Pollution and Later-Life Mortality
Friday, Jan. 6, 2017 1:00 PM – 3:00 PM
- Chair: Janet M. Currie, Princeton University and NBER
As the Wind Blows: The Effects of Long-Term Exposure to Air Pollution on Mortality
AbstractThere is strong evidence that short-run fluctuations in air pollution negatively impact infant health and contemporaneous adult health, but there is less evidence on the causal link between long-term exposure to air pollution and increased adult mortality. This project estimates the impact of long-term exposure to air pollution on mortality by leveraging quasi-random variation in pollution levels generated by wind patterns near major highways. We combine geocoded data on the residence of every decedent in Los Angeles over three years, high-frequency wind data, and Census Short Form data. Using these data, we estimate the effect of downwind exposure to highway-generated pollutants on the age-specific mortality rate by using bearing to the nearest major highway as an instrument for pollution exposure. We find that doubling the percentage of time spent downwind of a highway increases mortality among individuals 75 and older by 3.6 to 6.8 percent. These estimates are robust and economically significant.
Air Pollution and Procyclical Mortality: Causal Evidence From Thermal Inversions
AbstractWe estimate the causal influence of air quality in explaining pro-cyclical mortality across the United States in a dataset spanning nearly 300 cities over the period 1979-2013. Prior research has documented that accounting for air pollution attenuates the elasticity of mortality with respect to unemployment rates by up to 30% (Heutel and Ruhm, 2013). To isolate the causal influence of air pollution, we construct an instrumental variable (IV) based on atmospheric phenomena known as thermal inversions which induce non-anthropogenic variation in ground-level air pollution levels. Our identification strategy relies on comparing mortality rates across counties that experienced similar business cycles, but were subject to different intensity and frequency of inversions. This allows us to disentangle the air-pollution mechanism from other forces which may link business cycles and health.
Long Run Effects of Pollution: Evidence From the United States Acid Rain Program
AbstractMortality improvements attributed to environmental regulation represent a considerable share of the total benefits, but are largely based on correlational analyses that fail to account for optimizing behavior. While a growing body of evidence supports a causal effect from short-run exposure to pollution on infant mortality, there is limited causal evidence of the effects from long-run pollution exposure on adult mortality. In this paper, we exploit quasi-experimental variation in pollution induced by the US Acid Rain Program, which led to plausibly exogenous decreases in SO2 and other correlated pollutants. Furthermore, this regulation effected a vast geographic area spanning hundreds of miles, greatly limiting the scope for selective migration. In treated counties, we find significant decreases in mortality rates, followed by persistently lower mortality rate, suggesting long-run improvements in mortality. We find that a one part-per-billion reduction in ambient SO2 translates to 0.06 fewer deaths per 1,000 adult population, a decrease of approximately 1% of baseline mortality. Effects are largest for cardiovascular deaths, with no detectable effects for external causes, both of which support pollution exposure as the relevant mechanism. Our results are robust to numerous specification and falsification checks. These preliminary findings, while informative for the cost-benefit calculation of the Acid Rain Program, are also highly relevant for the new Clean Power Rule proposed by the EPA to further limit emissions from power plants in an effort to curb greenhouse gas emissions.
- Q5 - Environmental Economics