Air quality in the national capital remained in the 'very poor' category on Sunday but the contribution of stubble burning to Delhi's air came down by two per cent, authorities said.
Ministry of Earth Sciences' forecast body SAFAR said the city's Air Quality Index (AQI) was recorded as 350, which falls in the 'very poor' category with PM2.5 as the lead pollutant.
It said that though light showers will bring some respite, the air quality will again deteriorate from Tuesday due to poor ventilation conditions.
"Since wind direction is mainly from eastern side and moderate rain is expected, the AQI will improve significantly and touch moderate category for Monday and then again degrade to poor category for next two days.
"The SAFAR effective fire count was observed as 815 but as winds are not favourable and rain is expected, the stubble contribution today will be just two per cent, down from 14 per cent yesterday," it said.
According to the Decision Support System (DSS), developed by the Indian Institute of Tropical Meteorology, Pune, approximately 2-12 per cent contribution in PM2.5 over Delhi is likely from biomass burning on Sunday and this contribution will decline significantly on Monday owing to easterly winds.
It said that the lower wind speed and low mixing layer height were inhibiting dispersion along with moderate stubble intrusion.
According to the data from the Indian Agricultural Research Institute (IARI), there were just 14 farm fires in Punjab and no such incident was recorded in Haryana and Rajasthan.
Uttar Pradesh had 39 incidents of farm fires, while Madhya Pradesh had only one fire. In a steep rise on October 15 and 16, as many as 1,948 farm fires were recorded compared to 1,795 incidents which occurred in an entire month till October 14.
On October 16 alone, a total of 741 crop residue burning incidents were recorded, out of which Punjab recorded 429, Haryana had 176, UP had 121, Rajasthan had two and Madhya Pradesh had 13 fires.
A total of 4,092 burning events were detected between September 15 and October 16 which are distributed as 2,375, 1,026, 581, 0, 27 and 83 in Punjab, Haryana, UP, Delhi, Rajasthan and MP, respectively.
"Overall, the total burning events recorded in the six states are 41.4 per cent less than in 2020 till date. Punjab recorded 55.3 per cent reduction, Haryana recorded 31.1 per cent increase, UP recorded 70.4 per cent increase, Delhi recorded 100 per cent reduction, Rajasthan recorded 87.4 per cent reduction and MP recorded 76.9 per cent reduction, in the current season than in 2020," said the IARI.
Stubble burning in neighbouring states significantly contributes to the air pollution in Delhi.
The active fire events due to rice residue burning were monitored using satellite remote sensing following the new "Standard Protocol for Estimation of Crop Residue Burning Fire Events using Satellite Data".
Punjab had recorded 1.02 lakh incidents of stubble burning in 2016. The number decreased to 67,079 in 2017; 59,684 in 2018 and 50,738 in 2019 from October 1 to November 30. The state logged 79,093 such incidents last year, according to the IARI.
Haryana saw 15,686 farm fires in 2016; 13,085 in 2017; 9,225 in 2018; 6,364 in 2019 and 5,678 in 2020. Punjab and Haryana attract attention during the paddy harvesting season in October and November.
Farmers set their fields on fire to quickly clear off the crop residue before cultivating wheat and potato. It is one of the main reasons for the alarming spike in pollution in Delhi-NCR.