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AQI turns ‘very poor’ a day after Diwali, experts and officials say city air cleaner than previous years
Gurugram: A day after Diwali, the city’s air quality veered into the “very poor” category for the first time this season, with 372 on the Central Pollution Control
Gurugram: A day after Diwali, the city’s air quality veered into the “very poor” category for the first time this season, with 372 on the Central Pollution Control Board’s air quality index (AQI) bulletin. At 4pm on Monday, the average 24-hourly concentration of PM2.5 stood at 370ug/m3, more than six times the safe limit of 60ug/m3 (as per the National Ambient Air Quality Standards), and 37 times the World Health Organisation’s safe limit of 10ug/m3. By 8pm, the AQI had risen to 384.
This is up from 299 (poor) the previous day, according to data from the Haryana State Pollution Control Board’s only air monitor in the city at Vikas Sadan. However, experts and officials both said that the AQI of 372 was erroneous, and that Gurugram has seen its “cleanest” Diwali in at least four years despite residents burning crackers deep into the night. “The data from the air quality monitor must be wrong, or the way the AQI is being calculated is wrong. It is done automatically and might need some correction,” said Rajesh Garhia, senior scientist, HSPCB.
Experts also concurred with Garhia’s claim that the data was either incorrect or mistakenly represented. Sachin Panwar, a city-based air quality scientist, said, “This time, we have recorded an average concentration of PM2.5, which is the most prominent pollutant in the city, lesser than last Diwali. Last year, we saw PM2.5 matter concentration touching as much as 4,079ug/m3 in certain areas where firecrackers were being used widely. This year, based on data from the same hotspots in Manesar, Udyog Vihar and Sector 81, we have seen averages between 2,800ug/m3 to 3,000ug/m3.”
Panwar added that favourable meteorology was the underlying reason for this year’s dip in post-Diwali pollution. “We had strong winds blowing on Sunday night, as well as on Monday morning that helped to disperse some pollutants,” said Panwar. He added that the wind direction, blowing from the south-west, would have carried some of airborne pollutants toward Delhi, adversely affecting air quality in the Capital.
According to a district-wise list of air pollution monitoring data that Garhia shared with Hindustan Times on Monday, Gurugram had a daily average AQI of 299 the morning after Diwali (at 6am), up from 239 the previous day. This indicates an improvement from last year, when Gurugram recorded 389 on the CPCB’s daily AQI bulletin on November 8, 2018 (a day after Diwali), up from 212 (poor) on November 7.
Nevertheless, bursting of fireworks sent particulate matter concentrations soaring on Diwali night. Between 9pm on Sunday night and 1am on Monday, the HSPCB’s air quality monitor showed that the PM2.5 levels had surpassed the 500ug/m3 mark, which is the maximum value which can be displayed by the monitor.
In other parts of the city, private data showed that PM2.5 levels touched as much as 592ug/m3 late last night, while PM10 levels touched as much as 528ug/m3. Between 7pm and 4am, the city’s AQI rose from 292 (poor) to 344 (very poor), according to Vikas Sadan data.
The average PM2.5 level, according to HSPCB ratified data, jumped from 116.98ug/m3 on Sunday to 252.12ug/m3 on Monday. The concentration of SO2 jumped from 8.59ug/m3 on Sunday to 84.51ug/m3 on Monday, which Garhia identified as “a clear indicator of firecracker use.”
According to a CPCB forecast, air quality is expected to touch emergency levels tomorrow, with a predicted AQI of 586 (which surpasses even the ‘severe’ category), before dropping back into the ‘poor’ category on Wednesday, with 290 on the AQI. “This is because of weather conditions. It was very cloudy in Gurugram on Monday, so sunlight has been sparse and this will keep pollutants extremely close to the ground, and the average AQI of the city over the next 24 hours could go up,” said Panwar.
However, a senior scientist with the CPCB clarified that emergency conditions would not last long. “We are expecting some precipitation and stronger winds over the next couple days, as a result of cyclone Kyarr in the Arabian Sea. It should make a difference and mitigate the impact of firecrackers by Wednesday or Thursday.”
