Mangalmé, a town in the Guéra region of Chad, occupies a geographically significant position within the country’s central highlands. Located at coordinates 12.3547°N, 19.6139°E, the town sits at an elevation of approximately 580 meters (1903 feet) above sea level. This altitude contributes to generally cooler temperatures compared to lower-lying areas of Chad, but also influences atmospheric circulation patterns. The surrounding landscape is characterised by undulating savanna grasslands and scattered acacia trees, typical of the Sahelian zone. Mangalmé isn’t proximate to any major bodies of water; the nearest significant water source is likely seasonal streams and *wadis* that fill during the rainy season. The urban character of Mangalmé is largely defined by its role as a regional market centre and administrative hub, with a population of around 11,155. The immediate area is dominated by subsistence agriculture – primarily millet, sorghum, and livestock rearing. This agricultural activity, while vital to the local economy, contributes to particulate matter pollution through land clearing and seasonal burning of crop residue. The urban-rural gradient is relatively sharp, with a rapid transition from the town’s centre to surrounding rural farmland. Dust from unpaved roads and open land is a constant factor, exacerbated by the region’s arid climate and wind patterns, directly impacting local air quality.

Mangalmé experiences a distinct wet and dry season, heavily influencing its air quality. The dry season, spanning roughly November to May, is characterised by consistently high levels of particulate matter. Harmattan winds, originating from the Sahara Desert, carry vast quantities of dust southward, significantly degrading air quality. January to March are typically the worst months, with reduced visibility and increased respiratory irritation. The dry heat also promotes temperature inversions, trapping pollutants near the ground. The onset of the wet season in June brings a temporary improvement. Rainfall washes away accumulated dust, and increased humidity suppresses dust resuspension. However, the wet season isn’t without its challenges. Increased agricultural activity – land preparation and planting – can lead to localised burning of vegetation, releasing smoke and particulate matter. July and August see a peak in biomass burning related to agricultural practices. As the wet season wanes in September and October, dust levels begin to rise again. Sensitive groups – children, the elderly, and those with pre-existing respiratory conditions – should limit outdoor activity during the peak of the dry season and periods of agricultural burning. Monitoring wind direction and avoiding areas downwind of burning is advisable.