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Sunāmganj, situated in the northeastern corner of Bangladesh within the Sylhet Division, occupies a unique position at the nexus of the Surma River basin and the foothills of the Meghalaya plateau. Characterized by its low-lying, flat alluvial terrain, the city serves as a gateway to the vast haor wetlands—a complex system of bowl-shaped depressions that dominate the regional topography. This proximity to expansive aquatic ecosystems significantly influences the city’s microclimate and air quality. During the monsoon, the landscape transforms into a vast inland sea, which helps scrub particulate matter from the atmosphere, providing a natural cleansing mechanism. However, the urban character of Sunāmganj is marked by dense, unplanned development interspersed with agricultural zones. The city acts as a transit point for heavy vehicular traffic moving goods between the Indian border and the interior of Bangladesh. The geographical bottleneck created by the nearby mountainous regions often traps air masses, preventing the efficient dispersion of pollutants. Furthermore, the urban-rural gradient is blurred; the city’s expansion encroaches upon fertile wetlands, leading to increased local dust production from construction activities. The regional air quality is also susceptible to transboundary haze, as the prevailing winds carry emissions from industrial zones located across the border. While the abundance of water bodies offers a cooling effect, the lack of robust green corridors within the city center exacerbates the heat island effect, particularly during the transition months. Consequently, Sunāmganj’s air quality is a delicate balance between natural meteorological cleansing by the monsoon and the anthropogenic pressures of rapid, localized urbanization.

Sunāmganj experiences a distinct tropical monsoon climate that dictates the rhythm of its air quality. The year is defined by the contrast between the wet season and the dry season, with the latter presenting significant atmospheric challenges. From November through February, the post-monsoon and winter months bring stable weather patterns characterized by low wind speeds and frequent temperature inversions. During these months, the cool air near the ground traps particulate matter, smoke from domestic cooking, and vehicular emissions, resulting in persistent haze that settles over the city. Residents should exercise caution during these mornings, as the air remains stagnant until the sun burns off the inversion layer. Conversely, the pre-monsoon period in March and April is marked by sporadic thunderstorms, known locally as Kalbaisakhi, which provide temporary relief by dispersing accumulated pollutants. The true cleansing of the atmosphere arrives with the onset of the monsoon in late May, when heavy, consistent rainfall washes away suspended dust and pollutants, leading to the cleanest air of the year. This period is ideal for outdoor activities, though the high humidity requires attention for those with respiratory sensitivities. As the rains taper off in October, the cycle begins anew. Sensitive groups, including children, the elderly, and those with pre-existing conditions, are advised to monitor local conditions closely during the winter months, opting for indoor exercise when visibility is low or air quality feels heavy. By understanding these seasonal shifts, residents can better navigate the city's environment while prioritizing their long-term health and respiratory well-being.