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Mānikganj, situated in the Dhaka Division of Bangladesh, occupies a geographically significant position within the Bengal Delta. Located approximately 35 kilometers northwest of Dhaka, the nation's capital, it lies on the banks of the Ichamati River, a vital waterway historically and presently influencing the region's hydrology and sediment deposition. The terrain is predominantly alluvial, characteristic of the deltaic plains, resulting in generally flat land with minimal elevation changes – the average elevation is around 12 meters above sea level. This low-lying topography contributes to poor air circulation, particularly during periods of stagnant weather. The surrounding landscape is a mosaic of agricultural fields, primarily rice paddies and jute cultivation, interspersed with small villages and scattered industrial units. Mānikganj’s proximity to the industrial belt surrounding Dhaka, though not directly within it, means it is susceptible to pollutants transported by prevailing winds. The urban–rural gradient is gradual; the city itself is relatively small, transitioning quickly into agricultural land. The Ichamati River, while providing a source of water and transportation, also carries pollutants from upstream sources, potentially impacting local air quality through aerosol deposition. The deltaic nature of the region means the soil is often fine-grained, easily becoming airborne and contributing to particulate matter pollution, especially during the dry season when wind speeds increase. The flat terrain and riverine influence create a unique microclimate that can trap pollutants, exacerbating air quality challenges.

Mānikganj’s air quality experiences a distinct seasonal cycle dictated by the monsoon climate. The monsoon season, typically spanning June to October, brings heavy rainfall and increased humidity, generally leading to a temporary reduction in particulate matter concentrations as rain washes pollutants from the atmosphere. However, flooding events can release methane and other gases from inundated agricultural lands, impacting air quality. The pre-monsoon season (March-May) is often the most challenging period. Rising temperatures and decreasing rainfall create stable atmospheric conditions, frequently leading to temperature inversions where cooler air is trapped beneath a layer of warmer air. This inversion prevents vertical mixing, trapping pollutants near the ground. Agricultural burning, a common practice to clear fields for planting, significantly contributes to smoke and particulate matter during this time. The dry winter months (November-February) are characterized by cooler temperatures and frequent fog, which further restricts air movement and concentrates pollutants. While temperatures are lower, the lack of rainfall and stagnant air conditions can lead to elevated levels of pollutants. Sensitive groups, including children, the elderly, and individuals with respiratory conditions, should exercise caution during the pre-monsoon and winter months, limiting outdoor activities during peak pollution periods. Maintaining indoor air quality through ventilation and air purifiers is also advisable. The post-monsoon period sees a gradual improvement as winds pick up and agricultural burning decreases, but lingering effects from previous pollution episodes can persist.