India, Dec. 14 -- Air quality in the National Capital Region plummeted sharply on Saturday, with at least four cities recording a "severe" air quality index (AQI) and accounting for four of the five cities across the country that recorded AQI readings above 400. Among these, Noida fared the worst, recording an AQI of 455, and was the only city to breach the 450 mark.

Gurugram, on the other hand, fared relatively better, clocking an AQI of 322 ("very poor") on the day. According to the Central Pollution Control Board's (CPCB's) daily AQI bulletin, Delhi recorded an AQI of 431, Greater Noida recorded an AQI of 442, and Ghaziabad recorded an AQI of 430, all of which are categorised as "severe".

On Friday, Ghaziabad recorded an AQI of 363, ...