Department of Public Health Sciences, A210 Penn State College of Medicine 600 Centerview Drive, Suite 2200 Hershey, Pennsylvania 17033-0855, United States.
Environ Sci Technol. 2012 Jul 17;46(14):7612-20. doi: 10.1021/es3010305. Epub 2012 Jul 5.
Differences in the toxicity of ambient particulate matter (PM) due to varying particle composition across locations may contribute to variability in results from air pollution epidemiologic studies. Though most studies have used PM mass concentration as the exposure metric, an alternative which accounts for particle toxicity due to varying particle composition may better elucidate whether PM from specific sources is responsible for observed health effects. The oxidative potential (OP) of PM < 10 μm (PM(10)) was measured as the rate of depletion of the antioxidant reduced glutathione (GSH) in a model of human respiratory tract lining fluid. Using a database of GSH OP measures collected in greater London, U.K. from 2002 to 2006, we developed and validated a predictive spatiotemporal model of the weekly GSH OP of PM(10) that included geographic predictors. Predicted levels of OP were then used in combination with those of weekly PM(10) mass to estimate exposure to PM(10) weighted by its OP. Using cross-validation (CV), brake and tire wear emissions of PM(10) from traffic within 50 m and tailpipe emissions of nitrogen oxides from heavy-goods vehicles within 100 m were important predictors of GSH OP levels. Predictive accuracy of the models was high for PM(10) (CV R(2)=0.83) but only moderate for GSH OP (CV R(2) = 0.44) when comparing weekly levels; however, the GSH OP model predicted spatial trends well (spatial CV R(2) = 0.73). Results suggest that PM(10) emitted from traffic sources, specifically brake and tire wear, has a higher OP than that from other sources, and that this effect is very local, occurring within 50-100 m of roadways.
由于不同地点的颗粒组成不同，环境颗粒物 (PM) 的毒性差异可能导致空气污染流行病学研究结果的变异性。虽然大多数研究都使用 PM 质量浓度作为暴露指标，但考虑到颗粒组成变化导致的颗粒毒性的替代指标可能更好地阐明特定来源的 PM 是否对观察到的健康影响负责。PM < 10 μm (PM(10)) 的氧化潜力 (OP) 是通过测量模型中人类呼吸道衬液中抗氧化还原型谷胱甘肽 (GSH) 的耗竭速率来测量的。使用 2002 年至 2006 年在英国伦敦收集的 GSH OP 测量数据库，我们开发并验证了 PM(10) 每周 GSH OP 的预测时空模型，其中包括地理预测因子。然后，使用预测的 OP 水平与每周 PM(10) 质量结合，估算 PM(10) 的暴露量，其权重为其 OP。使用交叉验证 (CV)，50 米内交通产生的 PM(10) 的刹车和轮胎磨损排放物以及 100 米内重型货车的氮氧化物排气管排放物是 GSH OP 水平的重要预测因子。模型对 PM(10) 的预测准确性很高 (CV R(2)=0.83)，但对 GSH OP 的预测准确性仅为中等 (CV R(2)=0.44)，当比较每周水平时；然而，GSH OP 模型很好地预测了空间趋势 (空间 CV R(2)=0.73)。结果表明，交通源排放的 PM(10)，特别是刹车和轮胎磨损，具有比其他来源更高的 OP，并且这种影响非常局部，发生在道路 50-100 米范围内。
