Farm fires down, but pollution continues to peak in Delhi
Experts have blamed the dip in the capital’s air quality mainly on local factors such as construction and road dust, and garbage burning that need to be reined in urgently.Updated: Oct 16, 2019 23:24 IST
Delhi’s air slipped into the “very poor” category on Wednesday for the first time since July although the meteorological department said smoke from stubble burning in the northern states of Punjab and Haryana was not yet blowing into the city and NASA scientists reported fewer cases of farm fires in the region from September 25, when harvesting began in these states.
Experts blamed the dip in the capital’s air quality mainly on local factors such as construction and road dust, and garbage burning that need to be reined in urgently.
System for Air Quality and Weather Forecasting and Research (SAFAR) — the ministry of earth sciences’ weather and air quality monitoring system —showed that only 5% of the PM 2.5 levels recorded in Delhi came from stubble burning emissions on Wednesday. PM (particulate matter) 2.5 is the most critical pollutant in Delhi’s air. It can penetrate deep inside the lungs and affect public health adversely.
The forecast shows that on Thursday and Friday too, the contribution from stubble burning in the neighbouring states will remain low at between 5% and 7%. Farmers in Punjab and Haryana traditionally set fire to the residual stalks to clear their fields for the next sowing season after harvesting the last crop around this time of the year.
Scientists at the Indian Meteorological Department (IMD) said that the pollutants from crop residue burning in Punjab and Haryana was not reaching Delhi yet because of easterly winds.
“The winds are easterly at the moment. But atmospheric conditions are calm and stable. We had expected pollution levels to improve, but it didn’t because there is no dispersal,” said VK Soni, senior scientist at IMD.
According to a weather official, there may be some relief on Friday. “Air quality in Delhi may improve on Friday, when a Western Disturbance is likely to occur in the national capital region bringing thunderstorm and very light rain, which may wash down pollutants here,” said, Kuldeep Srivastava, head, regional weather forecasting centre (RWFC), India Meteorological Department (IMD).
Pollutants from stubble burning zones in Haryana and Punjab travel to Delhi only when the wind direction is westerly or north-westerly. IMD said the wind direction is likely to remain easterly for the next few days.
Scientists at the US space agency NASA also said that an analysis of stubble burning trends this year shows fewer cases of farm fires had been reported from September 25 until October 10, compared to previous years.
Fires from stubble burning observed so far through satellite images are at the lowest level since 2013, said Hiren Jethva, research scientist, Universities Space Research Association (USRA) at NASA’s Goddard Space Flight Centre .
“Half of October gone, fire activity is at minimum compared to that in 2013 and 2018. PM 2.5 (fine particulate matter released by burning) at the US Embassy in New Delhi remains relatively lower but getting poorer as fires are picking up in northwest crop fields,” Jethva tweeted on Wednesday.
The Haryana Pollution Control Board (PCB) too noted that when compared to 2018, cases of crop residue burning had gone down “marginally”, despite the harvest beginning early this year. In 2018, between September 25 and October 16, at last 1,250 cases of stubble burning had been reported. This year, however, only 1,217 such cases were reported during the same period.
“Last year, we could reduce the size of the burnt area by 25% and this time we hope it will come down further,” said S Narayanan, member-secretary, Haryana PCB.
In Punjab, between September 25 and October 15, nearly 750 stubble burning cases have been reported.
The lack of farm fires could also be explained by a delay in harvesting this year, since the monsoon withdrawal was late.
Back in Delhi, experts insisted that stubble burning in the northern states was only one factor contributing to pollution in the capital.
“Crop fires are episodic, it will happen for a month. Though stubble burning is a contributor, we need to remember that local contributors are the worst. When you look ahead, controlling the local sources of pollution is the biggest challenge that we face,” said Sunita Narain, a member of the Supreme Court-mandated Environment Protection (Prevention and Control) Authority (EPCA).