Comparison of Sources of Variability in School Age Children Exposure to Ambient PM2.5

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• 作者：W. W. Che ; H. Christopher Frey ; Alexis K. H. Lau
• 刊名：Environmental Science & Technology
• 出版年：2015
• 出版时间：February 3, 2015
• 年：2015
• 卷：49
• 期：3
• 页码：1511-1520
• 全文大小：355K
• ISSN：1520-5851

文摘

School age children are particularly susceptible to exposure to ambient fine particle (PM_2.5). To provide insight into factors affecting variability in ambient PM_2.5 exposure, distributions of daily PM_2.5 exposures for school age children are estimated for four seasons in three climatic zones of the United States using a stochastic microenvironmental exposure model, based on ambient concentration, air exchange rate, penetration factor, deposition rate, census data, meteorological data, and time pattern data. Estimated daily individual exposure varies largely among seasons, regions, and individuals. The mean ratio of ambient exposure to ambient concentration (E_a/C_a) ranges from 0.46 to 0.61 among selected regions and seasons, resulting from differences in air exchange rate. The individual E_a/C_a varies by a factor of 2 to 3 over a 95% frequency range among simulated children, resulting from variability in children鈥檚 time patterns. These patterns are similar among age groups, but vary with the day of the week and outdoor temperature. Variability in exposure is larger between individuals than between groups. The high end ratio of the E_a/C_a, at the 95th percentile of inter-individual variability, is 30% to 50% higher than the mean E_a/C_a ratio. Results can be used to intepret and adjust exposure errors in epidemiology and to assist in development of exposure mitigation strategies.