Environmental Pollution ( IF 6.792 ) Pub Date : 2021-02-16 , DOI: 10.1016/j.envpol.2021.116763 Jianzhao Bi; Lance A. Wallace; Jeremy A. Sarnat; Yang Liu
Epidemiological research on the adverse health outcomes due to PM2.5 exposure frequently relies on measurements from regulatory air quality monitors to provide ambient exposure estimates, whereas personal PM2.5 exposure may deviate from ambient concentrations due to outdoor infiltration and contributions from indoor sources. Research in quantifying infiltration factors (Finf), the fraction of outdoor PM2.5 that infiltrates indoors, has been historically limited in space and time due to the high costs of monitor deployment and maintenance. Recently, the growth of openly accessible, citizen-based PM2.5 measurements provides an unprecedented opportunity to characterize Finf at large spatiotemporal scales. In this analysis, 91 consumer-grade PurpleAir indoor/outdoor monitor pairs were identified in California (41 residential houses and 50 public/commercial buildings) during a 20-month period with around 650000 h of paired PM2.5 measurements. An empirical method was developed based on local polynomial regression to estimate site-specific Finf. The estimated site-specific Finf had a mean of 0.26 (25th, 75th percentiles: [0.15, 0.34]) with a mean bootstrap standard deviation of 0.04. The Finf estimates were toward the lower end of those reported previously. A threshold of ambient PM2.5 concentration, approximately 30 μg/m3, below which indoor sources contributed substantially to personal exposures, was also identified. The quantified relationship between indoor source contributions and ambient PM2.5 concentrations could serve as a metric of exposure errors when using outdoor monitors as an exposure proxy (without considering indoor-generated PM2.5), which may be of interest to epidemiological research. The proposed method can be generalized to larger geographical areas to better quantify PM2.5 outdoor infiltration and personal exposure.
关于由于暴露于PM 2.5而造成的不利健康后果的流行病学研究通常依赖于监管空气质量监测仪的测量结果来提供环境暴露估计值，而由于室外渗透和室内来源的影响，个人PM 2.5暴露量可能会偏离环境浓度。由于监控器的部署和维护成本高昂，因此在空间和时间上一直对限制渗透因子（F inf）（室外PM 2.5渗透到室内的比例）进行研究。最近，基于公民的可公开访问的PM 2.5测量值的增长为表征F inf提供了前所未有的机会在较大的时空尺度上。在此分析中，在20个月的时间里，通过约650000 h的配对PM 2.5测量，在加利福尼亚州（共41栋住宅和50栋公共/商业建筑）确定了91对消费级的PurpleAir室内/室外监控器对。基于局部多项式回归开发了一种经验方法来估计特定于站点的F inf。估计的位点特异性F inf平均值为0.26（第25、75个百分位数：[0.15，0.34]），平均自举标准偏差为0.04。F inf估计接近先前报告的较低端。大气中PM 2.5浓度的阈值，大约30μg/ m在图3中，还确定了室内来源在很大程度上导致了个人暴露。当使用室外监测仪作为暴露指标（不考虑室内产生的PM 2.5）时，室内污染源贡献与周围PM 2.5浓度之间的量化关系可以用作暴露误差的量度，这可能是流行病学研究的重点。所提出的方法可以推广到更大的地理区域，以更好地量化PM 2.5的室外渗透和个人暴露。