Air quality and attributable mortality among city dwellers in Kampala, Uganda: results from 4 years of continuous PM_2.5 concentration monitoring using BAM 1022 reference instrument

Background: Ambient air pollution is a known risk factor for non-communicable diseases and premature mortality. Kampala’s rapid urban growth, biomass and solid waste burning, unpaved roads, and a growing, highly polluting vehicle fleet contribute to poor air quality. Objective: To provide evidence-based estimates of mortality attributable to ambient fine particulate matter (PM2.5) in Kampala. Methods: A time-series design used hourly PM2.5 data (µg/m3) from a Beta Attenuation Monitor (BAM-1022) on the Makerere University School of Public Health rooftop (2018–2021). All-cause (non-accidental) mortality data were obtained from the Uganda Bureau of Statistics and Ministry of Health. The WHO AirQ+ tool was used to estimate attributable mortality relative to WHO guideline and interim targets. Results: The 4-year annual average PM2.5 concentration was 39 µg/m3, with lower levels in rainy seasons. PM2.5 peaks occurred around 09:00 and 21:00, likely reflecting traffic and meteorology; Saturdays had the highest daily average (41.2 µg/m3). Attributable mortality to long-term exposure (above WHO annual guideline of 5 µg/m3) was estimated as 2777 (19.3%), 2136 (17.9%), 1281 (17.9%), and 1063 (19.8%) deaths for 2018–2021, respectively; totaling 7257 deaths over four years. Impact: This first Kampala-specific estimate using WHO’s 5 µg/m3 target shows PM2.5 levels far above guidelines with substantial health impacts, underscoring the need for air quality control measures.

Lynn M. Atuyambe, Samuel Etajak, Felix Walyawula, Simon Kasasa, Agnes Nyabigambo, William Bazeyo, Heather Wipfli, Jonathan M. Samet, Kiros T. Berhane