Dhemāji, nestled in the northeastern Indian state of Assam, occupies a geographically significant position within the Brahmaputra River Valley. Located at approximately 27.48°N, 94.58°E, the city’s terrain is predominantly alluvial, a direct consequence of the region’s history of riverine deposition. The elevation is relatively low, averaging around 85 meters above sea level, contributing to a humid subtropical climate and influencing atmospheric stability. Dhemāji is surrounded by a mosaic of landscapes: dense tropical forests to the north and east, agricultural fields dominating the central plains, and the expansive Brahmaputra River forming its southern boundary. This proximity to the river, while providing vital resources, can also exacerbate air quality issues through the transport of pollutants and the formation of ground-level ozone during warmer months. The urban–rural gradient is gradual, with agricultural activities – primarily rice cultivation and tea plantations – significantly impacting the surrounding air quality. While Dhemāji itself is a relatively small town, it serves as a regional hub for the surrounding rural communities. The absence of major heavy industries within the immediate vicinity is a mitigating factor, however, agricultural burning during post-harvest seasons and vehicular emissions from increasing traffic contribute to localized air pollution. The flat topography limits atmospheric dispersion, potentially trapping pollutants, especially during periods of stagnant air. The region's vulnerability to flooding, a recurring phenomenon linked to the monsoon, can also temporarily worsen air quality by stirring up sediment and particulate matter.

Dhemāji’s air quality follows a distinct seasonal pattern dictated by the region’s monsoonal climate. The monsoon season, typically spanning June to September, brings heavy rainfall and strong winds, generally leading to improved air quality as pollutants are washed away and dispersed. However, the preceding pre-monsoon period (March-May) often witnesses a concerning rise in air pollution. This is largely attributable to agricultural burning – farmers clearing crop residue after the harvest – releasing significant quantities of particulate matter and gases. The hot, dry conditions during this period exacerbate the situation, promoting photochemical smog formation. The post-monsoon season (October-November) sees a gradual improvement, but lingering smoke from agricultural practices can still impact air quality. Winter months (December-February) are characterized by cooler temperatures and frequently dense fog, which traps pollutants near the ground, creating conditions conducive to poor air quality. Temperature inversions, common during these cold nights, further impede vertical mixing, concentrating 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. During the monsoon, while overall air quality improves, the risk of waterborne diseases increases, requiring vigilance regarding water safety. Maintaining indoor air quality through proper ventilation and air purification can be beneficial throughout the year, particularly during periods of elevated pollution.