Several papers reported associations between airborne fine particulate matter (PM2.5) and birth weight, though findings are inconsistent across studies. Conflicting results might be due to (1) different PM2.5 chemical structure across locations, and (2) various exposure assignment methods across studies even among the studies that use ambient monitors to assess exposure. We investigated associations between birth weight and PM2.5 chemical constituents, considering issues arising from choice of buffer size (i.e. distance between residence and pollution monitor). We estimated the association between each pollutant and term birth weight applying buffers of 5 to 30km in Connecticut (2000-2006), in the New England region of the U.S. We also investigated the implication of the choice of buffer size in relation to population characteristics, such as socioeconomic status. Results indicate that some PM2.5 chemical constituents, such as nitrate, are associated with lower birth weight and appear more harmful than other constituents. However, associations vary with buffer size and the implications of different buffer sizes may differ by pollutant. A homogeneous pollutant level within a certain distance is a common assumption in many environmental epidemiology studies, but the validity of this assumption may vary by pollutant. Furthermore, we found that areas close to monitors reflect more minority and lower socio-economic populations, which implies that different exposure approaches may result in different types of study populations. Our findings demonstrate that choosing an exposure method involves key tradeoffs of the impacts of exposure misclassification, sample size, and population characteristics.

中文翻译：

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空气中 PM2.5 化学成分与出生体重之间的关联——缓冲暴露分配的意义

几篇论文报告了空气中细颗粒物 (PM2.5) 与出生体重之间的关联，但研究结果并不一致。相互矛盾的结果可能是由于 (1) 不同地点的 PM2.5 化学结构不同，以及 (2) 即使在使用环境监测器评估暴露的研究中，研究之间的暴露分配方法也不同。我们调查了出生体重和 PM2.5 化学成分之间的关​​联，考虑到缓冲区大小（即居住地和污染监测器之间的距离）的选择引起的问题。我们在美国新英格兰地区的康涅狄格州 (2000-2006) 应用 5 至 30 公里的缓冲区估计了每种污染物与足月出生体重之间的关联我们还调查了缓冲区大小选择与人口特征相关的含义，比如社会经济地位。结果表明，一些 PM2.5 化学成分，如硝酸盐，与较低的出生体重有关，而且似乎比其他成分更有害。然而，关联因缓冲区大小而异，不同缓冲区大小的影响可能因污染物而异。一定距离内的同质污染物水平是许多环境流行病学研究中的常见假设，但该假设的有效性可能因污染物而异。此外，我们发现靠近监测器的区域反映了更多的少数民族和较低的社会经济人口，这意味着不同的暴露方法可能会导致不同类型的研究人群。我们的研究结果表明，选择暴露方法涉及暴露错误分类、样本大小、