New evidence on the impact of sustained exposure to air pollution on life expectancy from China’s Huai River Policy

Avraham Ebenstein, Maoyong Fan, Michael Greenstone, Guojun He, and Maigeng Zhou
PNAS September 26, 2017 114 (39) 10384-10389; published ahead of print September 11, 2017 https://doi.org/10.1073/pnas.1616784114

  1. Edited by William C. Clark, Harvard University, Cambridge, MA, and approved July 3, 2017 (received for review October 27, 2016)

Significance

An estimated 4.5 billion people are currently exposed to particulate matter (PM) levels at least twice the concentration that the WHO considers safe. Existing evidence linking health to air pollution is largely based on populations exposed to only modest levels of PM and almost entirely composed of observational studies, which are likely to confound air pollution with other unobserved determinants of health. This study uses quasiexperimental variation in particulate matter smaller than 10 μm (PM10) generated by an arbitrary Chinese policy to find that a 10-μg/m3 increase in PM10 reduces life expectancy by 0.64 years. The estimates imply that bringing all of China into compliance with its Class I standards for PM10 would save 3.7 billion life-years.

Abstract

This paper finds that a 10-μg/m3 increase in airborne particulate matter [particulate matter smaller than 10 μm (PM10)] reduces life expectancy by 0.64 years (95% confidence interval = 0.21–1.07). This estimate is derived from quasiexperimental variation in PM10 generated by China’s Huai River Policy, which provides free or heavily subsidized coal for indoor heating during the winter to cities north of the Huai River but not to those to the south. The findings are derived from a regression discontinuity design based on distance from the Huai River, and they are robust to using parametric and nonparametric estimation methods, different kernel types and bandwidth sizes, and adjustment for a rich set of demographic and behavioral covariates. Furthermore, the shorter lifespans are almost entirely caused by elevated rates of cardiorespiratory mortality, suggesting that PM10 is the causal factor. The estimates imply that bringing all of China into compliance with its Class I standards for PM10 would save 3.7 billion life-years.

Footnotes

  • ↵1A.E., M.F., M.G., G.H., and M.Z. contributed equally to this work.

  • ↵2To whom correspondence should be addressed. Email: mgreenst{at}uchicago.edu.

  • Author contributions: A.E., M.F., M.G., G.H., and M.Z. designed research, performed research, contributed new reagents/analytic tools, analyzed data, and wrote the paper.

  • The authors declare no conflict of interest.

  • This article is a PNAS Direct Submission.

  • Data deposition: The measures of PM10 for each DSP location and the program files that produce the tables and figures have been posted as Dataset S1. Mortality measurements are available upon request and at the discretion of the Chinese Center for Disease Control and Prevention.

  • This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1616784114/-/DCSupplemental.

Freely available online through the PNAS open access option.

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Particulate matter exposure and life expectancy
Avraham Ebenstein, Maoyong Fan, Michael Greenstone, Guojun He, Maigeng Zhou
Proceedings of the National Academy of Sciences Sep 2017, 114 (39) 10384-10389; DOI: 10.1073/pnas.1616784114
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