For some air pollutants, for example concentrations of PM2.5 in several US, Western European and Chinese cities have recently decreased as a result of clean air regulations that have controlled emissions from sources such as motor vehicles, fossil fuel power plants and major industries . These decreases have brought substantial improvements in public health in settlements within these regions . In South Asia, Southeast Asia and Africa, however, concentrations of other air pollutants, for example tropospheric ozone, oxides of nitrogen and volatile organic compounds are likely to continue to grow and peak by mid-century before they subside due to global urbanisation assumptions embedded in the SSPs . Broadly, future air pollutant emissions are projected to decline globally by 2050 as societies become wealthier and more willing to invest in air pollution controls, but the trajectories vary among pollutants, world regions and scenarios . Whereas cities in East Asia and South Asia currently have large exposure to anthropogenic air pollution, African cities may emerge by 2050 as the most polluted because of growing populations and demand for energy, increased urbanisation and relatively weak regulations to control emissions .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report