An integrated modelling framework for evaluating the synergistic impacts of low-carbon transitions and air pollution controls on air quality and health in Guangzhou, China

Climate policies that target carbon emissions can induce co-benefits for air quality. Previous urban studies have typically focused on either carbon reduction or air pollution control independently, but few have examined their combined effects on reducing carbon emissions and consequential environmental gains. We develop an integrated modelling framework to assess the impacts of different low-carbon transitions and end-of-pipe controls on PM 2.5 and ozone concentrations and associated premature mortality in the megacity of Guangzhou. The results show that the implementation of both deep carbon mitigation and aggressive air pollution control policies can reduce the city's pollutant emissions to 34%–51% of the 2020 levels by 2035. Consequently, the population-weighted PM 2.5 concentration in 2035 is projected to decrease by 5 μg/m 3 compared to the 2035 baseline scenario. However, the ozone concentration is expected to rise by 35 μg/m 3 due to the reduced titration effect of NO on ozone. These changes are estimated to prevent approximately 3.0 thousand (95% CI: 2.0–3.9) PM 2.5 -related premature deaths, while increasing ozone-related premature deaths by approximately 1.6 thousand (95% CI: 0.7–2.7). Moreover, implementing multiregional integrated control measures in Guangzhou and its neighbouring cities yields greater air quality and health benefits for Guangzhou compared to local enforcement alone, resulting in 1.5 times more avoided PM 2.5 -related premature deaths. Additionally, the increase in ozone-related premature deaths from these cooperative emission control strategies is merely 0.3 times the figure observed under local enforcement alone. The transport and industry sectors play a crucial role in reducing air pollutant emissions, whereas reductions in the solvent use sector can help mitigate the adverse effects of reduced NO x on ozone pollution. These findings highlight the need for comprehensively multiregional strategies to balance the trade-offs between reducing PM 2.5 and ozone-related health impacts, offering valuable insights for urban policy makers aiming to optimize both climate and air quality goals on a broader scale.