An air emergency was declared in the National Capital on Thursday with its air quality index nosediving into ‘severe’ days ahead of Diwali. Delhi chief minister Arvind Kejriwal announced that in light of the rising pollution levels, all government and primary closed on Friday and Saturday. The Delhi government imposed a ban on non-essential construction activities and on the plying of BS-3 petrol and BS-4 diesel cars in Delhi Gurugram, Faridabad, Ghaziabad and Gautam Budh Nagar. On Friday morning, the overall AQI in Delhi was in ‘severe’ category with Lodhi Road area at 438, Jahangirpuri at 491, RK Puram area at 486 and around IGI Airport (T3) 473.

An AQI between zero and 50 is considered good, 51 and 100 satisfactory, 101 and 200 moderate, 201 and 300 poor, 301 and 400 very poor, and 401 and 500 severe and above 500, it is hazardous.

While Delhi’s AQI has turned severe so far, scientists have warned of further deterioration in the air quality. On Thursday 10pm, the AQI dipped to 422, the worst of this season.