Socio-demographic factors shaping the future global health burden from air pollution

Exposure to ambient particulate matter (PM_2.5) currently contributes to millions of global premature deaths every year. Here, we assess the pollution and health futures in five 2015–2100 scenarios using an integrated modelling framework. On the basis of a global Earth System Model (GFDL-ESM4.1), we find lower ambient PM_2.5 concentrations, both globally and regionally, in future scenarios that are less fossil fuel-dependent and with more stringent pollution controls. Across the five scenarios, the global cumulative PM_2.5-related deaths vary by a factor of two. However, the projected deaths are not necessarily lower in scenarios with less warming or cleaner air. This is because while reducing PM_2.5 pollution lowers the exposure level, increasing the size of vulnerable populations can significantly increase PM_2.5-related deaths. For most countries, we find that changes in socio-demographic factors (for example, ageing and declining baseline mortality rates) play a more important role than the exposure level in shaping future health burden.