The share of stubble burning in Delhi's PM2.5 pollution jumped to 38 per cent on Thursday, which, experts said was the reason behind the thick layer of pungent smog over the national Capital.
The satellites detected 3,212 residue burning events in the six States on Thursday. The Ministry of Agriculture data showed that 2,666 cases detected in Punjab, 128 in Haryana, 40 in UP, one in Delhi, 54 in Rajasthan and 323 in MP.
Gufran Beig, founder project director, National Capital Region, System of Air Quality and Weather Forecasting And Research (SAFAR), a forecasting agency under the Ministry of Earth Sciences, said, "The share of stubble burning in Delhi's pollution has increased to around 38 per cent which is quite significant."
The air pollution situation is the worst in Noida, Uttar Pradesh which falls into the path of emissions being transported from stubble burning, he said.
"Gurugram and Lodhi Road areas which do not fall into this path are the least affected," Beig said.
Delhi-NCR’s air quality slipped back into the "severe" zone Thursday morning amid raging farm fires and stagnant conditions at night. The overall Air Quality Index stood at 419 at 9 AM in Delhi, Noida and Greater Noida .
"The overall air quality in Delhi will continue to remain in the severe category till Friday morning. There will be slight improvement afterwards.
A major relief is likely on Saturday due to predicted improvement in meteorological conditions — wind speed and direction," Beig said.
An AQI (air quality index) of above 400 is considered "severe" and can affect healthy people and seriously impact those with existing illnesses.
According to the Energy Policy Institute at the University of Chicago's (EPIC) Air Quality Life Index (AQLI) released in June, the residents of Delhi stand to lose 10 years of life expectancy due to poor air quality.
Punjab had on Wednesday reported 3,634 farm fires, the highest this season so far, though their share in Delhi PM2.5 pollution stood at just 12 per cent due to unfavourable transport-level wind speed.
The number of farm fires stood at 1,842 on Tuesday, 2,131 on Monday, 1,761 on Sunday, 1,898 on Saturday and 2,067 on Friday.
SAFAR said the share of stubble burning in Delhi's PM2.5 pollution was "moderate" at 12 per cent due to unfavourable transport-level wind speed.
Transport-level winds blow in the lowest two layers of the atmosphere — the troposphere and stratosphere— and carry smoke from farm fires to the national capital region.
Farm fires accounted for 14 per cent of the PM2.5 pollution in the national capital on Tuesday, 22 per cent on Monday, 26 per cent on Sunday and 21 per cent on Saturday, according to the System of Air Quality and Weather Forecasting and Research (SAFAR).
PM2.5 are fine particles that are 2.5 microns or less in diameter and can travel deep into the respiratory tract, reaching the lungs and entering the bloodstream.
The Commission for Air Quality Management had last week said the increased incidents of stubble burning in Punjab this year "is a matter of serious concern".
According to the Indian Agricultural Research Institute (IARI), Punjab reported 71,304 farm fires between September 15 and November 30 last year and 83,002 farm fires in the corresponding period in 2020.
Last year, the share of farm fires in Delhi's PM 2.5 pollution peaked to 48 per cent on November 7.