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Abéché, the former capital of Ouaddaï province in eastern Chad, occupies a geographically challenging position within the Sahelian zone. Situated at coordinates 13.8331° N, 20.8347° E, the city rests on a relatively high plateau, approximately 550 meters above sea level. This elevation moderates temperatures somewhat, but doesn’t negate the harsh, arid climate. The surrounding landscape is predominantly semi-desert, characterized by sparse vegetation, sandy soils, and rocky outcrops. Abéché isn’t proximate to any significant bodies of water; the nearest substantial water source is Lake Chad, located several hundred kilometers to the west. The urban area itself is expanding, transitioning from a traditional trading post to a more modern, albeit rapidly developing, city. This growth is accompanied by increasing vehicle traffic and localized dust generation from construction. The urban-rural gradient is stark; immediately surrounding Abéché are agricultural lands, primarily subsistence farming, and pastoral areas. Dust from agricultural practices and livestock contributes significantly to particulate matter in the air. The city’s location within a natural dust corridor, coupled with limited infrastructure for dust suppression, exacerbates air quality concerns. The prevailing winds, often originating from the Sahara Desert, carry substantial amounts of dust and sand, impacting air quality throughout the year.

Abéché experiences a distinct bi-seasonal pattern dictated by the movement of the Intertropical Convergence Zone. The wet season, roughly from June to September, brings temporary relief from dust, as rainfall suppresses airborne particles. However, increased humidity can also foster mold growth, potentially impacting respiratory health. October and November mark a transitional period with moderate temperatures and improving air quality. The dry season, spanning December to May, is when air quality deteriorates most significantly. Harmattan winds, originating from the Sahara, dominate during these months, carrying vast quantities of fine particulate matter (PM10 and PM2.5). January to March are particularly challenging, with consistently high dust levels. Temperature inversions, common during cooler nights, trap pollutants near the ground, further worsening conditions. February and March are months to avoid strenuous outdoor activity, especially for those with pre-existing respiratory conditions. Sensitive groups – children, the elderly, and individuals with asthma – should limit exposure during peak dust periods. The relatively high elevation offers some dispersion, but the lack of significant rainfall during the dry season means pollutants accumulate. Monitoring wind direction and staying indoors during dust storms are crucial preventative measures.