East African City Centers Show Lower PM_2.5 Levels than Their Suburbs

Area of Science:

• Environmental Science
• Atmospheric Science
• Public Health

Background:

• Urban air pollution is a significant issue in developing economies, especially in data-limited areas.
• Effective air quality monitoring is crucial for public health and environmental management.

Purpose of the Study:

• To assess air quality in three major East African cities: Kampala, Nairobi, and Dar es Salaam.
• To develop a scalable method for monitoring air quality in data-scarce regions using integrated sensor and satellite data.

Main Methods:

• Integration of low-cost air sensors with satellite data.
• Generation of daily 1 km x 1 km resolution PM2.5 maps from 2019 to 2023.
• Analysis of PM2.5 concentration variations between urban centers and suburban areas.

Main Results:

• Average PM2.5 concentrations: Kampala (31.4 ± 6.6 μg/m³), Nairobi (21.7 ± 2.8 μg/m³), Dar es Salaam (33.1 ± 7.4 μg/m³).
• Air quality levels ranged from moderate to unhealthy across the studied cities.
• Suburban areas exhibited higher PM2.5 concentrations compared to urban centers.

Conclusions:

• Air quality mitigation strategies must encompass suburban areas, not just urban centers.
• Combustion activities and seasonal vegetation loss in suburbs likely contribute to higher PM2.5 levels.
• The study presents a viable approach for air quality monitoring in data-scarce regions, emphasizing localized management.