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Sfax, Tunisia's second-largest city, occupies a strategic coastal position on the Gulf of Gabès in eastern Tunisia, where the Mediterranean Sea meets the arid Sahel region. The city's geography creates a distinctive urban character as both a major port and industrial hub, with its urban fabric sprawling across a flat coastal plain at an average elevation of just 5 meters above sea level. This low-lying terrain, combined with proximity to the sea, influences air quality through frequent sea breezes that can disperse pollutants but also trap them when atmospheric conditions stagnate. Sfax is surrounded by extensive olive groves that dominate the agricultural landscape, particularly to the west and south, creating an urban-rural gradient where agricultural emissions from olive oil processing blend with urban pollution sources. The city's industrial belt, concentrated along the coastline and port areas, includes phosphate processing, chemical plants, and manufacturing facilities that contribute significantly to emissions. To the east lies the Mediterranean, whose moderating influence on temperature is offset by the city's position downwind of industrial zones when winds blow from the northwest. The flat topography prevents natural ventilation that mountainous regions might provide, allowing pollutants to accumulate during calm weather. Sfax's regional position as a transportation nexus—with major roads connecting it to Tunis and Libya—intensifies vehicle emissions, while construction dust from ongoing urban expansion adds to particulate matter. The surrounding arid landscape contributes road dust that becomes airborne, particularly during dry periods and Sirocco wind events from the Sahara.

Sfax experiences distinct seasonal air quality patterns driven by its Mediterranean climate and local emission sources. During autumn (September-November), air quality begins deteriorating as olive harvest and processing commence, releasing organic compounds and particulate matter from thousands of small-scale mills. This pollution intensifies through winter (December-February), the peak pollution season when temperature inversions trap emissions close to the ground, compounded by increased heating needs and stable atmospheric conditions. The winter months see the worst air quality, particularly during calm periods when Sirocco winds from the south bring Sahara dust that mixes with urban pollution. Sensitive groups should minimize outdoor activities from November through January, especially on days with visible haze or during Sirocco events. Spring (March-May) brings gradual improvement as processing activities wind down and increased rainfall helps clear particulate matter, though construction dust may increase with drier spells. Summer (June-August) offers the best air quality despite extreme heat, as stronger sea breezes disperse pollutants and industrial activity often slows, though ozone levels can rise during heatwaves. The seasonal interplay of agricultural emissions, industrial activity, and meteorological factors creates a predictable annual cycle where late autumn through mid-winter presents the greatest respiratory risks, while late spring through early autumn provides relatively cleaner air for outdoor activities.