Health Burden from Fine Particles, Black and Organic Carbon, and Ozone in Ambient Air

The long-term exposure to fine particulate matter (PM2.5) and ozone (O3) poses a main public health risk. We used a data-informed global atmospheric model, applying an updated emission inventory and recent disease-specific exposure-response functions to calculate the health burdens of air pollutants from different source categories. We distinguished contributions by black carbon (BC), primary organic aerosols (POA) and anthropogenic secondary organic aerosols (aSOA), making up to 20% of the total PM2.5, e.g. in South and East Asia and East Africa. Epidemiological and toxicological studies indicate that these compounds are several times more harmful than other PM2.5 constituents, related to their high oxidative potential. We estimate 4.23 (95% confidence interval 3.0 6.14) million excess deaths annually from the exposure to ambient PM2.5. We also find that the chronic exposure to PM2.5 contributes significantly to COVID-19 mortality. In addition, we estimate the excess mortality from exposure to O3 at 1.3 (0.93 1.68) million per year. We find that domestic energy use by the burning of solid biofuels is the largest contributor to ambient BC, POA and aSOA globally. Considering these species to be approximately twice as hazardous as other PM2.5 compounds, domestic energy use emerges as the leading cause of mortality attributable to PM2.5, notably in Asia and Africa, and with significant contributions in Europe and America. Further, we find that between 2000 and 2015 excess mortality from ambient PM2.5 and O3 increased by about 30% and 17%, respectively. This is the net result of population aging and growth, in part counterbalanced by advances in health care, which will need to be improved further to prevent mortality increases in future, i.e. concurrently with emission reductions.