Sarmastpur, Bihar, situated at approximately 25.9490° N, 85.5751° E, occupies a geographically significant position within the fertile Gangetic plains of eastern India. The city’s terrain is predominantly flat, characteristic of the Indo-Gangetic Plain, with an average elevation of around 35 meters above sea level. This low elevation contributes to a tendency for pollutants to accumulate, particularly during periods of stagnant air. Sarmastpur lies within a region heavily influenced by the monsoon climate, and is bordered by agricultural lands, a crucial factor impacting air quality. The surrounding landscape is dominated by expansive fields of rice and wheat, leading to seasonal agricultural burning which significantly contributes to particulate matter pollution. While not directly adjacent to a major river, the proximity to the Ganges River basin influences regional weather patterns and humidity levels, which can affect pollutant dispersion. The urban–rural gradient around Sarmastpur is gradual, with smaller villages and agricultural settlements blending into the city’s periphery. The lack of significant topographical features—hills or valleys—limits natural ventilation and exacerbates the trapping of pollutants. Industrial activity in the broader Bihar region, though not immediately adjacent to Sarmastpur, can still contribute to regional air pollution transported by prevailing winds. The flat, expansive nature of the landscape, combined with agricultural practices and regional industrial emissions, creates a complex interplay of factors influencing Sarmastpur’s air quality.

Sarmastpur’s air quality follows a distinct seasonal pattern dictated by the monsoon climate and agricultural practices. The pre-monsoon season (March-May) typically witnesses the worst air quality, characterized by elevated levels of particulate matter. This is largely due to agricultural residue burning – farmers clearing fields after the harvest – releasing vast quantities of smoke and pollutants. Hot, dry winds exacerbate the situation, preventing effective dispersion. The monsoon season (June-September) brings relief, with increased rainfall and wind speeds naturally cleansing the atmosphere. However, humidity levels rise significantly, which can still impact respiratory health for some. Post-monsoon (October-November) sees a resurgence of agricultural burning, though often less intense than in the pre-monsoon period. Winter months (December-February) are often marked by fog, particularly in the mornings. This fog traps pollutants near the ground, creating localized pockets of poor air quality. Temperature inversions, common during winter nights, further contribute to this phenomenon, preventing vertical mixing of the air. Sensitive groups, including children, the elderly, and individuals with respiratory conditions, should exercise caution during these periods, limiting outdoor activity and wearing appropriate masks. The agricultural cycle is the dominant driver of seasonal air quality fluctuations, making sustainable agricultural practices crucial for long-term improvement. While the monsoon offers temporary respite, consistent air quality management strategies are needed to mitigate the impacts of agricultural burning and other pollution sources.