IIT-D predicted pollution spike a month ago Layer of cloud and smoke play foul
IIT report warned Centre, Delhi government in the first week of Oct that an increase in stubble burning would push the air quality to hazardous levels between November 1 and November 15
NEWDELHI: The Indian Institute of Technology (IIT), Delhi, in its bimonthly forecast meant to allow authorities to prepare an effective action plan to combat air pollution in the national capital, warned the Union and Delhi governments in the first week of October that an increase in stubble-burning would push the air quality in the region to hazardous levels between November 1 and November 15.
In the report to the Central Pollution Control Board (CPCB) accessed by HT, the IIT scientists said, “Stubble burning will remain a primary pollution contributor, along with Delhi’s own sources. Control of unpaved roads, industrial emissions and plying of heavy commercial vehicles (HCVS) in sensitive zones will be important.”
Scientists at Iit-delhi said that stubble burning in the neighbouring states of Punjab and Haryana was forecasted as a “background concentration” to the ultra-fine PM2.5 particulate matter in the city.
This means that even if all the local sources of pollution in Delhi are completely shut down, emission from crop residue burning in the neighbouring states will keep the city’s air quality in the “poor zone”.
But with the Centre, and the state governments of Delhi, Punjab and Haryana unable to act on the warning to control farm fires, data from System of Air Quality and Weather Forecasting and Research (SAFAR), affiliated to the Union ministry of earth sciences, shows that the contribution from stubble-burning in Delhi’s air on November 1 was 46%. On Tuesday, when the Air Quality Index (AQI) of Delhi was 425, according to the CPCB’S 4pm bulletin, the share of farm fires on Delhi’s PM levels was nearly 25%.
Till Monday, 48,155 cases of stubble burning were reported from Punjab, and 5,920 from Haryana . Along with the slow speed of winds at the ground level in Delhi, the change in wind direction from easterly to northwesterly has been carrying the toxic smoke from parts of Punjab and Haryana to the Capital.
Iit-delhi’s Centre of Excellence for Research on Clean Air was mandated this January to create bimonthly action plans for CPCB to help the agency - and by extension the Union and state governments - to identify the most polluted areas and the key sources likely to cause air quality to worsen over the fortnight, so that pre-emptive action can be taken.
Mukesh Khare, professor at Iit-delhi and coordinator of the Centre of Excellence for Research on Clean Air, said that even though CPCB was being informed of the air quality forecast in advance, effective action was not possible on ground mainly because of the lack of coordination between the agencies.
“The effectiveness of this is ultimately on the implementation. Even CPCB has to depend on enforcement agencies to act on time. For instance, to control road dust (water) sprinkling has to happen at the right time but that is the job of the municipalities,” Khare said.
According to IIT-D’S analysis, if pre-emptive measures were effectively implemented, the pollution levels in Delhi could have been brought down by about 20%. The Environment Pollution (Prevention and Control) Authority (Epca) had also implemented a slew of measures under the Graded Response Action Plan (Grap) from October 15 this year. However, despite these plans, there has been no major improvement in the air this year -- leading to several experts questioning the effectiveness of Grap and describing it as “reactive” rather than “pro-active”
A senior CPCB official, who asked not to be named, said that, being a central body, it has to rely on state governments and local civic bodies to implement the action plan.
“CPCB cannot go around every road with water tankers and sprinkle water. We need cooperation from agencies, only then the forecast system will yield the desired results,” the official said.
Delhi’s environment minister Kailash Gahlot said that the Centre and the state governments of Punjab and Haryana are not serious about controlling the problem of farm fires.
“Even if they did not pay heed to warnings, at least they could have done something when the fires actually began. They are not doing anything. I have written letters to the Union environment ministers and the chief ministers of Punjab and Haryana to help distribute harvesting machinery to farmers, which will automatically control this problem,” said Gahlot.
“Everything that was advised under IIT’S action plan was communicated to respective governments and a lot of work was done on the ground. The issue of air pollution should not politicised,” said Bhure Lal, chairperson EPCA.
D Saha, former head of the air quality lab of CPCB, said Delhincr was receiving around 37% transported dust, apart from local dust generated due to poor land use planning, congestion and improper traffic management. “The administrative and regulatory measures are not uniform. Nothing can be achieved in isolation. Experts, government agencies and people — everyone has a role to play,” Saha said.
NEWDELHI: A toxic combination of clouds and smoke was responsible for Tuesday’s pollution as it blocked off the sunlight. The lack of heat, in turn, traped pollutants and worsened the air quality, weather experts said.
Adding to the factors was low wind speed and a temperature drop, both not conducive to the dispersal of pollutants.
Explaining the various factors, scientists at India Meteorological Department (IMD) said there was a thick layer of cloud over Delhincr from a passing western disturbance. Also, the smoke carried in from the raging farm fires in the states of Punjab and Haryana did not help matters.
Both blocked the sunlight and trapped pollutants.
“There was a double layer of cloud and smoke (from various sources of pollution) in the atmosphere, which blocked off the sunlight. Cloud cover is on account of a passing western disturbance. The sunlight on Tuesday was lesser than that the previous day. Deficient sunlight does not allow the surface to warm up, which allows the pollutants to remain trapped,” Kuldeep Srivastava, head, IMD, said.
The situation is likely to remain the same for the next three or four days, he said. The wind speed is likely to remain low over the next few days. Also, cloud cover combined with shallow fog and haze is expected on Wednesday as well.
However, the maximum and minimum temperatures are likely to rise by a point each.
According to IMD, the night temperature dropped to 11.7 degrees Celsius, two notches below the season’s average. Also, the day temperature was recorded a notch below normal at 28 degrees Celsius. On Monday, the minimum temperature was 13.5 degrees Celsius while maximum was 28.5 degrees Celsius.
“When the air is colder, it becomes heavier and, hence, unfavourable for dispersion of pollutants,” Srivastava explained.
Also, IMD scientists said shallow fog resulting in high moisture content during the morning hours added to making the air heavier, and thus increasing its capacity to trap pollutants.
Besides that, low wind speed could not disperse pollutants as well.
The wind speed was 7-8kmph, which again is not enough to disperse pollutants.
A consistent wind speed of around 15-20kmph is required for clearing pollutants.
“When sunlight is restricted and there is another layer of pollutants, the vertical movement of air, which helps in dispersion, is reduced. The low mixing height (boundary layer) allows accumulation of pollutants. Also, since the wind direction is northwesterly, it is bringing in smoke from stubble burning,” a senior Central Pollution Control Board (CPCB) official, who did not wish to be named, said.
Delhi’s air quality started to deteriorate from Monday night when the concentration of pollutants in the air breached the severe level. The spike continued to Tuesday and by evening, the levels of PM 2.5 — the most harmful aerosols in Delhi’s air — breached the ‘emergency’ mark of 300ug/m3.the safe limit of PM2.5 is 60ug/m3.
Over the past few days, the air quality had been fluctuating between ‘very poor’ and ‘poor’ levels. On Tuesday, the air quality index (AQI) plunged to 425 in the ‘severe’ zone. Before that, the AQI had touched ‘severe’ on November 4 (407). Delhi saw the worst pollution since November 2016 on November 3, when the AQI was 494.