India, Jan. 30 -- New Delhi

Curbs under Stage 3 of the Graded Response Action Plan (Grap) were imposed in Delhi-NCR on Wednesday due to a deterioration in the air quality index (AQI) to the "very poor" category, the Commission for Air Quality Management (CAQM) said, bringing in bans on private construction and demolition activities, hybrid sessions for students up to Class 5, and restrictions on BS-3 petrol and BS-4 diesel four-wheelers, among others.

Delhi's 24-hour average AQI on Wednesday was 365 ("very poor"), worse off by nearly 100 points from a reading of 276 ("very poor") recorded a day before, according to the Central Pollution Control Board's (CPCB) daily bulletin.

"The AQI of Delhi which was recorded as 276 on January 28, ex...