Estimated aerosol radiative and health effects of the residential coal ban in the Beijing-Tianjin-Hebei region of China

Particle-phase air pollution is a leading risk factor for premature death globally and impacts climate by scattering or absorbing radiation and changing cloud properties. In the Beijing-Tianjin-Hebei (BTH) region of China, where there are severe air quality problems, the government is implementing a ban on household use of coal for space heating, coupled with a subsidy for electric- or gas-powered heat pumps. We used the GEOS-Chem-TOMAS model, at 0.25°x0.3125° resolution to evaluate the potential impacts of this policy on air quality, mortality, and climate. We quantified the impacts of two different scenarios: (1) a complete transition away from the use of residential coal in the Beijing province (Beijing-transition case) and (2) a complete transition away from the use of residential coal in all the BTH provinces (BTH-transition case). We estimate that the PM 2.5 reductions would result in 2,100 (95% CI: 1,400-2,900) premature deaths avoided annually in the Beijing-transition case and 16,200 (95% CI: 10,700-22,600) in the BTH-transition case. We also estimate that removing residential coal use would result in a positive direct radiative effect (DRE), under two mixing state assumptions (external and core-shell), and a small positive cloud-albedo indirect effect (AIE). The effect is smaller in the Beijing-transition case (mean value across the model domain for external DRE: +0.029 W/m 2 ; core-shell DRE: +0.022 W/m 2 ; AIE: <+0.001 W/m 2 ) than in the BTH-transition case (mean external DRE = +0.349 W/m 2 ; core-shell DRE: +0.280 W/m 2 ; AIE: +0.004 W/m 2 ). Finally, we tested how the composition of the emissions from the residential coal sector might influence our radiative effect calculations. We found that if we doubled the black carbon to organic aerosol ratio (BC:OA) of residential coal there was a negative forcing over the BTH region under the core-shell mixing state assumption in the BTH-transition scenario (minimum value in the model domain for the core-shell DRE: -0.946 W/m 2 ).