The contribution of stubble burning in neighbouring States to the daily levels of PM2.5 – a chief pollutant – in Delhi was as high as 48% on November 7 and averaged 33.5% during the week after Deepavali (November 5-11). This is the same period when air pollution spiked in the Capital, National Capital Region and several other north Indian States.
The average contribution of stubble burning to Delhi’s PM2.5 level in November was 14.6%, according to data from the government-run monitoring agency SAFAR (System of Air Quality and Weather Forecasting and Research).
The highest contribution of stubble burning to PM2.5 in Delhi for a day was 58% in 2018, 43% in 2019, and 46% in 2020, said Gufran Beig, founder project director of SAFAR.
After initial confusion on November 15, Solicitor General Tushar Mehta, representing the Central Government, had told the Supreme Court on November 17 that the contribution of farm fires to Delhi’s PM2.5 count was about 35% to 40% in October and November. The annual contribution is usually far lesser since the burning of stubble is only a seasonal activity and not all year round.
The effect of stubble burning on pollution in Delhi and NCR has been a political hot potato with the Delhi Government blaming neighbouring States for the hazardous dip in air quality during winter.
Two spells
Delhi usually experiences two spells of high air pollution during winter, one in October-November and the other in December-January.
“During October-November, one of the main reasons for the high pollution in Delhi and NCR is stubble burning,” said Mr. Beig.
But the stubble burning season is over before the second spell in December-January. For instance, the contribution of stubble burning to PM2.5 in Delhi has already come down to 1% on November 30, as per SAFAR data, and number of farm fires have also dwindled.
“During the second spell, the main reason for air pollution is the transport of pollutants from the rest of the Indo-Gangetic Plain to Delhi combined with extreme cold and foggy conditions,” said Mr. Beig.
He said this year, the number of effective fire counts in October-November (the stubble burning season) according to SAFAR data is around 77,000, the highest in four years.
