Global health burden of PM2.5, black and organic carbon aerosols

Abstract

BACKGROUND AND AIM: Exposure to ambient particulate matter with a diameter smaller than 2.5µm (PM2.5) poses a major global health risk, commonly assessed with exposure-response functions that presume equivalent toxicity for different PM2.5 constituents. In this study, we assume anthropogenic organic aerosols and black carbon to be more health hazardous than other PM2.5 components as indicated by recent epidemiological and toxicological studies. METHODS: We used a data-informed global atmospheric chemistry model and exposure-response functions of the Global Burden of Disease study in 2020 to estimate the health burden of ambient PM2.5, and to attribute source categories. We also calculated the contributions of black carbon (BC), primary organic aerosols (POA) and anthropogenic secondary organic aerosols (aSOA). RESULTS:We estimated 4.23(95% confidence interval 3.0-6.14) million excess deaths per year from exposure to ambient PM2.5 of which, ∼67% may be attributed to anthropogenic sources assuming uniform toxicity for all types of PM2.5. Globally, 92%, 5% and 3% of excess deaths occur among adults, neonates and children, respectively, although these proportions vary largely by region. We find that domestic energy use, mostly from the burning of solid biofuels, is the largest contributor to BC, POA and aSOA globally. Considering these species to be twice as toxic as other compounds, domestic energy use emerges as the leading source of excess mortality from PM2.5 exposure, notably in Asia and Africa but also, in North America and Europe, where fossil fuel use in energy generation and transportation is the largest source category of anthropogenic PM2.5, mitigating emissions from domestic burning would have major health benefits. CONCLUSIONS:We suggest that relative toxicities of anthropogenic PM2.5 components and their sources should be considered in air quality policies. Our results offer a basis for country-specific mitigation measures, which will be more effective in improving air quality and public health than the conventional PM2.5 abatement measures. KEYWORDS: Particulate matter, Particle components, Policy research