Future Projection of Mortality From Exposure to PM2.5 and O3 Under the Carbon Neutral Pathway: Roles of Changing Emissions and Population Aging

A global chemical transport model GEOS-Chem was applied to examine the concentrations of PM2.5 and O-3 in China, related health burdens and the relative importance of changes in air pollutants and population aging over 2015-2060 under carbon neutral pathway (Shared Socioeconomic Pathway limiting end-of-century radiative forcing to 1.9 W m(-2), SSP1-1.9). Results showed synergistic reductions of 100.0%, 72.0%, and 24.4% in net CO2 emission, concentration of annual mean PM2.5, and the 90th maximum daily average 8-hr (MDA8) O-3 over China, respectively, during 2015-2060. Pollutants-related deaths owing to changes in pollutants and population were simulated to increase by 38.1% over 2015-2060 because of population aging. Over 2015-2060, sensitivity studies showed that the decline in pollutants alone would mitigate deaths by 5,172.7 thousand, while the population aging alone would increase deaths by 2,633.3 thousand. Carbon neutrality will avoid 3,520.0 thousand deaths in 2060 relative to a higher-carbon pathway (SSP5-8.5). Plain Language Summary The achievement of carbon neutrality by 2060, a goal proposed by Chinese government, will influence air quality and associated health burden in the future. Meanwhile, population aging is going to be a big challenge for the country to face. In this study, we assessed the changes in concentrations of PM2.5 and O-3 and associated health impacts of different age populations from 2015 to 2060 using GEOS-Chem model and exposure-response functions. Contributions to premature deaths due to decline in pollutants and population aging were further quantified, respectively. We also compared the results based on carbon neutrality (SSP1-1.9) with those simulated from a pathway with higher CO2 emission (SSP5-8.5) to figure out the environmental and health benefits of carbon neutrality. Our results suggested that the decline in PM2.5 and O-3 benefited from carbon neutrality would mitigate the increase in mortality owing to population aging from 2015 to 2060. The increase in premature deaths caused by population aging alone under SSP1-1.9 will be less than that under SSP5-8.5. Our study highlighted the importance of implementing carbon neutral measures from the environmental and health perspectives.