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Dehdasht, nestled within the Zagros Mountains of Kohgīlūyeh va Boyer-Ahmad Province, Iran, occupies a geographically complex and challenging position. Located at approximately 30.7964° N, 50.5658° E and an elevation of around 1,800 meters (5,900 feet), the city’s terrain is dominated by steep slopes and deep valleys, characteristic of the mountainous region. The surrounding landscape is a mosaic of rugged peaks, terraced farmlands, and scattered villages, reflecting a long history of agricultural adaptation to the difficult environment. The Dez River, a vital waterway, flows through the city, providing a crucial source of irrigation and influencing local microclimates. Dehdasht sits on the edge of a significant urban–rural gradient; while it serves as a regional hub for the surrounding agricultural communities, it’s not directly adjacent to a major industrial belt. However, the prevalence of small-scale agricultural practices, including burning of crop residues after harvest, and the use of older vehicle fleets contribute to localized pollution. The city’s location within a rain shadow area, influenced by the Zagros range blocking moisture from the west, results in relatively low precipitation. This aridity, combined with the mountainous topography, can trap pollutants, particularly during periods of temperature inversion. The surrounding areas are primarily agricultural, with orchards and cultivated fields, which can contribute to seasonal particulate matter from farming activities. The city’s layout reflects the constraints of the terrain, with buildings often clinging to slopes, further complicating ventilation patterns.

Dehdasht’s air quality experiences a distinct seasonal cycle heavily influenced by meteorological conditions and agricultural practices. The warmer months, typically from May to September, often see increased particulate matter concentrations due to agricultural burning. Farmers traditionally clear fields after harvest by burning crop residues, releasing significant amounts of smoke and pollutants into the atmosphere. This practice, while culturally ingrained, poses a considerable challenge to air quality. During these months, stagnant air conditions, particularly during periods of high pressure, can exacerbate the problem, trapping pollutants close to the ground. Conversely, the cooler months (October to April) generally bring improved air quality, although temperature inversions, common in mountainous regions, can occasionally trap pollutants during calm, clear nights. These inversions occur when a layer of warm air sits above a layer of cold air, preventing vertical mixing and trapping pollutants near the surface. Fog, which can form during the colder months, also contributes to reduced visibility and can temporarily worsen air quality. Spring (April-May) and Autumn (September-October) represent transitional periods with generally moderate air quality. Sensitive groups, including children, the elderly, and individuals with respiratory conditions, should exercise caution during the burning season (May-September) and be mindful of potential inversions during the colder months. Outdoor activities are generally more favorable during the cooler, windier periods, but vigilance is always advised.