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Guwāhāti, the largest city in Assam and northeastern India's principal urban hub, occupies a strategic position on the southern bank of the Brahmaputra River, with coordinates at 26.1722°N, 91.7458°E. This sprawling metropolis, with a population exceeding 1.1 million, sits at a modest elevation of approximately 55 meters above sea level, nestled within the Brahmaputra Valley—a vast floodplain flanked by the Shillong Plateau to the south and the Himalayan foothills to the north. The city's geography profoundly influences its air quality through a combination of natural and anthropogenic factors. Guwāhāti's urban character blends dense commercial districts with residential sprawl, extending into peri-urban and rural zones where agriculture, particularly tea plantations and paddy fields, dominates the landscape. Proximity to the Brahmaputra River, while providing a natural corridor, contributes to high humidity levels that can trap pollutants, especially during calm weather conditions. The city lies within an emerging industrial belt, with nearby areas hosting small-scale manufacturing, brick kilns, and petroleum refineries, which emit particulate matter and gases. Additionally, Guwāhāti serves as a major transportation node, with National Highway 27 and 37 intersecting here, leading to significant vehicular emissions. The surrounding terrain, characterized by low-lying valleys and hills, can create microclimates that hinder pollutant dispersion, particularly during winter when temperature inversions are common. The urban–rural gradient sees a gradual transition from high-density built environments to agricultural lands, where seasonal crop residue burning occasionally worsens air quality. This unique geographic setting, combined with rapid urbanization, makes Guwāhāti's air quality a complex interplay of local emissions and regional atmospheric dynamics.

Guwāhāti's air quality follows a distinct seasonal pattern shaped by the monsoon climate and local meteorological conditions. In winter (December to February), pollution typically peaks due to a combination of factors: lower temperatures lead to increased use of biomass for heating, while calm winds and frequent temperature inversions trap pollutants near the ground, resulting in hazy conditions and reduced visibility. This period poses the highest risk for sensitive groups, such as children, the elderly, and those with respiratory issues, who should limit outdoor activities, especially during early mornings when pollution concentrations are highest. Spring (March to May) sees a gradual improvement as temperatures rise and winds pick up, aiding dispersion, though occasional dust storms from dry riverbeds can cause short-term spikes. The monsoon season (June to September) brings the cleanest air, as heavy rainfall washes pollutants from the atmosphere, and strong southwesterly winds disperse emissions effectively—this is the ideal time for outdoor pursuits. Post-monsoon (October to November) marks a transition, with decreasing rainfall and increasing agricultural residue burning in surrounding rural areas, leading to a gradual buildup of pollutants. Fog can also develop during cooler months, mixing with pollutants to form smog. To mitigate health impacts, residents are advised to monitor local air quality reports, use air purifiers indoors during peak pollution months, and plan outdoor exercises for late mornings or afternoons when dispersion is better. Avoiding heavily trafficked areas and wearing masks during high-pollution episodes can further reduce exposure risks.