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Ouattagouna, nestled within the Gao Region of Mali, occupies a geographically significant position on the edge of the Inner Niger Delta, a vital floodplain ecosystem. Located at approximately 15.1786° N, 0.7239° E, the city’s terrain is predominantly flat, characteristic of the Sahelian landscape. Its elevation is minimal, hovering around 220 meters above sea level, contributing to a low dispersion potential for airborne pollutants. The surrounding landscape is a mosaic of semi-arid grasslands, sparse acacia woodlands, and the seasonally inundated floodplains of the Niger River. This proximity to the river, while providing crucial water resources, also introduces a unique set of challenges. During the flood season, stagnant water can exacerbate humidity and contribute to the formation of ground-level ozone, a secondary pollutant. The urban–rural gradient transitions rapidly, with agricultural zones – primarily millet and sorghum cultivation – dominating the immediate periphery. Further afield, the landscape gradually shifts to more extensive savannah. There are no major industrial belts directly adjacent to Ouattagouna, however, the city serves as a regional trading hub, with vehicular traffic contributing to localized pollution. The delta’s complex hydrological system, coupled with the flat topography, creates conditions where pollutants can linger, particularly during periods of reduced wind activity. The prevailing Harmattan winds, though generally beneficial for dispersion, can occasionally stall, trapping pollutants within the local basin. The city’s location within the broader Sahelian zone means it is highly susceptible to desertification processes, which can contribute to dust storms and particulate matter pollution.

Ouattagouna’s air quality is inextricably linked to its distinct wet and dry seasons. The dry season, typically spanning November to May, presents the most significant air quality challenges. Characterized by intense solar radiation, low humidity, and frequent Harmattan winds, this period often sees elevated levels of particulate matter, particularly dust originating from the Sahara Desert and local agricultural activities. Temperature inversions, common during the cooler nights of December and January, trap pollutants close to the ground, worsening conditions. The Harmattan, while usually a cleansing wind, can sometimes weaken, allowing dust to accumulate. February and March are often the most problematic months, with increased agricultural burning contributing to smoke pollution. The wet season, from June to October, brings a relative improvement in air quality due to increased rainfall, which washes pollutants from the atmosphere and higher humidity which reduces dust lift. However, the monsoon season can also bring localized flooding, leading to increased mould and fungal spores, impacting respiratory health. Fog, though infrequent, can occur during the transition periods, trapping pollutants and reducing visibility. Sensitive groups, including children, the elderly, and individuals with pre-existing respiratory conditions, should limit outdoor activity during the dry season, particularly during dust storm events. Agricultural workers should take precautions against smoke inhalation during burning periods. Maintaining indoor air quality through ventilation and air filtration is recommended throughout the year, but especially during the dry season.