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Situated within the Ségou Region of Mali, Dyero occupies a strategic position in the vast, semi-arid landscape of the Sahel. The terrain is characterized by flat, expansive plains that transition into the fertile floodplains of the Niger River basin. This geography is defined by a low-relief landscape where the elevation remains relatively consistent, providing little topographic obstruction to regional wind patterns. The urban character of Dyero is intrinsically linked to its agricultural surroundings, where traditional subsistence farming and livestock grazing create an urban-rural gradient that is porous and heavily influenced by seasonal land-use changes. Because the city lies in a semi-arid zone, the soil composition is primarily composed of fine, loose silts and clays that become highly susceptible to wind erosion during the dry months. The proximity to the Niger River creates a localized microclimate, yet it is the vast, open savannah surrounding the city that dictates its air quality profile. During the dry season, the lack of vegetation cover allows for significant dust mobilization, which is exacerbated by the harmattan winds blowing from the Sahara. There are no major industrial belts in the immediate vicinity; however, the combustion of biomass for domestic cooking and the burning of agricultural waste on the periphery contribute significantly to the local aerosol load. The absence of dense urban forest canopies means that there is limited natural filtration for these airborne particles, making the city’s air quality sensitive to the regional shifts in atmospheric pressure and the seasonal movement of the Intertropical Convergence Zone.

Dyero experiences a distinct climatic cycle defined by the alternation between the dry harmattan season and the humid monsoon period. From November to March, the harmattan winds arrive from the northeast, bringing dry, dusty air from the Sahara. This period represents the most challenging time for air quality, as fine particulate matter is suspended in the atmosphere for weeks, creating a hazy, overcast horizon. Temperature inversions are common during these cool, clear nights, trapping smoke from domestic fires near the ground, which can exacerbate respiratory discomfort for sensitive groups. Health guidance during these months suggests minimizing strenuous outdoor activity during the early morning hours when these inversions are most stable. As the season transitions into April and May, temperatures spike, and the air becomes stagnant before the onset of the rains. The arrival of the West African Monsoon in June brings a welcome shift; the moisture-laden winds from the Gulf of Guinea effectively scrub the atmosphere of dust and smoke. Throughout the wet season, which lasts until October, air quality is at its best, characterized by high humidity and frequent precipitation that washes pollutants from the air. Residents should favor these months for outdoor exercise. However, as the rains taper off in late October, the cycle begins anew. Sensitive individuals, particularly those with asthma or chronic lung conditions, should remain vigilant during the transition periods of October and November, as the shift from wet to dry conditions often coincides with agricultural burning practices that degrade air quality significantly.