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Arzew is a strategic coastal enclave situated in the Oran Province of northwestern Algeria, serving as a critical node in the Mediterranean basin's energy infrastructure. The city is characterized by a stark urban-industrial dichotomy, where residential quarters coexist with one of Africa's most intensive petrochemical complexes. Geographically, Arzew lies on a low-lying coastal plain, with its elevation remaining minimal as it meets the shores of the Mediterranean Sea. This flat terrain allows for the unimpeded movement of maritime breezes, which play a dual role in the city's atmospheric chemistry. While the sea air often provides a vital ventilation mechanism, scrubbing pollutants from the dense industrial belt, the proximity to the coast also creates high humidity levels that can trap particulate matter in a thick, saline haze. To the south and east, the landscape transitions from an industrial wasteland into semi-arid agricultural zones and scrubland, creating a sharp urban-rural gradient. The regional position of Arzew makes it susceptible to the influence of both temperate Mediterranean systems and the oppressive heat of the Sahara to the south. The concentration of refineries and liquified natural gas plants creates a localized pollution dome, where emissions of sulfur dioxide and nitrogen oxides are concentrated. Consequently, the city's geography acts as a conduit for industrial effluent, which is periodically dispersed or trapped depending on the prevailing wind directions and the interaction between the cool sea and warm land masses here.

Air quality in Arzew follows a cyclical pattern dictated by Mediterranean meteorology and industrial constancy. During the winter months, the city often experiences temperature inversions, where a layer of warm air traps cooler, pollutant-heavy air near the ground. This phenomenon leads to peaks in smog, particularly during December and January, making it a period where sensitive groups, such as asthmatics, should limit prolonged outdoor exertion. Spring brings a volatile transition; while rainfall helps wash the atmosphere, the arrival of the Sirocco—a hot, dry wind from the Sahara—injects massive quantities of mineral dust into the air. These dust events can spike particulate levels, necessitating the use of masks for vulnerable populations. Summer is characterized by intense solar radiation, which catalyzes the reaction between nitrogen oxides and volatile organic compounds from the refineries, producing ground-level ozone. This photochemical smog is most prevalent in July and August, often coinciding with stagnant air masses that hinder dispersion. Autumn generally provides the most favorable air quality, as the cooling temperatures and returning moisture stabilize the atmosphere and reduce ozone formation. For residents and visitors, the window between September and November offers the healthiest conditions for outdoor activities. Health guidance for Arzew emphasizes monitoring wind direction; when winds blow from the industrial zone toward the residential center, the risk of respiratory irritation increases. Consequently, timing outdoor activities to coincide with strong offshore breezes is the most effective strategy for minimizing exposure.