Hazed and Confused: The Effect of Air Pollution on Dementia
We find that long-term exposure to fine-particulate air pollution (PM2.5) degrades health and human capital among older adults by increasing their risk of developing Alzheimer’s disease and related dementias. We track U.S. Medicare beneficiaries’ cumulative residential exposures to PM2.5 and their health from 2004 through 2013, leveraging within- and between-county quasi-random variation in PM2.5 resulting from the expansion of Clean Air Act regulations. We find that a 1 ìg/m3 increase in decadal PM2.5 increases the probability of a dementia diagnosis by 1.68 percentage points. The effects are as large or larger when we adjust for mortality-based sample selection and additional Tiebout-sorting dynamics. We do not find relationships between decadal PM2.5 and placebo outcomes. Our estimates suggest that the federal regulation led to nearly 182,000 fewer people with dementia in 2013, yielding $214 billion in benefits. Further, PM2.5’s effect on dementia persists below the current regulatory thresholds.
We are grateful for insights and suggestions from Spencer Banzhaf, Richard Carson, Tatayana Deryugina, Olivier Deschenes, Katrina Jessoe, Michael Greenstone, David Kelly, Alan Krupnick, Daniel McFadden, Alvin Murphy, Laura Schechter, and seminar audiences at the AERE Summer meeting, the Annual Health Economics Conference, the ASHEcon conference, Society for Consumer Psychology Conference, the IHEA Congress, USC Health Economics conference, UC Santa Barbara Occasional Workshop, Arizona State University, Colorado School of Mines, Emory University, Georgia State University, London School of Economics, Oxford University, Resources for the Future, Tinbergen Institute, Tulane University, University of Arizona, University of Braga, UC Berkeley, UC Davis, UC San Diego, University of Chicago, University of Copenhagen, University of Kentucky, University of Wisconsin, Virginia Tech and Yale. The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research.
- The EPA’s decision to regulate fine-particulate air pollution in 2005 reduced the number of dementia cases in the United States in...