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Nouna, situated in the Boucle du Mouhoun region of Burkina Faso (coordinates 12.7333° N, -3.8667° W), occupies a geographically significant position within the West African savanna. The city’s terrain is gently undulating, characterized by reddish-brown lateritic soils typical of the Sahelian zone. Elevation averages around 280 meters above sea level, influencing local air circulation patterns. Nouna is nestled within a transitional landscape, bordering both expansive agricultural lands and drier savanna ecosystems. The surrounding area is predominantly agricultural, with millet, sorghum, and maize cultivation being primary activities, contributing to seasonal dust emissions. While Nouna lacks immediate proximity to major rivers, it benefits from seasonal watercourses that contribute to localized humidity and influence atmospheric stability. The urban–rural gradient around Nouna is relatively sharp; the city acts as a regional market town and administrative center, drawing in rural populations, which contributes to increasing urban density and associated pollution sources. The regional position, acting as a crossroads for trade routes, also brings vehicular traffic. The prevailing winds are generally from the north during the dry season, carrying dust from the Sahara and Sahel, and shifting to a more southerly direction during the rainy season, potentially dispersing pollutants locally. The relatively flat topography, combined with the surrounding agricultural activity, can lead to the accumulation of particulate matter, particularly during periods of low wind speed and temperature inversions.

Nouna’s air quality experiences a distinct seasonal cycle dictated by the region’s tropical savanna climate. The dry season, spanning roughly November to May, presents the most significant air quality challenges. Characterized by minimal rainfall and consistently high temperatures, this period is prone to dust intrusions from the Sahara and Sahel, significantly increasing particulate matter concentrations. Strong, northerly winds frequently transport this dust, reducing visibility and impacting respiratory health. Temperature inversions, common during the cooler nights of the dry season, trap pollutants near the ground, exacerbating the problem. The months of January and February often see the highest levels of dust-related pollution. Conversely, the rainy season (June to October) brings a period of relative improvement. Frequent rainfall effectively washes pollutants from the atmosphere, and increased humidity can help to suppress dust lifting. However, agricultural activities, including burning of crop residues after harvest (typically in late May/early June), can introduce localized plumes of smoke and particulate matter. Fog, particularly in the early mornings during the transition periods between seasons, can also temporarily trap pollutants. 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 events. During the rainy season, while overall air quality improves, vigilance regarding smoke from agricultural burning remains important.