Low wind speed, dip in temperature pushes Delhi’s air to ‘severe’ category
The change in the wind direction from easterly to northwesterly also played a part in pushing Delhi’s air quality across the danger mark. The northwesterly wind carrying crop stubble burning residue from the neighbouring states of Punjab and Haryana has been blowing into the city.Updated: Nov 12, 2019 09:07 IST
Delhi’s air quality worsened on Tuesday morning to cross the ‘severe’ mark to reach 408 after being in the ‘very poor’ category on Monday. Scientists at the India Meteorological Department (IMD) said that low wind speed and the dip in temperature was to blame for this.
The average air quality index (AQI) at 6.40 am on Tuesday was 408. The overall AQI according to the Central Pollution Control Board (CPCB) on Monday evening was 360.
“The average wind speed dropped from 20kmph on Sunday to nearly 10kmph on Monday. The winds remained calm through the night, which made the situation worse,” a scientist at IMD said on Tuesday.
Experts said that the air pollution levels will remain in the higher end till Wednesday, after which the wind speeds are expected to pick up for at least three days, till Sunday.
The change in the wind direction from easterly to northwesterly also played a part in pushing Delhi’s air quality across the danger mark. The northwesterly wind carrying crop stubble burning residue from the neighbouring states of Punjab and Haryana has been blowing into the city. This change in the wind direction has not been bringing in pollutants but also cold winds from the snow-clad Himalayan mountains. When the air is colder, it becomes heavier and thus unfavourable for the dispersion of pollutants.
According to SAFAR’s forecast, on Tuesday the share of stubble burning in Delhi’s PM 2.5 (fine particulate matter with diameter less than 2.5 micrometres) levels is likely to touch 25%.
Delhi environment minister Kailash Gahlot on Monday wrote to the chief ministers of Punjab and Haryana urging them for immediate action to stop stubble burning in their states.
Speaking to the media, Gahlot said that he also wrote to Union environment minister Prakash Jaavdekar over the issue and expressed displeasure as the meeting called by the Centre on November 9 on air pollution was not attended by the environment ministers from Haryana, Rajasthan, Uttar Pradesh and Punjab.
“The major reason for the air pollution in the national capital is the stubble burning in the neighbouring states. Despite the Supreme Court’s intervention, the environment ministers of the four states did not attend the meeting,” Gahlot said.