Mitigating China’s Ozone Pollution with More Balanced Health Benefits

Abstract

China is confronting the challenge of opposite health benefits (OHBs) during ambient ozone (O3) mitigation because the same reduction scheme might yield opposite impacts on O3 levels and associated public health across different regions. Here, we used a combination of chemical transport modeling, health benefit assessments, and machine learning to capture such OHBs and optimize O3 mitigation pathways based on 121 control scenarios. We revealed that, for the China mainland, Beijing–Tianjin–Hebei and its surroundings (“2 + 26” cities), Yangtze River Delta, and Pearl River Delta, there could be at most 2897, 920, 1247, and 896 additional O3-related deaths in urban areas, respectively, accompanying 21,512, 3442, 5614, and 642 avoided O3-related deaths in rural areas, respectively, at the same control stage. Additionally, potential disbenefits during O3 mitigation were “pro-wealthy”, that is, residents in developed regions are more likely to afford additional health risks. In order to avoid OHBs during O3 abatement, we proposed a two-phase control strategy, whereby the reduction ratio of NO X (nitrogen oxide) to VOCs (volatile organic compounds) was adjusted according to health benefit distribution patterns. Our study provided novel insights into China’s O3 attainment and references for other countries facing the dual challenges of environmental pollution and associated inequality issues.

Cost-Effectiveness of NOX and VOC Co-operative Controls for PM2.5 and O3 Mitigation in the Context of China’s Carbon Neutrality

“…However, regarding city cluster, the area of PRD (201 grids) is much smaller than that of 2 + 26 cities (819 grids) and PRD (1029 grids), and thus, the urban concentration of PRD is denser, resulting in its overall higher NO X emission intensity, and in turn leading to the heightened sensitivity of O 3 to AVOCs. 11 Correspondingly, cumulative health benefits due to the abatement of O 3 among four scenarios differ more significantly compared to that due to PM 2.5 abatement (Figure 2d). Citing PRD as a typical, cumulative health benefits due to PM 2.5 abatement under NO X -only decreased by 19.0% compared to that under NO X -AVOC-A, while this number is 76.2% in regard to cumulative health benefits due to O 3 abatement.…”

“…Given that, we constructed the HB scenario based on a health balanced pathway to O 3 mitigation in our previous work. 11 The HB follows the pathway where NO X /AVOC reduction ratios are maximized, while avoiding the rebounding of O 3related mortality. The HB can thus be regarded as a strategy that achieves co-operative controls with the minimum cost for AVOC controls.…”

“…O 3 pollution could be exacerbated or mitigated across different regions, resulting in regional health inequality. Given that, we constructed the HB scenario based on a health balanced pathway to O 3 mitigation in our previous work . The HB follows the pathway where NO X /AVOC reduction ratios are maximized, while avoiding the rebounding of O 3 -related mortality.…”

“…In contrast, a reduction in NO X emissions may paradoxically exacerbate O 3 pollution, namely "NO X disbenefits". 10,11 As such, the key to simultaneous declines of PM 2.5 and O 3 is the co-operative controls of NO X and AVOCs, with the reduction ratio of NO X to AVOCs being central. 12 In fact, mountains of literature have emphasized the importance of moderate NO X /AVOC reduction ratios, such as 1:2 13 and 1:3.…”

“…The response of PM 2.5 pollution levels to NO X and AVOCs is monotonic, that is, the more precursor reductions there are, the more PM 2.5 declines. In contrast, a reduction in NO X emissions may paradoxically exacerbate O 3 pollution, namely “NO X disbenefits”. , As such, the key to simultaneous declines of PM 2.5 and O 3 is the co-operative controls of NO X and AVOCs, with the reduction ratio of NO X to AVOCs being central …”