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Vili, nestled within the Centre-Ouest region of Burkina Faso at coordinates 12.2833° N, -2.2167° W, presents a compelling case study in urban geography and its influence on air quality. The city’s location, with a modest elevation, sits within a transitional zone between the Sudanese savanna to the north and the Guinean woodlands to the south. This dictates a landscape characterized by gently undulating plains punctuated by sparse vegetation and scattered acacia trees. The surrounding terrain is predominantly agricultural, with extensive millet and sorghum fields dominating the rural areas immediately bordering Vili, contributing to seasonal dust emissions. While Vili lacks direct proximity to major rivers or lakes, it draws water from boreholes and seasonal streams, impacting local humidity and potentially influencing atmospheric stability. The urban–rural gradient is relatively sharp; the city’s footprint is compact, with a clear delineation between the built environment and the agricultural lands. There are no significant industrial belts immediately adjacent to Vili, though regional markets and small-scale processing activities within the city itself contribute to localized pollution sources. The prevailing winds, generally from the south-east during much of the year, transport dust and pollutants from the surrounding savanna and agricultural zones into the city. The relatively flat topography limits dispersion, and the lack of significant topographic barriers can exacerbate the accumulation of pollutants, particularly during periods of stagnant air. The Sahelian climate, with its distinct dry and wet seasons, further shapes the city’s air quality profile.

Vili’s air quality experiences a pronounced seasonal cycle dictated by its tropical savanna climate. The dry season, typically spanning from November to May, presents the most significant air quality challenges. Characterized by minimal rainfall and high temperatures, this period is prone to intense dust storms originating from the surrounding Sahelian plains. These storms, driven by strong winds, dramatically increase particulate matter concentrations, impacting visibility and respiratory health. Temperature inversions, common during the cooler nights of the dry season, trap pollutants near the ground, further worsening conditions. The months of February and March often see the highest levels of dust-related pollution. Conversely, the wet season (June to October) brings a period of relative improvement. Rainfall effectively ‘washes’ pollutants from the atmosphere, and increased humidity can help to suppress dust emissions. However, the onset of the monsoon season can also bring localized flooding, potentially releasing pollutants from stagnant water sources. Fog, though infrequent, can occur during the transitional periods between seasons, trapping pollutants and reducing air quality. Sensitive groups, including children, the elderly, and individuals with pre-existing respiratory conditions, should exercise caution during the dry season, limiting outdoor activity during peak dust storm periods. During the wet season, while generally better, vigilance regarding potential waterborne pollutants is advised. Maintaining indoor air quality through proper ventilation and filtration is crucial year-round, particularly during periods of elevated dust or humidity.