Shmool Jessie Lc, Michanowicz Drew R, Cambal Leah, Tunno Brett, Howell Jeffery, Gillooly Sara, Roper Courtney, Tripathy Sheila, Chubb Lauren G, Eisl Holger M, Gorczynski John E, Holguin Fernando E, Shields Kyra Naumoff, Clougherty Jane E
Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA, USA.
Environ Health. 2014 Apr 16;13(1):28. doi: 10.1186/1476-069X-13-28.
Characterizing intra-urban variation in air quality is important for epidemiological investigation of health outcomes and disparities. To date, however, few studies have been designed to capture spatial variation during select hours of the day, or to examine the roles of meteorology and complex terrain in shaping intra-urban exposure gradients.
We designed a spatial saturation monitoring study to target local air pollution sources, and to understand the role of topography and temperature inversions on fine-scale pollution variation by systematically allocating sampling locations across gradients in key local emissions sources (vehicle traffic, industrial facilities) and topography (elevation) in the Pittsburgh area. Street-level integrated samples of fine particulate matter (PM2.5), black carbon (BC), nitrogen dioxide (NO2), sulfur dioxide (SO2), and ozone (O3) were collected during morning rush and probable inversion hours (6-11 AM), during summer and winter. We hypothesized that pollution concentrations would be: 1) higher under inversion conditions, 2) exacerbated in lower-elevation areas, and 3) vary by season.
During July - August 2011 and January - March 2012, we observed wide spatial and seasonal variability in pollution concentrations, exceeding the range measured at regulatory monitors. We identified elevated concentrations of multiple pollutants at lower-elevation sites, and a positive association between inversion frequency and NO2 concentration. We examined temporal adjustment methods for deriving seasonal concentration estimates, and found that the appropriate reference temporal trend differs between pollutants.
Our time-stratified spatial saturation approach found some evidence for modification of inversion-concentration relationships by topography, and provided useful insights for refining and interpreting GIS-based pollution source indicators for Land Use Regression modeling.
描述城市内部空气质量变化对于健康结果和差异的流行病学调查很重要。然而，迄今为止，很少有研究旨在捕捉一天中特定时段的空间变化，或研究气象学和复杂地形在形成城市内部暴露梯度中的作用。
我们设计了一项空间饱和监测研究，以针对当地空气污染源，并通过系统地在匹兹堡地区关键本地排放源（车辆交通、工业设施）和地形（海拔）的梯度上分配采样位置，来了解地形和温度逆温对细尺度污染变化的作用。在夏季和冬季的早高峰时段以及可能出现逆温的时段（上午6点至11点），收集了细颗粒物（PM2.5）、黑碳（BC）、二氧化氮（NO2）、二氧化硫（SO2）和臭氧（O3）的街道层面综合样本。我们假设污染浓度将：1）在逆温条件下更高，2）在低海拔地区加剧，3）随季节变化。
在2011年7月至8月和2012年1月至3月期间，我们观察到污染浓度存在广泛的空间和季节变化，超过了在监管监测器上测得的范围。我们在低海拔站点发现多种污染物浓度升高，并且逆温频率与二氧化氮浓度之间存在正相关。我们研究了用于得出季节浓度估计值的时间调整方法，发现不同污染物的适当参考时间趋势有所不同。
我们的时间分层空间饱和方法发现了一些证据，表明地形对逆温 - 浓度关系有影响，并为完善和解释基于地理信息系统的土地利用回归建模污染源指标提供了有用的见解。
