Intra-Urban Exposure to PM2.5 in Mexico City Associated with Acute Cardiovascular and Cerebrovascular Mortality from 2004-2013

Abstract

Background. Limited evidence exists about short-term exposure to different intra-urban concentration levels and composition of particulate matter with aerodynamic diameter ≤2.5µm (PM2.5) associated with acute cardiovascular and cerebrovascular mortality.Methods. We used an ecologic approach and Generalized Linear Mixed Models (GLMM) with Poisson regressions in order to assess daily exposure to PM2.5 associated with all cardiovascular, all cerebrovascular and ischemic heart mortality in people ≥25 and ≥65 years for each one of the sixteen boroughs of Mexico City for the period from 2004-2013. Exposure to PM2.5 was evaluated with estimates from a new hybrid spatiotemporal model using satellite measurements of Aerosol Optical Depth (AOD-PM2.5) with resolution of 1 km2 from NASA for same day exposure (lag0), and average of the current and previous day (lag0-1). The high spatial resolution of this model also allowed for the daily borough-level PM2.5 mean estimates to be weighted to account for population density. Spatial heterogeneity was tested by comparing the significance of the inclusion of the random-intercepts and random-slopes terms versus only the inclusion of the random-intercept term in our GLMM.Results. Exposure to AOD-PM2.5 varied from 21.6 μg/m3 to 26.9 μg /m3. A 10-μg/m3 increase in AOD-PM2.5 was associated with all cardiovascular mortality [0.2% (95%CI:0.11-0.29) to 2.3% (95%CI:2.19-2.39), increase], all cerebrovascular mortality [0.4%(95%CI:0.05-0.69) to 2.1% (95%CI:1.79-2.49), increase] and ischemic heart disease [0.6% (95%CI:0.6-0.68) to 3.8% (95%CI:3.77-3.91)] for lag0. Cerebrovascular mortality in people ≥65 showed the strongest associations for lag0 and lag0-1. Cardiovascular mortality in people ≥25 years was the only mortality outcome showing significant spatial heterogeneity.Conclusion. Intra-urban variation in PM2.5 concentration was associated with acute cardiovascular and cerebrovascular mortality within Mexico City.