The Concentration-Response between Long-Term PM2.5 Exposure and Mortality: A Meta-Regression Approach

摘要

Long-term exposure to ambient fine particulate matter (< 2.5 μg/m3 in aerodynamic diameter; PM2.5) is significantly associated with increased risk of premature mortality. We provide an updated meta-analysis of all-cause and cause specific mortality associated with exposure to PM2.5 as a function of air pollution levels. We systematically searched all published cohort studies examining the association between long-term exposure to PM2.5 and mortality. We applied multivariate linear random effects meta-analysis with nested structure for cohort and study as random effects. Meta-regression techniques applied to test whether study population or analytic characteristics modify the PM2.5 -mortality association and to estimate the shape of the concentration-response curve. A total of 53 studies (39 from North America, 8 from Europe, and 6 from Asia) that provided 135 estimates of the association between the risk of mortality and exposure to PM2.5 were included in the meta-analysis. Since 2015,17 new studies have been published, covering geographic areas with a wider range of mean exposures (e.g. <12 or > 20 μg /m3). A penalized spline showed the slope decreased at higher concentrations but appeared to level off. We found that the inverse transform of average PM2.5 well approximated that spline and provided a parametric estimate that fit better than a linear or logarithmic term for average PM2.5. In addition, we found that exposure assessments using space time models or fixed monitors at Zip-code scale, or additionally controlling for area level socio-economic status were associated with higher effect estimates. This meta-analysis provides a strong evidence for the adverse effect of PM2.5 on mortality, that studies with poorer exposure have lower effect size estimates, and that more control for SES increases effect size estimates. The concentration -response function produced here can be further applied in the global health risk assessment of air particulate matter.