‘Air quality in Ghaziabad, Noida, Gurugram also better’

Air quality in the city immediately after Deepavali was the least bad since 2015, and in the satellite cities of Ghaziabad, Noida and Gurugram, it was the least toxic since 2017, according to data from the Central Pollution Control Board (CPCB).

“Overall, this year, Deepavali had seen less pollution in terms of both gaseous and particulate matter. This may be attributed to cumulative effects of ground level actions and introduction of green crackers in the market and favourable meteorological conditions,” the CPCB said in a statement on Monday.

The CPCB’s evening report, which records the average pollution over the previous 24 hours, said that the air quality index on Monday was 368. This is better than 390 a day after Deepavali in 2018, 403 in 2017 and 445 in 2016. The number not withstanding, the air quality was classified as ‘very poor’ like last year. When the index crosses 400, as it did in 2017 and 2016, it is recorded as ‘severe,’ or a State that warrants emergency action under the Graded Response Action Plan.

The average air quality reported by the CPCB hides the large variation in air quality during the day. For instance, at the air quality monitoring station in Rohini, the index had soared to 500 after 12.30 a.m. on Monday. According to the 2018 Supreme Court order, crackers were legally permitted only from 8 p.m. to 10 p.m. on Deepavali night.

More than the quantity of crackers burnt, it is the unfavourable meteorology that has a disproportionately higher influence on the air quality on the day following Deepavali. In 2017, for instance, the index classified Delhi’s air as “severe” at 403 even though the CPCB said that the concentration of pollutants was lower than in 2016, when too, after Deepavali the AQI was in the ‘severe’ category at 445. Both these years, early morning moisture and stalled winds retarded the flushing out of pollutants.

‘Stubble burning on rise’

CPCB officials said that the contribution of stubble burning in Punjab and Haryana in the pollutant mix in Delhi was increasing. Coupled with slowing down of wind speed, it would see the air quality gradually dip in the next few days.

“If 50% of the total load of firecrackers as compared to last year is added, the air quality index (AQI) may plunge to ‘severe’ category but for a shorter period of time unlike 2018, it persisted for several days and with relatively much less magnitude [half] than 2018 Deepavali period,” as per a forecast by meteorological agency SAFAR on October 26. The CPCB consults SAFAR forecasts.

On Monday, SAFAR said, while the air quality had dipped to ‘severe’, the concentrations were “much less than that of the last three years. The main factors contributing to this was high boundary layer wind speed. It helped to flush out and disperse high firecracker emissions.” In its post-Deepavali report, the CPCB said that the city’s average particulate matter (PM2.5) was 284 ug/m3. Anand Vihar station recorded highest 24 hourly average at 415 ug/m3. “The PM2.5 average of 37 stations on Deepavali day was found lower by 40 ug/m3 and PM10 was also found lower by 41 ug/m3 in 2019 as compared to 2018 Deepavali day,” the agency noted.