Katagon, a small city nestled within the Ouémé Department of Benin, occupies a relatively flat terrain at approximately 6.6333°N latitude and 2.5833°E longitude. Its location is characteristic of the coastal plains of southern Benin, a region dominated by sedimentary soils and a humid equatorial climate. The city’s position is inland, roughly equidistant between the Atlantic coastline and the broader plateau regions further north. This inland location, while offering some protection from direct coastal winds and saltwater intrusion, also means Katagon is less flushed by oceanic breezes that could disperse pollutants. The surrounding landscape is primarily agricultural, dominated by smallholder farms cultivating crops like maize, cassava, and vegetables. The Ouémé River, a vital waterway for Benin, flows nearby, influencing local humidity and potentially contributing to localised fog formation. While Katagon isn’t a major industrial hub, the presence of small-scale processing facilities for agricultural products, alongside residential wood-burning for cooking, contributes to baseline particulate matter levels. The urban-rural gradient is sharp; the city quickly transitions into rural farmland, meaning pollutant dispersion is limited by the lack of significant vegetation buffers. This geographical setting concentrates emissions, impacting local air quality.

Katagon experiences a distinct tropical climate with alternating wet and dry seasons, profoundly influencing air quality. The dry season, typically from November to March, sees a peak in particulate matter pollution. Reduced rainfall means less atmospheric cleansing, and increased dust from agricultural activities and unpaved roads becomes prevalent. Harmattan winds, blowing from the Sahara, can exacerbate this, carrying fine dust particles southward. Temperature inversions, common during the cooler nights of the dry season, trap pollutants near ground level. The wet season, from April to October, generally brings improved air quality due to rainfall washing away pollutants. However, high humidity can also foster mould growth, impacting respiratory health. August and September, the peak of the rainy season, offer the most favourable conditions for outdoor activity. During the transition periods – November and April – air quality is often unpredictable, fluctuating between dry and wet season patterns. Sensitive groups, including children, the elderly, and those with respiratory conditions, should limit strenuous outdoor activity during the dry season and monitor their health closely. Increased ventilation indoors is advisable during both seasons, but particularly during periods of high humidity.