Levy J I, Hammitt J K, Spengler J D
Departments of Environmental Health and Biostatistics, Harvard School of Public Health, Boston, Massachusetts 02115, USA.
Environ Health Perspect. 2000 Feb;108(2):109-17. doi: 10.1289/ehp.00108109.
Epidemiologic studies of the link between particulate matter (PM) concentrations and mortality rates have yielded a range of estimates, leading to disagreement about the magnitude of the relationship and the strength of the causal connection. Previous meta-analyses of this literature have provided pooled effect estimates, but have not addressed between-study variability that may be associated with analytical models, pollution patterns, and exposed populations. To determine whether study-specific factors can explain some of the variability in the time-series studies on mortality from particulate matter [less than/equal to] 10 microm in aerodynamic diameter (PM(10)), we applied an empirical Bayes meta-analysis. We estimate that mortality rates increase on average by 0.7% per 10 microg/m(3) increase in PM(10) concentrations, with greater effects at sites with higher ratios of particulate matter [less than/equal to] 2.5 microm in aerodynamic diameter (PM(2.5))/PM(10). This finding did not change with the inclusion of a number of potential confounders and effect modifiers, although there is some evidence that PM effects are influenced by climate, housing characteristics, demographics, and the presence of sulfur dioxide and ozone. Although further analysis would be needed to determine which factors causally influence the relationship between PM(10) and mortality, these findings can help guide future epidemiologic investigations and policy decisions.
关于颗粒物（PM）浓度与死亡率之间联系的流行病学研究得出了一系列估计结果，这导致了对于二者关系的大小以及因果联系强度存在分歧。以往对该文献的荟萃分析提供了合并效应估计值，但未涉及可能与分析模型、污染模式及暴露人群相关的研究间变异性。为了确定特定研究因素是否能解释粒径小于或等于10微米的颗粒物（PM10）死亡率时间序列研究中的部分变异性，我们应用了经验贝叶斯荟萃分析。我们估计，PM10浓度每增加10微克/立方米，死亡率平均上升0.7%，在空气动力学直径小于或等于2.5微米的颗粒物（PM2.5）/PM10比值较高的地点影响更大。纳入一些潜在混杂因素和效应修饰因素后，这一发现并未改变，不过有证据表明PM效应受气候、住房特征、人口统计学以及二氧化硫和臭氧的存在影响。尽管需要进一步分析以确定哪些因素对PM10与死亡率之间的关系有因果影响，但这些发现有助于指导未来的流行病学调查和政策决策。
