Parsāgarhi, a small city nestled within the plains of Bihar, India, occupies a geographically significant position at coordinates 26.0935°N, 87.0672°E. The terrain is characteristically flat, typical of the Indo-Gangetic Plain, with a low elevation contributing to limited natural air dispersion. The city’s location is deeply interwoven with the agricultural landscape of Bihar, surrounded by extensive rice paddies and wheat fields, common features of the region’s agrarian economy. While not directly adjacent to a major river, Parsāgarhi benefits from the regional hydrological network fed by the Ganges and its tributaries, influencing local humidity and potentially trapping pollutants during stable atmospheric conditions. The urban-rural gradient is relatively sharp; the city itself is compact, with a population of approximately 22,057, quickly transitioning to rural farmland. This proximity to agricultural practices introduces seasonal biomass burning – post-harvest crop residue burning – as a significant localised pollution source. The lack of substantial industrial belts *within* Parsāgarhi itself doesn’t preclude the influence of regional industrial activity further afield, transported by prevailing winds. The flat topography and limited wind corridors exacerbate the concentration of pollutants, making Parsāgarhi particularly vulnerable to air quality issues. Understanding this interplay of geography and land use is crucial for effective mitigation strategies.

Parsāgarhi experiences a distinct seasonal air quality pattern dictated by the monsoon and post-monsoon periods. The summer months (April-June) bring high temperatures and stagnant air, leading to a build-up of dust and local emissions. While rainfall is minimal, the heat exacerbates ground-level ozone formation. The arrival of the monsoon (July-September) offers temporary relief, with rainfall scavenging pollutants from the atmosphere. However, increased humidity can also promote secondary pollutant formation. The post-monsoon season (October-November) is arguably the most challenging. Cooler temperatures create temperature inversions, trapping pollutants near the ground, coinciding with the peak of post-harvest crop residue burning. This period sees a significant deterioration in air quality. Winter (December-February) brings cool, dry conditions and often fog, further reducing visibility and trapping pollutants. Sensitive groups – children, the elderly, and those with respiratory conditions – should limit outdoor activity during October-November and December-February. Avoiding peak hours (early morning and evening) is advisable. During the monsoon, while air quality improves, mould growth indoors can pose respiratory risks. Maintaining good ventilation and avoiding damp areas is recommended.