# National climate action can ameliorate, perpetuate, or exacerbate international air pollution inequalities

## TL;DR

Climate action can reduce air pollution deaths but may also create inequalities between countries, requiring international cooperation to avoid disparities.

## Contribution

The study quantifies how different climate action scenarios affect transboundary air pollution inequalities between developing and developed countries.

## Key findings

- Stricter climate mitigation increases external co-benefits for Africa by +8% in SSP1 and +53% in SSP3.
- Developing countries are more dependent on external climate action for air pollution co-benefits.
- The most ambitious climate scenario avoids 1.32 million deaths but still shows transboundary pollution disparities.

## Abstract

Climate action ameliorates public health by reducing hazardous air pollutants alongside greenhouse gases, yet misguided mitigation efforts could induce imbalances in air pollution exchange across international borders. Despite its potential to endanger equality, the effects from climate action on transboundary air pollution are relatively unstudied. Here we show that stricter mitigation increases the fraction of co-benefits that originate externally in Africa by +8% in shared socioeconomic pathways (SSP) towards sustainability (SSP1) and by +53% for fragmentation (SSP3). The fraction of externally originating co-benefits is greater in developing countries (0.76 in SSP1-26) than developed (0.65), indicating that developing countries are more dependent on external action. Although co-benefits are maximized in the most ambitious scenario, SSP1-19 (1.32 million deaths avoided), their transboundary exchange between countries varies. These results suggest a need for climate policies that consider how inequalities in transboundary air pollution evolve across distinct socioeconomic trends and mitigation strategies in addition to total co-benefit estimates.

Climate action could avoid over 1 million deaths globally from air pollution in 2040. However, it is suggested that cooperation is needed between developed and developing nations to ensure that disparities in air pollution are not perpetuated in the future.