Intrusion of dust from countries northwest of India and particulate matter from farm fires in stubble burning states are being noted in Delhi’s air, but high wind speed is helping in their dispersion. This could change by next week due to an “immediate stagnation” of winds brought on after the withdrawal of monsoon over Delhi-NCR, which is expected around October 1, air pollution and weather experts said on Sunday.
An official from the Ministry of Earth Sciences said, “Dust lifting process is happening from areas around Afghanistan and Rajasthan, because there is suspension of dust as temperature rises in those regions. Since wind speed over Delhi is very high, it is unlikely to affect air quality for now.”
The official added, “The immediate stagnant wind conditions brought on after the withdrawal of monsoon and the dust lifting… these two combined conditions could affect air quality.”
As temperatures dip, the ability of pollutants to accumulate also rises. September this year has been warmest in five years. Because of the lockdown, the city has seen good quality air, the cleanest in several years but the combined effect of change in wind direction, dipping temperatures and stubble burning means Delhi’s air is going to turn foul again soon.
Kuldeep Srivastava, head of the India Meteorological Department’s (IMD) regional weather forecasting centre in Delhi, said the withdrawal of monsoon would begin on Monday from west Rajasthan. “Conditions are favourable for withdrawal from most parts of northwest India in subsequent two-three days, including Delhi-NCR,” he added.
Pawan Gupta, senior scientist at Universities Space Research Association, NASA, also posted on Twitter Saturday: “Dust transport from the west is expected to affect air quality in northern-central India over the next two-three days.” Gupta also posted data from a NASA satellite that showed close to 290 fires in Punjab on Saturday and over 20 in Haryana on Sunday.
IMD officials also said smoke from farm fires in Punjab and Haryana in the form of particulate matter of 2.5 micrometres (PM2.5) is being noticed in Delhi’s air.
They said northwesterly winds were blowing over the city, which facilitate the transport of pollutants from stubble burning states.
Punjab Pollution Control Board member secretary Karunesh Garg said nearly 60 farm fires have been confirmed in Amritsar and Tarn Taran districts between September 22 and 26. “We visited 129 sites, of which 72 were reported to not have any fires — meaning there could be some other fire, such as a fire in the city area or a cremation ground in an open village, that the satellite may have captured,” Garg said.
He added that fines totalling Rs 55,000 have been imposed on farmers for 15 fire incidents so far and proceedings for others are underway.
Haryana State Pollution Control Board member secretary S Narayanan said 55 farm fires have been reported in the state between September 25 and 27, mostly in Karnal district. He said 34 incidents were reported on Sunday.
“We have shared a list of 30 top stubble burning villages — based on our experience of previous years — to all DCs for effective monitoring and enforcement. Hopeful of a sharp reduction in the coming season compared to previous years,” he said.
A forecast from the Centre-run air quality and weather forecasting agency SAFAR on Sunday said, “Late withdrawal of monsoon and the associated high-pressure system and stagnant wind conditions are likely to influence Delhi’s air quality negatively by the end of next week.”
Delhi’s air quality index on Sunday was 117 in the ‘moderate’ range, as per data from the Central Pollution Control Board.