Evening farm fires, missed by NASA satellite, drove Delhi's smog

An HT analysis of air-quality, weather and satellite data found that smoke from Punjab and Haryana farm fires caused Delhi's AQI to jump from 117 on Saturday to 324 on Monday. Most fires were lit in the evening, after the NASA satellite used to count stubble burning had passed. Night-time PM2.5 averaged 194, over three times India's daily limit.