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Doba, situated in the Logone Oriental region of Chad (8.6600° N, 16.8500° E), occupies a geographically significant position within the Sahelian belt. The city’s terrain is predominantly flat, characteristic of the expansive floodplain of the Logone River, which forms a natural boundary with Cameroon to the south. This riverine setting dictates much of Doba’s urban character, influencing settlement patterns and economic activities. The surrounding landscape is a mosaic of savanna grasslands, dotted with acacia trees and interspersed with agricultural fields – primarily cultivating sorghum, millet, and maize. The urban–rural gradient transitions rapidly from the densely populated core of Doba to the surrounding agricultural zones, where traditional farming practices are prevalent. Elevation is minimal, rarely exceeding 300 meters above sea level, contributing to a relatively stable atmospheric layer, though also potentially exacerbating ground-level pollutant accumulation. While Doba lacks significant industrial belts within its immediate vicinity, its proximity to agricultural areas means that seasonal burning of crop residue, a common practice for land clearing and fertilization, can significantly impact local air quality. The Logone River itself, while a vital resource, can also contribute to air quality issues through the release of organic compounds and occasional algal blooms. The regional climate, hot and semi-arid, further influences atmospheric conditions, impacting pollutant dispersion and persistence. The flat topography and limited natural barriers mean that pollutants can spread relatively easily across the landscape.

Doba’s air quality follows a distinct seasonal pattern dictated by its tropical savanna climate. The wet season, typically spanning from June to September, brings increased rainfall and higher humidity, generally leading to improved air quality as precipitation washes away particulate matter and increased moisture helps trap pollutants. However, intense storms can temporarily stir up dust and debris. The dry season, from October to May, presents a more challenging scenario. As rainfall diminishes, vegetation cover thins, and the risk of wildfires increases dramatically. Agricultural practices, particularly the burning of crop residue after harvest (often in November and December), become a major source of particulate pollution. Temperature inversions, common during the cooler months (December to February), trap pollutants near the ground, leading to periods of stagnant air and potentially elevated concentrations of smoke and dust. Wind patterns are generally light during the dry season, further hindering pollutant dispersal. March to May sees a gradual increase in dust storms originating from the Sahara Desert, carried by prevailing winds, which significantly degrade air quality. Sensitive groups, including children, the elderly, and individuals with respiratory conditions, should exercise caution during the dry season, particularly during periods of agricultural burning and dust storms. Outdoor activities are generally more favourable during the wet season, although vigilance regarding storm conditions is still advised. The transition months (May and October) often experience fluctuating air quality as the climate shifts between dry and wet conditions.