Ekpé, nestled within the Ouémé State of Benin (coordinates 6.4000, 2.5333) and home to approximately 75,313 residents, occupies a geographically significant position within the coastal plains of West Africa. The city’s terrain is predominantly flat, characteristic of the low-lying coastal region, with gentle undulations towards the interior. This flatness, while facilitating urban expansion, also contributes to air quality challenges as it limits natural dispersion of pollutants. Ekpé lies relatively close to the Atlantic Ocean, approximately 20 kilometers inland, influencing local weather patterns and humidity levels, which can trap pollutants under certain atmospheric conditions. The surrounding landscape is a mosaic of small-scale agriculture – primarily cassava, maize, and vegetables – interspersed with palm groves and scattered settlements. This agricultural activity, while vital to the local economy, can contribute to particulate matter pollution, particularly during harvesting and burning seasons. To the north, the urban–rural gradient gradually transitions into more densely forested areas, offering some degree of natural filtration. There are no major industrial belts immediately adjacent to Ekpé, but the city serves as a regional market town, experiencing significant vehicular traffic from surrounding villages and towns. The proximity to Cotonou, Benin’s economic capital and a major port city, means Ekpé is indirectly affected by industrial emissions and port-related pollution transported by prevailing winds. The flat topography and coastal location combine to create conditions where stagnant air masses can readily form, exacerbating air quality issues.

Ekpé’s tropical climate dictates a distinct wet and dry season cycle, profoundly impacting its air quality. The dry season, typically spanning from November to March, presents the most significant air quality concerns. Reduced rainfall and lower humidity lead to a decrease in atmospheric moisture, hindering the natural cleansing effect of precipitation. Furthermore, the lack of cloud cover allows for increased solar radiation, promoting photochemical reactions that can form ground-level ozone, a respiratory irritant. Wind patterns during this period are often light and variable, leading to stagnant air conditions and pollutant accumulation, especially in the city center. Dust from agricultural activities, particularly land clearing and controlled burns, also contributes significantly to particulate matter levels. The wet season, from April to October, generally brings improved air quality due to frequent rainfall that washes pollutants from the atmosphere. However, periods of intense rainfall can lead to flooding, which can stir up dust and mold spores, temporarily degrading air quality. Fog, a relatively infrequent occurrence, can also trap pollutants close to the ground, creating localized air quality hotspots. During the transition months (March and October), fluctuating weather patterns can result in unpredictable air quality. Sensitive groups, including children, the elderly, and individuals with respiratory conditions, should exercise caution during the dry season, limiting outdoor exertion during peak sunlight hours and avoiding areas with visible smoke. Maintaining indoor air quality through ventilation and air purification can also be beneficial.