A Source-Oriented Approach to Coal Power Plant Emissions Health Effects

There is increasing focus on whether air pollution originating from different sources has different health implications. In particular, recent evidence suggests that fine particulate matter (PM2.5) with chemical tracers suggesting coal combustion origins is especially harmful. Augmenting this knowledge with estimates from causal inference methods to identify the health impacts of PM2.5 derived from specific point sources of coal combustion would be an important step towards informing specific, targeted interventions. We investigated the effect of high-exposure to coal combustion emissions from 783 coal-fired power generating units on ischemic heart disease (IHD) hospitalizations in over 19 million Medicare beneficiaries residing at 21,351 ZIP codes in the eastern United States. We used InMAP, a newly-developed, reduced-complexity air quality model to classify each ZIP code as either a high-exposed or control location. Our health outcomes analysis uses a causal inference method - propensity score matching - to adjust for potential confounders of the relationship between exposure and IHD. We fit separate Poisson regression models to the matched data in each geographic region to estimate the incidence rate ratio for IHD comparing high-exposed to control locations. High exposure to coal power plant emissions and IHD were positively associated in the Northeast (IRR = 1.08, 95% CI = 1.06, 1.09) and the Southeast (IRR = 1.06, 95% CI = 1.04, 1.08). No significant association was found in the Industrial Midwest (IRR = 1.02, 95% CI = 1.00, 1.04), likely the result of small exposure contrasts between high-exposed and control ZIP codes in that region. This study provides targeted evidence of the association between emissions from specific coal power plants and IHD hospitalizations among Medicare beneficiaries.