Dispur, the capital of Assam in northeastern India, occupies a distinctive geographic position that profoundly shapes its air quality dynamics. Situated within the Brahmaputra Valley at approximately 55 meters above sea level, the city lies on the southern bank of the mighty Brahmaputra River, which flows just north of the urban core. This low-lying floodplain location creates a basin-like topography where pollutants can accumulate, particularly during calm weather conditions. Dispur forms part of the larger Guwahati metropolitan area, blending administrative functions with residential and commercial zones in a rapidly urbanising landscape. The city is surrounded by the Shillong Plateau to the south and the Himalayan foothills to the north, creating a partial topographic enclosure that can trap air masses. While not part of a major industrial belt, Dispur experiences pollution from vehicular emissions, construction dust, and occasional agricultural burning in surrounding rural areas, especially during post-harvest seasons. The urban-rural gradient is pronounced, with the city transitioning quickly to tea gardens, paddy fields, and forested hills. This proximity to agricultural zones means seasonal biomass burning contributes to particulate matter, while the Brahmaputra's moisture can interact with pollutants to form haze. The combination of valley location, riverine humidity, and increasing urban emissions creates a complex air quality scenario unique to this regional capital.

Dispur's air quality follows a distinct seasonal rhythm shaped by the South Asian monsoon and regional weather patterns. During winter (December-February), cold temperatures and frequent temperature inversions trap pollutants close to the ground, creating persistent haze and fog that mix with vehicular emissions and occasional biomass burning from surrounding agricultural areas. This season typically sees the poorest air quality, with sensitive groups advised to limit outdoor exertion during morning hours when inversions are strongest. Spring (March-May) brings gradually improving conditions as temperatures rise and ventilation increases, though occasional pre-monsoon dust storms can temporarily elevate particulate levels. The summer monsoon (June-September) dramatically cleanses the atmosphere through heavy rainfall and strong southerly winds, making this the optimal period for outdoor activities with consistently good air quality. Autumn (October-November) marks a transitional phase where retreating monsoon winds give way to calmer conditions, allowing pollutants to gradually accumulate again, particularly from post-harvest agricultural burning in the surrounding valley. Throughout the year, the Brahmaputra Valley's topography can create localised pollution pockets, especially during periods of low wind speed. Sensitive individuals should monitor conditions particularly during winter mornings and autumn evenings when pollutant concentrations tend to peak.