Unraveling the health impacts of local and cross-border air pollution

Long term exposure to fine particulate matter (PM_2.5) is a major health risk associated with excess mortality. Ambient PM_2.5 concentrations at a given location are subject not only to local pollution but also to that transported from other regions. To unravel the contribution of local and cross-border pollution to the PM_2.5 related excess mortality of each country around the world, numerous simulations are carried out with the chemistry general circulation model EMAC (ECHAM5/MESSy for Atmospheric Chemistry), removing each time the anthropogenic emissions of a country. The simulations are performed at a T106 horizontal resolution (equivalent to 1.1 x 1.1 degree at the equator) for the year 2015, while the anthropogenic emissions of each country are based on CEDS (Community Emissions Data System, 2020-v1). Mortality calculations are performed applying the FUSION exposure-response function, with country-level population and mortality rates obtained from the GBD (Global Burden of Disease). We find that local pollution is the main driver of PM_2.5 related excess mortality in China and India, while cross-border pollution is responsible for at least one out of two excess deaths attributable to PM_2.5 in many European countries. Our results reveal the limits of health-driven mitigation, supporting policy makers to design and implement actions at both national and international levels.