Unfavourable weather conditions coupled with extra pollutants from firecrackers in Delhi-NCR led to "severe-plus" or "emergency" air quality in the national capital with toxicity not likely to improve for at least 2 more days.
With maximum fire counts from stubble burning in neighbouring states — 2,100, which is four times higher than last year, on Thursday, Delhi and areas around it on Friday were found more polluted than Thursday, a day after Diwali.
The Air Quality Index (AQI) of Delhi was 423 (Severe) on Friday, against 390 (Very poor). The AQI deteriorated on Friday across the region with an AQI of 460 in Faridabad, 441 in Ghaziabad, 447 in Greater Noida, 453 in Bhiwadi, 442 in Noida and 400 in Gurugram.
In 2017, the AQI of Delhi two days after Diwali was 389 or ‘very poor’.
“Currently, Delhi has calm wind with indefinite direction. A western disturbance has entered Jammu and Kashmir, which has cut off the winds. This will persist for November 10 and 11, so conditions will remain around severe for the next two days,” said Mahesh Palawt, Director of Skymet.
According to the System of Air Quality and Weather Forecasting And Research (SAFAR), Delhi’s air quality is showing improvement but at a very slow pace due to weather conditions.
“There is a possibility that wind may pick up at upper level, late in the night and push the level of pollution and keep it in SEVERE zone tomorrow (Saturday) with intensified Fog which will further help in trapping the pollutants,” said a forecast from SAFAR.
It, however, adds that the contribution of stubble fire emissions is marginal as upper winds are northerly.
The concentration of PM2.5 and PM10, or particles with diameter less than 2.5 mm and 10mm, remained in ‘severe-plus’ or ‘severe’ levels.
The average concentration of PM2.5 and PM10 in Delhi was 327 and 482 microgrammes per cubic meters on Friday. Across NCR, it was 320 and 477 units, respectively.
“Delhi may see some improvement after Saturday, if the winds catch up,” said Shambhavi Shukla, research analyst from the Centre for Science and Environment (CSE).
This year’s Diwali was more polluted than last year’s due to heavy fireworks and unfavourable weather conditions like low temperature and wind speed, triggering a spike in particle pollutants, a report said on Friday.
The report said that this year’s Diwali, which was on November 7, was as polluted as Diwali in 2016. The Central Pollution Control Board (CPCB) report also shows a rise in harmful gases such as Carbon Monoxide (CO), Nitrogen dioxide (NO2) and Sulphur dioxide (SO2).
“Particulate concentrations were slightly higher this Diwali as compared to last Diwali (2017),” said the CPCB report. It, however, adds that since in 2017 Diwali was observed on October 19 as against November 7 this year, the meteorological conditions, which govern the dispersion of pollutants, were different.
“Compared with the average Particulate Matter during November 1 to 7 in 2017 with the same period this year, the city average particulate concentration for Delhi is lower in 2018,” the report pointed out.
Apart from fireworks and unfavourable wind speed, stubble burning this year had more effect on Delhi’s air quality around Diwali, against last year’s celebrations (October 19).
On Diwali, there were a total 4,204 fire incidents compared to 1,702 in 2017.
“Diwali-day data shows that the PM10 and PM2.5 values have increased this year compared to 2017. However, the data are similar to Diwali day of 2016 which was observed on 30th October,” said the report.
It added that in 2017, the wind directions on Diwali day were east and southeast while in 2018 it was north-west, which might have added pollutant load from stubble burning.
“Contribution of stubble burning in overall PM2.5 concentration during Diwali this year has been estimated at 10 per cent.” said the report.
The report found that apart from the Dwarka subcity, the pollutants — PM2.5 and PM10 — were high almost everywhere else when compared to 2017. Other pollutants — CO, NO2, SO2 — varied at different places compared to 2017.
The PM2.5 on Diwali 2017 was 638 and 496 units at Janakpuri and Parivesh Bhawan, while this year, these values were 988 and 900 units respectively.
The CO levels at Dilshad Garden were 983 units in 2016, 1,423 in 2017 and 1,441 in 2018. At Shadipur, the NO2 levels were 58 units in 2017 against 94 in 2018. (IANS)