McMaster University, McMaster Institute for Transportation and Logistics, Hamilton, Ontario, Canada.
Ryerson University, Department of Geography and Environmental Studies, Toronto, Ontario, Canada.
Sci Total Environ. 2017 Dec 1;599-600:1813-1822. doi: 10.1016/j.scitotenv.2017.05.134. Epub 2017 May 20.
Previous investigations have reported intake fraction (iF) for different environments, which include ambient concentrations (outdoor exposure) and microenvironments (indoor exposure). However, little is known about iF variations due to space-time factors, especially in microenvironments. In this paper, we performed a spatio-temporal analysis of particulate matter (PM) intake fractions for vehicular emissions. Specifically, we investigated hourly variation (12:00am-11:00pm) by micro-environments (residences and workplaces) in the Greater Toronto and Hamilton Area (GTHA), Canada. We used GIS modeling to estimate air pollution data (ambient concentration, and traffic emission) and population data in each microenvironment. Our estimates showed that the total iF at residences and workplaces accounts for 85% and 15%, respectively. Workplaces presented the highest 24h average iF (1.06ppm), which accounted for 25% higher than residences. Observing the iF by hour at residences, our estimates showed the highest average iF at 2:00am (iF=3.72ppm). These estimates indicate that approximately 4g of PM emitted from motor vehicles are inhaled for every million grams of PM emitted. For the workplaces, the highest exposure was observed at 10:00am, with average iF equal to 2.04ppm. The period of the day with the lower average iF for residences was at 8:00am (average iF=0.11ppm), while for the workplaces was at 4:00am (average iF=0.47ppm). Our approach provides a new perspective on human exposure to air pollution. Our results showed significant hourly variation in iF across the GTHA. Our findings can be incorporated in future investigations to advance environmental health effects research and human health risk assessment.
先前的研究报告了不同环境下的摄入分数（iF），包括环境浓度（室外暴露）和微环境（室内暴露）。然而，由于时空因素，特别是在微环境中，人们对 iF 变化知之甚少。在本文中，我们对车辆排放的颗粒物（PM）摄入分数进行了时空分析。具体来说，我们研究了加拿大大多伦多和汉密尔顿地区（GTHA）的微环境（住宅和工作场所）的小时变化（12:00am-11:00pm）。我们使用 GIS 模型来估算每个微环境中的空气污染数据（环境浓度和交通排放）和人口数据。我们的估计表明，住宅和工作场所的总 iF 分别占 85%和 15%。工作场所呈现出最高的 24 小时平均 iF（1.06ppm），比住宅高 25%。观察住宅的 iF 按小时变化，我们的估计显示凌晨 2 点的平均 iF 最高（iF=3.72ppm）。这些估计表明，每百万克机动车排放的 PM 中，约有 4 克被吸入。对于工作场所，上午 10 点的暴露量最高，平均 iF 等于 2.04ppm。住宅平均 iF 较低的时段是上午 8 点（平均 iF=0.11ppm），而工作场所则是上午 4 点（平均 iF=0.47ppm）。我们的方法为人类暴露于空气污染提供了新的视角。我们的研究结果表明，GTHA 内的 iF 存在显著的小时变化。我们的研究结果可以纳入未来的研究中，以推进环境健康影响研究和人类健康风险评估。
