Radiative Forcing and Health Impact of Aerosols and Ozone in China as the Consequence of Clean Air Actions over 2012–2017.

We applied the chemical transport model GEOS‐Chem to examine the changes in aerosols and tropospheric O3 in China from 2012–2017 and the associated radiative forcing and health impact. Simulated surface layer concentrations and column burdens of aerosols and O3 were evaluated by comparing with ground‐based and satellite‐retrieved measurements. Between 2012 and 2017, simulated annual mean concentrations of PM2.5 decreased by 21.0%, while O3 increased by 11.9% over eastern China (20–45°N, 105–122.5°E). Changes in aerosols and O3 over 2012–2017 jointly exerted a positive radiative forcing of 1.26 W/m2 over eastern China, which was dominated by the less cooling from PM2.5 reductions (1.18 W/m2). The Global Exposure Mortality Model predicted 268.3 (247.3–291.6) thousand (9.6%) fewer deaths in eastern China in 2017 relative to 2012. These results suggest an appreciable health benefit and a potential warming as a consequence of clean air actions. Plain Language Summary: Stringent clean air actions have been implemented in China since 2013, aiming to improve air quality. As a result, observed concentrations of aerosols decreased while those of O3 increased in eastern China. In this work we assess the radiative forcing and health impact resulted from the changes in aerosols and O3 in China for the period of 2012–2017 by using a chemical transport model. The model reproduces the observed changes in PM2.5 and O3 in recent years and estimates a net positive radiative forcing of 1.26 W/m2 in 2017 relative to 2012 over eastern China. Further estimates from the mortality model show that approximately 270,000 deaths are avoided. Results from our study suggest an appreciable health benefit as well as a potential warming as a consequence of clean air actions over 2012–2017. Key Points: Concentrations of PM2.5 decreased, and those of O3 increased as a result of air pollution control over 2012–2017Changes in PM2.5 and O3 led to a positive radiative forcing of 1.26 W/m2 over eastern China (20–45°N, 105–122.5°E)Changes in air pollution exposures are estimated to avoid 268.3 thousand deaths in eastern China [ABSTRACT FROM AUTHOR]