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Medjana, nestled within the Bordj Bou Arréridj province of Algeria, occupies a strategically significant position at approximately 36.1333° latitude and 4.6667° longitude. The city’s geography is dominated by its location on the foothills of the Aurès Mountains, a range known for its rugged terrain and diverse microclimates. This elevation, averaging around 1100 meters above sea level, contributes to cooler temperatures compared to lower-lying Algerian cities, but also creates conditions conducive to temperature inversions, a key factor influencing air quality. The surrounding landscape is a blend of semi-arid scrubland and terraced agricultural fields, primarily cultivating cereals and olives. The urban–rural gradient transitions relatively quickly, with small villages and agricultural plots bordering the city limits. While Medjana lacks direct proximity to major bodies of water, the nearby Chelif River, though intermittent, influences local humidity and weather patterns. The region’s industrial activity is relatively limited compared to coastal hubs like Algiers, but there are small-scale workshops and agricultural processing facilities within the province. The Aurès Mountains act as a partial barrier, influencing wind patterns and potentially trapping pollutants within the Medjana basin during periods of low wind speed. The topography, combined with the prevailing north-easterly winds, dictates the dispersal of any emissions, making the valley floor particularly susceptible to localized air quality challenges. The city’s compact urban form, while promoting walkability, can also concentrate pollution sources.

Medjana’s air quality experiences a distinct seasonal cycle dictated by its Mediterranean climate and the surrounding topography. The dry, hot summers (June-August) often see stagnant air conditions, particularly during heatwaves. High temperatures suppress convective mixing, leading to temperature inversions where a layer of warm air traps cooler air and pollutants near the ground. This phenomenon is exacerbated by the city’s location within the Aurès foothills, which can create localized basins where pollutants accumulate. Dust storms, common in North Africa, can also significantly degrade air quality during these months, carrying particulate matter from the Sahara. Autumn (September-November) brings a gradual improvement as temperatures cool and wind speeds increase, aiding in pollutant dispersal. Winter (December-February) is generally the most favourable period for air quality, with more frequent rainfall washing away particulate matter and stronger winds facilitating ventilation. However, cold, calm nights can still lead to localized pollution episodes. Spring (March-May) sees a resurgence of dust events and increasing temperatures, gradually returning conditions towards the summer pattern. Sensitive groups, including children, the elderly, and individuals with respiratory conditions, should exercise caution during the summer months, limiting outdoor activity during peak heat and dust storm events. Maintaining indoor air quality through ventilation and air purification can also be beneficial. The agricultural cycle, with burning of crop residues in the surrounding areas, can also contribute to localized pollution spikes during the transition periods between seasons.