Delhi, India

Delhi, India, faces an annual air quality crisis, particularly in November, when its AQI frequently surpasses 500, officially categorized as 'hazardous.' The average winter PM2.5 concentration has been recorded at 250 µg/m³, which is 10 times higher than the WHO guideline. This severe pollution is primarily a result of agricultural stubble burning in surrounding regions, vehicle exhaust, and construction dust, all of which combine to envelop the capital in a thick blanket of smog for weeks. The persistently poor air quality in Delhi contributes to a significant number of excess respiratory deaths each year.