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Sahtāh, nestled in the fertile plains of Bihar, India, occupies a geographically significant position within the Gangetic Basin. Located at approximately 25.8567° N, 85.2407° E, the city’s terrain is predominantly flat, characteristic of the Indo-Gangetic Plain, with an elevation of roughly 55 meters above sea level. This low-lying topography contributes to poor air circulation, particularly during periods of stagnant weather. The surrounding landscape is dominated by agricultural fields – primarily rice and maize cultivation – which, while vital to the regional economy, can contribute to seasonal particulate matter pollution through crop residue burning. Sahtāh’s proximity to the Ganges River, though providing a crucial water source, also influences local climate patterns and can exacerbate humidity, impacting pollutant dispersion. The urban–rural gradient around Sahtāh is relatively gradual, with small villages and agricultural hamlets blending seamlessly into the urban fabric. While Sahtāh itself is a small city with a population of 12,012, it sits within a broader region experiencing increasing industrial activity, particularly in nearby towns and cities along the Grand Trunk Road. This regional industrial belt introduces pollutants that can be transported to Sahtāh via prevailing winds. The flat, expansive terrain, combined with agricultural practices and regional industrial influence, creates a complex environment where air quality is particularly susceptible to external factors and local meteorological conditions.

Sahtāh’s air quality follows a distinct seasonal pattern dictated by the region’s monsoon climate. The pre-monsoon season (March-May) typically witnesses the worst air quality, characterized by high levels of particulate matter. This is largely due to agricultural burning of crop residue after the harvest, combined with rising temperatures and stagnant air masses. Temperature inversions, common during this period, trap pollutants close to the ground, intensifying their impact. The monsoon season (June-September) brings relief as strong winds and frequent rainfall effectively flush out pollutants, significantly improving air quality. However, heavy rainfall can also lead to increased humidity, which can exacerbate respiratory issues for some individuals. The post-monsoon season (October-November) sees a gradual return to poorer air quality as agricultural burning resumes, though generally less intense than in the pre-monsoon period. Winter months (December-February) are often characterized by fog, which further restricts air circulation and traps pollutants, creating conditions conducive to poor visibility and respiratory discomfort. Sensitive groups, including children, the elderly, and individuals with pre-existing respiratory conditions, should exercise caution during the pre-monsoon and winter months, limiting outdoor activity during peak pollution periods. Maintaining indoor air quality through ventilation and air purifiers is also advisable. The monsoon season offers the most favourable period for outdoor activities, though awareness of potential humidity-related issues remains important.