A Smokescape: AQI ‘Severe’ First Time This Year

Gurgaon: Dense smog enveloped the city on Friday morning as the air quality index (AQI) hit the ‘severe’ mark a day (472) for the first time this year. According to data from the Central Pollution Control Board (CPCB), Gurgaon’s pollution levels on Friday were the worst for the day after Diwali in the past six years.
The AQI of all five stations from which the CPCB collates its data in Gurgaon — Vikas Sadan, Gwal Pahari, Teri Gram, Sector 51 and Manesar — were all at ‘severe’ levels. The city’s AQI on Diwali (Thursday) was ‘very poor’ at 395. Even though there was a total ban on sale and use of firecrackers, that was hard to tell on Diwali evening with crackers continuously accompanying celebrations and frequently lighting up the skies.
According to data from CPCB, the AQI was at 298 a day after Diwali (October 31) in 2016, while it was at 397 on the corresponding day in 2017 (October 30). In 2018, the AQI was recorded at 389 on the day after Diwali (November 8), while it was 368 in 2019 (October 28). Last year, it was 460 on the corresponding day (November 15).
Apart from PM2.5 and PM10, other major pollutants such as nitrogen oxide, sulphur dioxide, nitrogen dioxide, nitrogen monoxide and ozone also showed a spike post Diwali compared to the last year’s levels, according to data from Haryana State Pollution Control Board (HSPCB).
Dispersion of pollutants is slow this year due to calm winds, an HSPCB official said. “This year, pollutant levels have remained high because of several reasons, such as a dip in temperature and wind speed. As a result, we have a higher AQI post Diwali. Moreover, incidents of cracker bursting were higher this time compared to the last year because there is no lockdown now. As Covid cases have also gone down significantly, movement of people has increased, which contributed to the rise in pollution too,” said HSPCB regional officer for Gurgaon (north) Kuldeep Singh told TOI.
Former CPCB head Dr Dipankar Saha said, “Crackers have very little to do with the increase of pollutants. Pre-Diwali AQI is always higher due to a rise in vehicular movement. Moreover, the average for the past 24 hours is reflected in the next day’s overall AQI. The deterioration of meteorological conditions compounds the problem.”
Saha, however, added, “It is urgent to have hourly AQI data on all critical days or when firecrackers are likely to be burst. Only ‘moderate’ AQI should be the criteria for permitting bursting of crackers. Regulators may need to revisit the criteria for bursting crackers. If green crackers make the AQI ‘severe’, their effectiveness needs re-evaluation.”
A day after Diwali, the PM10 level was recorded at 255.07 µg/m3 in 2019, which dipped to 233.48 µg/m3 on the corresponding day next year. This time, however, it surged to 670.6 µg/m3 on Friday. The PM2.5 level reflected a similar trend — while it was 933.3 µg/m3 on the day after Diwali in 2019, it declined to 633.1 µg/m3 in 2020 and spiked to 838 µg/m3 this year.
“We are expecting pollutants to start clearing up from November 7 onwards, as the wind speed will pick up,” HSPCB regional officer for Gurgaon (south) Sandeep Singh said.