Barauli, a small city nestled within the plains of Bihar, India, occupies a geographically significant position at coordinates 26.3815°N, 84.5872°E. The terrain is predominantly flat alluvial land, characteristic of the Gangetic Plain, with an elevation hovering around 75 meters above sea level. This low-lying landscape contributes to limited natural dispersion of pollutants. The city is situated within a largely agricultural zone, dominated by rice and wheat cultivation, with smaller pockets of vegetable farming. The Gandak River flows relatively close, influencing local humidity and occasionally contributing to stagnant air conditions during periods of low flow. While not directly within a major industrial belt, Barauli serves as a regional market town, attracting vehicular traffic and small-scale industrial activity like brick kilns and rice mills. The urban-rural gradient is pronounced; the city core is densely populated, transitioning rapidly to agricultural fields. This proximity to agricultural practices introduces seasonal biomass burning, a significant source of particulate matter. The surrounding landscape offers minimal topographical features to break up wind patterns, leading to pollutant accumulation, particularly during winter months when temperature inversions are common. The city’s location within the Indo-Gangetic Plain, known for its poor air quality, exacerbates these challenges.

Barauli experiences a distinct seasonal air quality pattern. The post-monsoon season (October-November) consistently presents the poorest air quality. Reduced wind speeds following the monsoon, coupled with temperature inversions trapping pollutants near the ground, lead to significant particulate matter build-up. Biomass burning from agricultural residue disposal further worsens conditions. December and January continue this trend, with cold air and stagnant conditions exacerbating pollution. The winter months are particularly hazardous for individuals with respiratory conditions. February and March see a gradual improvement as temperatures rise and wind speeds increase, though dust from agricultural activities remains a concern. The pre-monsoon season (April-May) brings hot, dry winds that can transport dust and pollutants from surrounding areas, creating localised hotspots. The monsoon season (June-September) generally offers the cleanest air, as rainfall effectively washes away pollutants and increased humidity suppresses dust. However, increased traffic congestion due to waterlogged roads can offset some of these benefits. Sensitive groups – children, the elderly, and those with pre-existing respiratory or cardiovascular illnesses – should limit outdoor exposure during October-February and take precautions during peak hours in April-May.