Local emissions, weather push air to ‘very poor’ zone
While the farm fires in neighbouring states of Haryana and Punjab have drastically reduced — it contributed just 4% to Delhi’s PM 2.5 levels on Tuesday, according to System for Air Quality and Weather Forecasting and Research — the national capital’s air quality plunged further to the upper end of the very poor zone of the air quality index (AQI) on Tuesday.
According to government agencies, it is likely to remain there throughout the week owing to the wind speed calming down and wind patterns changing in the coming days.
As per the Central Pollution Control Board (CPCB), the AQI on Tuesday was 367, even worse than Monday’s 318, though both are in the very poor category. On a scale of 0 to 500, an AQI value between 300 and 400 is considered very poor, and those above 400 are considered severe.
The air quality continued to deteriorate further Tuesday evening, with most of the hot spots slipping into the ‘severe’ zone. By 9pm, 11 of the 35 monitoring stations recorded severe air quality — Anand Vihar (414), Ashok Vihar (437), Bawana (413), DTU (409), Jahangirpuri (443), Mundka (413), Nehru Nagar (404), Patparganj (410), Punjabi bagh (405), Rohini (414) and Vivek Vihar (425).
The CPCB, which is in charge of implementing the Graded Response Action Plan (Grap), said it is taking measures to control local pollution levels.“We are monitoring the situation closely. Measures under the very poor zone are already being enforced. Patrolling teams are carrying field inspections regularly,” said a senior CPCB official.
Despite repeated attempts, MM Kutty, chairperson of the Commission for Air Quality Management (CAQM) in NCR and adjoining areas, could not be reached for a comment.
Scientists at the India Meteorological Department (IMD) said the average wind speed during the day reduced to 7-8 kmph from 10-12 kmph on Monday. “The wind speed will further reduce from December 4 or 5 and the direction is likely to change to easterly, from the present north-westerly. Whenever there is a change in pattern, winds turn calm and trap pollutants,” said Kuldeep Srivastava, head of IMD’s regional weather forecasting centre.
He said easterly winds are also likely to bring in moisture, which when combined with calm winds allow pollutants to accumulate. There is also a forecast of shallow fog on December 4 or 5. “Besides, the change in wind pattern will also lead to a rise in minimum temperature between December 4 and 7,” Srivastava further said.
On Tuesday, the Safdarjung Observatory — the official marker for the city’s weather — recorded a minimum temperature of 8.1 degrees Celsius, two notches below normal. The maximum settled at 27.2 degrees Celsius, two notches above normal.
Sagnik Dey, associate professor, IIT-Delhi, said, “In October and November, farm fires contribute about 25% to the overall pollution in Delhi. In December, we record the same pollution level even without stubble burning because of reduced dispersion of pollutants,” Dey said.
Anumita Roychowdhury, executive director, Centre for Science and Environment (CSE), said at present, the only factors at play are meteorological and local pollutants. “Even though there has been a declining trend in the overall pollution levels since 2017, Delhi still has to reduce its PM 2.5 concentrations at least by 60% to mitigate these peak episodes. Also, on-ground monitoring of waste burning and emissions from illegal industries need to be stepped up to have some real impact,” she said.