven volatile polycyclic aromatic hydrocarbons (PAHs) were determined in samples. The temperature dependence of gas-phase atmospheric concentration of PAHs, C-g, was investigated using diagrams of natural logarithm of partial pressures (in P) vs. reciprocal midpoint temperatures. For the six of seven volatile PAHs, the temperature dependence of In P was statistically significant (at least at the 90% confidence level) and the temperature accounted for 21-67% of the variability in gas-phase concentrations. The gas-phase concentration C-g of the very volatile PAHs was affected more significantly by changes in temperature, but the variation of the less-volatile PAHs fluoranthene and pyrene C-g was better explained by changes in temperature. The temperature dependence of gas/particle partitioning constant K, was also examined. Regressions of log(K,) vs. T-1 for fluorene, fluoranthene and pyrene were classified into two different temperature ranges. The gas/particle partitioning of PAHs was studied by correlating the partition constant to the sub-cooled liquid saturation vapor pressure (P-L(o)). The Junge adsorption model underestimated the particle fraction of volatile PAHs probably due to the presence of non-exchangeable fraction. Slopes (m(r)) of the regressions log K-p vs. log P-L(o), were different from the value - I as Pankow’s theory predicts. The short distance between the sampling point and the emission Sources is also estimated to be a factor that causes deviations from the theoretical value. Evidence that atmospheric conditions favorable for secondary aerosol formation coincide with higher value of m(r), was provided by limited sampling events. An interrelation was found to exist between the m(r) values, allowing the prediction of the gas/particle partitioning of a series of seven PAHs by the measurement of a single PAH partitioning. (C) 2003 Elsevier B.V. All rights reserved

Benzene: Environmental Exposure

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