New Delhi: What can be termed as a piece of good news for all Delhiites and people living around the city, the National Capital on Sunday recorded an air quality index (AQI) of 259, which was the lowest for the day before Diwali in seven years, the Central Pollution Control Board (CPCB) data showed.
However, it is important to note that the air quality in the capital is predicted to turn “very poor” on Monday morning while it could worsen to the “severe” category on Tuesday due to emissions from firecrackers and an increase in the share of smoke from stubble burning because of a favourable wind speed and direction.
An AQI between zero and 50 is considered “good”, 51 and 100 “satisfactory”, 101 and 200 “moderate”, 201 and 300 “poor”, 301 and 400 “very poor”, and 401 and 500 “severe”.
Delhi Pollution:  PAST YEARS’ DATA

In 2021, the AQI on November 3 (a day before Diwali) was 314.
It had shot up to 382 on the Diwali day and 462 the next day.
In 2020, Delhi recorded an AQI of 296 a day before Diwali (November 13)
The quality worsened to 414 on Diwali and 435 the day after.
The capital logged an AQI of 287 on the day before the festival in 2019.
It worsened to 337 on Diwali (October 27) and further to 368 the next day.
The AQI was 338 on the day before Diwali in 2018.
Interestingly, it improved to 281 on the Diwali day before aggravating to 390 the next day.
According to the data shared by CPCB, the AQI was 302 and 404 on the day before Diwali in 2017 and 2016

In case firecrackers are burst like last year, the air quality may plunge to “severe” levels on the night of Diwali itself and continue to remain in the “red” zone for another day. The contribution of stubble burning to Delhi’s PM2.5 pollution has so far remained low (up to 5 per cent) due to a slow transport-level wind speed.
“However, the transport-level wind direction and speed is likely to become very favourable from Monday afternoon. It will increase the share of stubble burning in Delhi’s PM2.5 pollution to 15-18 per cent on October 25 and push the air quality into the ‘severe’ category,” said Gufran Beig, founder project director, SAFAR.
(With PTI Inputs)