Adgate John L, Mongin Steven J, Pratt Gregory C, Zhang Junfeng, Field M Paul, Ramachandran Gurumurthy, Sexton Ken
Division of Environmental Health Sciences, School of Public Health, University of Minnesota, 420 Delaware St SE, MMC 807, Minneapolis, MN 55455, USA.
Sci Total Environ. 2007 Nov 1;386(1-3):21-32. doi: 10.1016/j.scitotenv.2007.07.007. Epub 2007 Aug 10.
Twenty-four hour average fine particle concentrations of 23 trace elements (TEs) were measured concurrently in (a) ambient air in three urban neighborhoods (Battle Creek-BCK; East St. Paul-ESP; and Phillips-PHI), (b) air inside residences of participants, and (c) personal air near the breathing zone of healthy, non-smoking adults. The outdoor (O), indoor (I), and personal (P) samples were collected in the Minneapolis/St. Paul metropolitan area over three seasons (Spring, Summer, Fall) using either the federal reference (O) or inertial impactor (I,P) inlets to collect PM(2.5). In addition to descriptive statistics, a hierarchical, mixed-effects statistical model was used to estimate the mutually adjusted effects of monitor location, community, and season on mean differences between monitoring locations while accounting for within-subject and within-monitoring period correlation. The relationships among P, I, and O concentrations varied across TEs. The O concentrations were usually higher than P or I for elements like Ca and Al that originate mainly from entrained crustal material, while P concentrations were often highest for other elements with non-crustal sources. Unadjusted mixed model results demonstrated that O monitors more frequently underestimated than overestimated P TE exposures for elements associated with non-crustal sources. This finding was true even though the O TE measurements were taken in the same neighborhoods as the P and I measurements. Further adjustment for community or season effects in the mixed models reduced the number of significant O-P and O-I differences compared to unadjusted models, but still indicated a tendency for underestimation of personal and indoor TE exposures by central site monitors, particularly in the PHI community. These results indicate that community and season are important covariates for developing long term TE exposure estimates, and that personal exposure to trace elements in PM(2.5) is likely to be underestimated by outdoor central site monitors.
在三个城市社区（巴特尔克里克 - BCK；东圣保罗 - ESP；菲利普斯 - PHI）的（a）环境空气中、（b）参与者住宅内的空气中以及（c）健康、不吸烟成年人呼吸区附近的个人空气中，同时测量了23种微量元素（TEs）的24小时平均细颗粒物浓度。在明尼阿波利斯/圣保罗都会区的三个季节（春季、夏季、秋季）收集室外（O）、室内（I）和个人（P）样本，使用联邦参考（O）或惯性撞击器（I、P）入口来收集PM(2.5)。除了描述性统计，还使用了分层混合效应统计模型来估计监测位置、社区和季节对监测位置之间平均差异的相互调整效应，同时考虑个体内部和监测期间内的相关性。P、I和O浓度之间的关系因TEs而异。对于主要源自夹带地壳物质的元素，如Ca和Al，O浓度通常高于P或I，而对于其他具有非地壳来源的元素，P浓度往往最高。未调整的混合模型结果表明，对于与非地壳来源相关的元素，O监测器低估P TE暴露的频率高于高估的频率。即使O TE测量是在与P和I测量相同的社区进行的，这一发现仍然成立。与未调整模型相比，在混合模型中进一步调整社区或季节效应减少了显著的O - P和O - I差异的数量，但仍表明中心站点监测器有低估个人和室内TE暴露的趋势，特别是在PHI社区。这些结果表明，社区和季节是制定长期TE暴露估计值的重要协变量，并且室外中心站点监测器可能低估了个人对PM(2.5)中微量元素的暴露。
