Sonāimukh, nestled in the Nagaon district of Assam, India, occupies a geographically significant position within the Brahmaputra River valley. Located at approximately 24.73°N, 92.89°E, the town’s terrain is predominantly alluvial, a direct consequence of the region’s history of riverine deposition. The elevation is relatively low, averaging around 30 meters above sea level, contributing to a generally flat landscape. The Brahmaputra River flows nearby, influencing local climate and potentially impacting air quality through humidity and occasional flooding events. Sonāimukh’s urban character is that of a developing town, transitioning from a primarily agricultural setting to a more mixed economy with some light industries and trading activities. The surrounding landscape is dominated by fertile agricultural land, primarily rice paddies and tea plantations, which are characteristic of Assam’s rural economy. This proximity to agricultural zones introduces potential sources of air pollution, including biomass burning during harvest seasons and fertilizer application. The urban–rural gradient is gradual, with smaller villages and agricultural fields seamlessly blending into the town’s periphery. Further afield, the landscape gradually rises towards the foothills of the Mikir Hills, influencing regional wind patterns. The valley’s topography, combined with the river’s presence, can lead to stagnant air conditions, particularly during periods of low wind speed, exacerbating the impact of local pollution sources. The town’s location within a densely populated and agriculturally intensive region means that regional air pollution events can significantly impact Sonāimukh’s air quality.

Sonāimukh’s air quality experiences a distinct seasonal cycle dictated by the region’s monsoonal climate. The monsoon season, typically spanning June to September, brings heavy rainfall and generally improved air quality due to frequent precipitation washing away particulate matter and strong winds dispersing pollutants. However, the preceding pre-monsoon months (March-May) often witness a concerning rise in air pollution, primarily due to agricultural burning – farmers clearing crop residue after the harvest. This practice releases significant quantities of smoke, particulate matter, and other harmful gases. The dry season (November-February) presents a mixed picture. While temperatures are cooler, the lack of rainfall and frequent fog, especially in December and January, can trap pollutants near the ground, leading to periods of reduced visibility and potentially elevated air quality concerns. Temperature inversions, common during these colder months, further exacerbate this issue by preventing vertical mixing of the air. During the monsoon, humidity is high, which can irritate respiratory systems, particularly for those with pre-existing conditions. The pre-monsoon period demands heightened caution for vulnerable groups like children, the elderly, and individuals with respiratory illnesses; limiting outdoor exertion during peak burning times is advisable. The dry season’s fog necessitates careful monitoring and awareness of potential air quality impacts. Throughout the year, maintaining good ventilation indoors and avoiding exposure to smoke from cooking fires are crucial preventative measures.