Kassa, a small town situated within the Mopti Region of Mali, occupies a geographically significant position in the inland delta of the Niger River. Located at approximately 14.7247° latitude and -3.0664° longitude, its terrain is predominantly flat, characteristic of the Sahelian zone. The surrounding landscape is a mosaic of floodplains, savannas, and agricultural fields, reflecting the region’s reliance on riverine and rain-fed agriculture. The Niger River, though not directly adjacent to Kassa, exerts a profound influence on the local climate and hydrology, contributing to seasonal flooding and high humidity. The town’s proximity to the river also means it’s part of a wider network of waterways and wetlands, supporting a rich biodiversity. Kassa’s urban character is that of a small, rural settlement, with limited industrial activity. The dominant land use is residential and agricultural, with a gradual urban–rural gradient extending outwards into the surrounding savanna. There are no major industrial belts nearby; however, agricultural practices, particularly burning of vegetation after harvest, can contribute to localized air pollution. The elevation is low, generally below 200 meters above sea level, which can exacerbate temperature inversions during the cooler months, trapping pollutants near the ground. The regional position within the Sahel means Kassa experiences a semi-arid climate, with distinct wet and dry seasons, impacting both the landscape and the potential for dust and particulate matter to become airborne. The flat topography limits natural ventilation, potentially hindering the dispersion of pollutants.

Kassa’s air quality follows a distinct seasonal pattern dictated by its Sahelian climate. The wet season, typically from June to September, brings relief from dust and particulate matter as rainfall washes pollutants from the atmosphere and vegetation growth increases, acting as a natural filter. However, increased humidity can exacerbate respiratory issues for sensitive individuals. The dry season, spanning from October to May, presents a more challenging air quality scenario. Wind speeds increase, often carrying fine dust particles from the surrounding savanna and agricultural lands. During the cooler months (November to February), temperature inversions are more frequent, trapping pollutants close to the ground, particularly in the mornings. Agricultural burning, a common practice after the harvest, significantly contributes to localized smoke and particulate pollution during this period. March to May sees a gradual increase in dust storms as the dry season intensifies, with winds picking up loose soil. The transition months (May and October) are generally characterized by moderate air quality, with fluctuating conditions as the climate shifts between wet and dry. Sensitive groups, including children, the elderly, and those with pre-existing respiratory conditions, should exercise caution during the dry season, particularly during periods of agricultural burning or dust storms. Avoiding strenuous outdoor activity during peak pollution times, such as early mornings in the cooler months, is advisable. Staying indoors with filtered air when possible can also mitigate exposure.