Delhi's air pollution is once again "severe," with heavy smog making it harder to see. Will schools soon be closed?

Delhi air pollution: at 5 a.m. on Thursday, the AQI in Anand Vihar, Delhi, was 473 (or "severe plus").

Delhi air pollution: On Thursday morning, November 14, residents of Delhi awoke to "severe" air quality, one day after the nation's capital registered the worst AQI. The National Capital Region was covered in thick haze, which made it difficult to see. Despite the official pollution watchdog characterizing the decline as a "episodic event" and attributing it to a "unprecedentedly dense" fog, the Air Quality Index (AQI) went into "severe" status on Wednesday for the first time this season.

Anand Vihar in Delhi had an AQI of 466 ('severe plus') at 10 a.m. on Thursday, according to data from the Central Pollution Control Board (CPCB).

Among the places in Delhi with the poorest air quality were Aya Nagar, Ashok Vihar, and Wazirpur. When the air quality exceeds 400, it is classified as severe.

However, the Commission for Air Quality Management (CAQM) decided not to implement Stage 3 of the Graded Response Action Plan (GRAP), which calls for actions such as stopping elementary school lessons in person and outright prohibiting building.

The AQI, which averaged 418 at 4 p.m. on Wednesday, deteriorated to 436 by 6 p.m. (in the "severe" category) and reached 454 (in the "severe plus" category) by 9 p.m., according to data from the CPCB.

Notably, according to the CPCB's 4 pm daily bulletin, Stage 4 of Grap is initiated when the 24-hour average AQI exceeds the "severe plus" threshold. As of right now, Grap Stage 2, which went into force on October 22, is still in place.

Usually implemented on "severe" days for air quality, Stage 3 of Grap prohibits construction and demolition, permits states to postpone in-person instruction for kids up to Class 5, and emphasizes the need for improved public transit.

The 24-hour AQI in Delhi
Every day at 4 p.m., Delhi's 24-hour AQI was recorded at 418, up from 334 the day before.

However, the CAQM stated that because of the increased winds, the AQI is anticipated to return to the "very poor" category and the pollutant concentration is projected to begin displaying a falling trend on Thursday and beyond.

"After a comprehensive review, the sub-committee decided to closely monitor the situation before implementing Stage-3 of GRAP and will reassess the status on Thursday," the CAQM stated in a post on X.

The CAQM stated in a different tweet on the microblogging site that its subcommittee had seen the sharp increase in Delhi's AQI since the morning due to this "episodic event."

Pollutants were trapped as the national capital saw its first heavy fog and the season's lowest midday temperature on Wednesday.

On Tuesday, the highest temperature in Delhi (Safdarjung) was 32.8 degrees Celsius; on Wednesday, it was 27.8 degrees Celsius.

According to data from the Central Pollution Control Board (CPCB), Hajipur, Bihar, recorded the second-worst AQI measurement in the nation on Wednesday, with a score of 417.

According to the CPCB, 30 of Delhi's 36 monitoring sites reported "severe" air quality.

A score of zero to fifty is regarded as "good," 51 to 100 as "satisfactory," 101 to 200 as "moderate," 201 to 300 as "poor," 301 to 400 as "very poor," 401 to 450 as "severe," and over 450 as "severe plus."

The CPCB reports that on three days in January, Delhi's AQI was in the severe category. The AQI was recorded at 447 on January 14 and 409 on January 24 and 26.

Authorities may enforce limitations under the third stage of the GRAP, such as prohibiting construction and demolition operations and the use of BS-lll gasoline and BS-IV diesel light motor vehicles, if the city's air quality is still classified as severe on Thursday.