Global urban temporal trends in fine particulate matter and attributable health burdens.

Abstract:

While most air pollution health impact assessments present results at the country, state or county level, studies of city-level air pollutant concentrations and attributable health burdens demonstrate variation of air pollutant concentrations by urban area. With most of the world’s population residing in cities, an understanding of city-level exposures is needed; however, prior studies of urban air pollution have not considered trends in air pollutant concentrations nor corresponding attributable health burdens. In this analysis, we describe temporal trends in population weighted fine particulate matter (PM_2.5) and PM_2.5-attributable health burdens for ~100 cities globally between 1990 and 2019. By employing the Global Burden of Disease (GBD) project concentration estimates and methods using satellite observations of aerosol optical depth, we can provide insight into previously undescribed air pollution trends, particularly in areas for which ground-based monitoring is sparse. Preliminary trend analysis indicates an overall population weighted average of 27 µg/m³ in included global cities, approximately three times the World Health Organization annual average guideline for PM_2.5. We also find that city PM_2.5 levels decreased by 14% on average across these cities, with wide variation in direction and magnitude across the cities. Consistent with prior studies, the largest decreases were seen in North American cities (33%), and largest increases in South and West Africa (14%). By estimating air pollutant concentrations and attributable mortality estimates at the city-level, this analysis can be used by city-level decision-makers to inform city planning and catalyze further action to mitigate air pollution in urban areas.