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Sagala, nestled within the Koulikoro Region of Mali, occupies a geographically significant position on the edge of the Sahel, a transitional zone between the Sahara Desert and the Sudanian Savanna. Located at approximately 14.1103° latitude and -7.8881° longitude, the city’s terrain is predominantly flat, characteristic of the surrounding inland Niger River floodplain. The elevation is relatively low, contributing to a tendency for pollutants to accumulate, particularly during periods of atmospheric stability. Sagala’s proximity to the Niger River, while providing a vital water source and supporting agricultural activities, also influences local weather patterns and can exacerbate humidity, impacting the dispersion of airborne particles. The surrounding landscape is dominated by agricultural land – primarily millet, sorghum, and maize cultivation – interspersed with acacia woodlands and grasslands. This agricultural zone, while crucial for regional food security, can be a source of particulate matter from agricultural burning practices, especially during the dry season. The urban–rural gradient around Sagala is gradual, with small villages and agricultural plots extending outwards, creating a diffuse pattern of human activity. There are no major industrial belts immediately adjacent to Sagala, but regional trade routes pass through, potentially introducing pollutants from vehicles. The city’s location within the Sahel means it experiences a semi-arid climate, with limited rainfall and high temperatures, factors that influence atmospheric mixing and the persistence of pollutants. The flat topography and limited natural barriers hinder the effective dispersal of air contaminants.

Sagala’s air quality follows a distinct seasonal pattern dictated by its semi-arid climate. The dry season, spanning roughly from November to May, presents the most significant air quality challenges. During these months, reduced rainfall and consistently high temperatures lead to lower atmospheric humidity, inhibiting the natural cleansing effect of precipitation. Wind speeds are often lower during this period, fostering stagnant air conditions and promoting the build-up of pollutants. Agricultural burning, a common practice for land clearing and residue disposal, intensifies during the dry season, releasing substantial amounts of particulate matter and contributing to hazy conditions. Temperature inversions, where a layer of warm air traps cooler air near the ground, are also more frequent, further hindering vertical mixing and concentrating pollutants. The months of January and February are particularly concerning due to the combination of agricultural burning and stable atmospheric conditions. The wet season, from June to October, brings relief as rainfall washes away accumulated pollutants and increased humidity aids in their dispersion. However, periods of intense rainfall can also lead to increased dust resuspension, temporarily degrading air quality. Fog, though infrequent, can occur during the transition periods, trapping pollutants close to the ground. Sensitive groups, including children, the elderly, and individuals with respiratory conditions, should exercise caution during the dry season, limiting outdoor activities during peak burning periods and seeking shelter when air quality is visibly poor. Maintaining indoor air quality through ventilation and air filtration is also advisable.