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Khera Kalān, a small village nestled within the sprawling urban landscape of Delhi, India, occupies a geographically complex position. Located at approximately 28.7781° N, 77.0988° E, it sits on relatively flat terrain, characteristic of the Indo-Gangetic Plain. Its proximity to Delhi, a megacity of over 30 million people, fundamentally shapes its environmental conditions. The surrounding landscape is a mosaic of agricultural fields, gradually transitioning into the dense urban fabric of Delhi. This urban–rural gradient means Khera Kalān experiences a constant influx of pollutants originating from the city, alongside agricultural emissions from nearby farming practices, particularly during harvest seasons. The elevation is low, around 219 meters (719 feet) above sea level, contributing to temperature inversions, a key factor in trapping pollutants. While not directly adjacent to a major river, the Yamuna River flows relatively close, influencing local humidity and potentially impacting the dispersion of airborne particles. The village’s location within the National Capital Region (NCR) exposes it to the cumulative impact of industrial activity concentrated in areas like Ghaziabad and Faridabad, further exacerbating air quality challenges. The prevailing winds, often originating from the west, carry pollutants from these industrial belts towards Khera Kalān and other parts of Delhi, creating a regional pollution network. The soil composition, largely alluvial, also influences dust generation, particularly during dry periods, adding to the particulate matter burden.

Khera Kalān’s air quality follows a distinct seasonal pattern dictated by meteorological conditions and regional pollution sources. The winter months (November to February) are typically the most challenging. Cold temperatures frequently lead to temperature inversions, where a layer of warm air traps cooler air and pollutants near the ground, resulting in stagnant air and elevated concentrations of particulate matter. Dense fog, common during this period, further restricts dispersion. Agricultural burning in surrounding regions, a practice to clear crop residue, significantly contributes to the pollution load. Spring (March-April) brings a slight improvement as temperatures rise and winds increase, aiding in pollutant dispersal, though dust storms originating from the Thar Desert can occasionally degrade air quality. The monsoon season (June to September) offers a period of relative respite. Rainfall effectively washes pollutants from the atmosphere, and increased wind speeds enhance ventilation. However, heavy rainfall can also lead to waterlogging and the release of pollutants from stagnant water sources. The post-monsoon period (October) sees a gradual deterioration as winds weaken and temperatures begin to drop, setting the stage for the winter pollution peak. Sensitive groups, including children, the elderly, and individuals with respiratory conditions, should exercise caution during the winter months, limiting outdoor exposure and using air purifiers when possible. During periods of high dust, wearing masks is advisable for everyone. During the monsoon, while generally cleaner, vigilance regarding waterborne diseases is important.