A thick shroud of menacing grey haze blanketed the national capital on 5 November as pollution level breached the safe limit by over 17 times at places, prompting Chief Minister Arvind Kerjriwal to describe Delhi as a "gas chamber" and seek the Centre's intervention.
Kejriwal appealed to people to minimise the use of private vehicles in view of the situation and switch to public transportation facilities.
The extent of pollution surpassed even the post-Diwali levels, while smog brought down visibility to around 200 metres across the city. Monitoring agencies recorded 'severe' quality air and advised people to avoid going outdoors.
Kejriwal told a press conference that the smog was mainly a product of raging farm fires in neighbouring Punjab and Haryana. Later, he raised the issue with Union Environment Minister Anil Dave in a meeting at the latter's residence.
While the 24-hour average of respirable pollutants PM 2.5 and PM 10 was 355 and 482 micrograms per cubic metre respectively, real-time figures were alarmingly high.
Anand Vihar, for instance, recorded PM 10 level at 1,711 micrograms per cubic metre at 2 PM -- around 17 times above the safe limit.
The safe limits of these ultrafine particles are 60 and 100 respectively. Even the level of gaseous pollutants like NO2 violated the prescribed standards for human inhalation as per real-time readings.