New Delhi, Nov. 12 -- Delhi's air quality plunged into the 'severe' category for the first time this year on Tuesday, prompting the Commission for Air Quality Management (CAQM) to enforce emergency measures under Stage 3 of the Graded Response Action Plan (Grap) across the National Capital Region (NCR). The restrictions, which took immediate effect, include a ban on private construction and demolition work and curbs on BS-3 petrol and BS-4 diesel four-wheelers in Delhi, Gurugram, Faridabad, Ghaziabad and Gautam Budh Nagar.

The decision followed a sharp overnight spike in the city's air quality index (AQI) - from 362 ('very poor') at 4pm on Monday to over 400 ('severe') by 1am Tuesday, and further touching 425 at 9am, according to the Cen...