Delhi’s Post-Diwali Air Quality ‘Very Poor’, But Best In 7 Years

After residents disobeyed the ban on firecrackers in many areas of the capital on Diwali night, Delhi recorded “very poor” air quality on Tuesday. However, the pollution levels for the following day were the lowest since 2015 thanks to favourable meteorological conditions that reduced the impact of the fireworks and stubble burning.

However, “poor” air quality was noted in the nearby cities of Ghaziabad (266), Noida (299), Greater Noida (272), Gurugram (292) and Faridabad (289). A score of 0 to 50 on the air quality index (AQI) is regarded as “excellent,” 51 to 100 as “acceptable,” 101 to 200 as “moderate,” 201 to 300 as “poor,” 301 to 400 as “extremely poor,” and 401 to 500 as “severe.”

By 1 am, the PM2.5 concentration in the capital had increased to about 550 micrograms per cubic metre in most locations due to the firework emissions. By 4 pm, however, the PM2.5 concentrations had fallen below 150 micrograms per cubic metre as a result of warmer and windier weather, which is better for the dispersion of pollutants.

PM2.5 are tiny particles with a diameter of 2.5 microns or less that can penetrate the respiratory system deeply, make it to the lungs, and then enter the bloodstream.

In Delhi, the AQI was 310 around 11 p.m. on Monday. It rose to 326 at 6 am on Tuesday, remained steady until 9 am, and then started to fall.

The Central Pollution Control Board (CPCB) began keeping track of air quality statistics in 2015, when the 24-hour average AQI reached 303 at 4 p.m. It was the lowest for the day after Diwali since that time.

The Delhi AQI was 360 in 2015, 445 in 2016, 403 in 2017, 390 in 2018, 368 in 2019, 435 in 2020, and 462 in 2021 on the day following Diwali.

This year, Diwali was celebrated early in the season, so the weather was reasonably warm and windy, which prevented firecrackers from bursting quickly and lessened the impact of stubble burning.

In 2021 and 2020, Diwali was observed on November 4 and November 14, respectively, when the weather conditions were favourable and the winds were quiet.

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