Apr 15, 2016

Estimating Causal Effects of Long-Term PM2.5 Exposure on Mortality in New Jersey

Yan Wang, Itai Kloog, Brent A. Coull, Anna Kosheleva, Antonella Zanobetti, and Joel D. Schwartz
Environmental Health Perspectives
  • Estimates the causal effects of long-term PM2.5 effect on mortality and tested the effect modifications by seasonal temperatures, census-tract-level socio-economic variables, and county-level health conditions
  • Specifically, estimates the association between long-term exposure to PM2.5 and mortality controlling for geographical differences using dummy variables for each census tract in New Jersey, a state-wide time trend using dummy variables for each year from 2004 to 2009, and mean summer and winter temperatures for each tract in each year
  • Finds—for each interquartile range (2 µg/m3 ) increase in annual PM2.5—there was a 3.0% (95% confidence interval: 0.2, 5.9%) increase in all natural cause mortality for the whole population, with similar results for people older than 65 [3.5% (0.1, 6.9%)] and people 65 or younger [3.1% (-1.8, 8.2%)]
  • Finds mean summer temperature and mean winter temperature in a census tract significantly modified the effect of long-term exposure to PM2.5 on mortality
  • Observes a higher percentage increase in mortality associated with PM2.5 in census tracts with more blacks, lower home value, or lower median income
  • Identifies a causal effect of long-term PM2.5 on mortality which is modified by seasonal temperatures and ecological socio-economic status under the assumption of the difference-in-differences approach