Integration of satellites and low-cost sensors for high-resolution air quality mapping in East African megacities

In East Africa, scarcity of air quality data in rapidly expanding cities has hindered planners’ ability to mitigate air pollution effectively. We explored how low-cost air quality sensors, reference monitors, and satellite-derived products from Sentinel-5p and MODIS can be integrated to generate ground-truthed, high-resolution (1 km × 1 km) daily maps of PM_2.5 concentrations over the megacities of Kampala, Nairobi, and Dar es Salaam. These maps and accompanying codes, which in principle can be applied to other data-scarce cities, would be made available during the session. The findings reveal that average PM_2.5 concentrations sometimes exceed recommended air quality thresholds, with significant seasonal and spatial variability. Challenging existing preconceptions, the study found that PM_2.5 levels could be higher in suburban zones than in city centres, due to seasonal vegetation shifts and combustion-related activities. This work further demonstrates the feasibility of combining low-cost sensors with satellite data to improve air quality monitoring especially in data-scarce regions.