Heatwaves amplify air pollution risks in Sub-Saharan Africa
Egide Kalisa1, Andrew Sudmant2
1Department of Epidemiology and Biostatistics, Schulich School of Medicine and Dentistry, Western University, London, ON, N6G 2M1, Canada. ekalisa2@uwo.ca.
Scientific Reports
|July 21, 2025
Summary
Heatwaves significantly worsen urban air pollution, especially ozone, in Kigali, Rwanda. This study reveals compound risks for Sub-Saharan African cities, needing integrated heat and air quality policies.
Area of Science:
- Environmental Science
- Public Health
- Atmospheric Chemistry
Background:
- Heatwaves exacerbate urban air pollution globally.
- Research on heat-health impacts in Sub-Saharan Africa is limited.
- Urban air quality is a growing concern in African cities.
Purpose of the Study:
- To investigate the relationship between heatwaves and air pollutants (PM2.5, NO2, O3) in Kigali, Rwanda.
- To assess the impact of extreme heat events on urban air quality in a Sub-Saharan African context.
- To provide data for developing integrated heat and air pollution management strategies.
Main Methods:
- Utilized low-cost sensors for dense spatiotemporal air quality monitoring (2021-2024).
- Analyzed air pollutant concentrations during 6 identified heatwave events.
- Conducted diurnal and seasonal analyses of PM2.5, NO2, and O3 dynamics.
Main Results:
- Ozone (O3) concentrations significantly increased during heatwaves, peaking up to 40% higher.
- Fine particulate matter (PM2.5) and nitrogen dioxide (NO2) also spiked during heatwaves.
- PM2.5 and NO2 diurnal/seasonal patterns were primarily driven by local emissions, not solely temperature.
Conclusions:
- Heatwaves pose compound risks to public health in Sub-Saharan African cities.
- Findings highlight unique atmospheric dynamics in the region, differing from high-income countries.
- Emphasizes the need for early-warning systems and urban policies addressing both heat and air pollution.
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