Global Health Risk and Inequality Analysis of Achieving National and WHO Ambient PM2.5 Air Quality Standards

Abstract Exposure to elevated levels of air pollution–particularly fine particulate matter (PM2.5)–is one of the leading contributors to premature mortality globally, with much of the burden falling to lower socioeconomic and disadvantaged communities. To improve ambient air quality, many countries, as well as the World Health Organization (WHO), have established standards for ambient air pollutant concentrations, including PM2.5. This study integrates high-resolution (0.01° × 0.01°) ambient PM2.5 concentration fields, exposure-response functions from the Global Burden of Disease (GBD), and the Global Gridded Relative Deprivation Index (GRDI) to assess the global mortality burden and health risk inequality implications of meeting national and WHO PM2.5 standards. In the 94 countries with national PM2.5 standards, compliance is associated with a ∼9% reduction in global annual premature mortality attributed to ambient PM2.5 exposures (from 3.83 million [95% CI: 2.80–4.70 million] to 3.45 million [95% CI: 2.50–4.26 million]) within those countries. Meeting the WHO annual 5 μg m–3 target, which is more stringent than any country’s standard, can offset ∼70% (from 4.17 million [95% CI: 3.03–5.12 million] to 1.28 million [95% CI: 0.88–1.65 million]) of the global annual premature mortality budget attributed to ambient PM2.5 exposures; modeling shows there will still be 1.28 million [95% CI: 0.88–1.65 million] premature mortalities from ambient PM2.5 exposures annually even if the maximum global PM2.5 concentration is 5 μg m–3. PM2.5-attributable mortality and avoided deaths are highest in socioeconomically deprived countries, which also experienced the largest absolute and relative reductions under clean air scenarios. Improving ambient air quality is a complex, multi-scale endeavor; this global assessment demonstrates that achieving national and WHO PM2.5 standards would yield substantial health benefits while revealing major inequalities in where baseline mortality burdens and potential avoided deaths are concentrated.