The national capital’s overall air quality inched closer to the severe category on Thursday morning as pollution levels rose sharply after a marginal reduction, primarily due to calm winds and spike in farm fires.
The central government’s Air Quality Early Warning System for Delhi said a significant increase in the number of fire points was observed over Punjab (around 3,000), Haryana and Uttar Pradesh on Wednesday which is likely to impact the air quality of Delhi-NCR and other parts of northwest India.
Delhi recorded an air quality index (AQI) of 397 at 11 am on Thursday. The 24-hour average AQI was 297 on Wednesday, 312 on Tuesday, 353 on Monday, 349 on Sunday, 345 on Saturday and 366 on Friday.
An AQI between 0 and 50 is considered ‘good’, 51 and 100 ‘satisfactory’, 101 and 200 ‘moderate’, 201 and 300 ‘poor’, 301 and 400 ‘very poor’, and 401 and 500 ‘severe’
A senior scientist at the India Meteorological Department (IMD) said the wind speed dipped on Wednesday which allowed accumulation of pollutants.
Following slight relief, the air quality again entered the ‘very poor’ category by the evening, he said.
PM10 levels in Delhi-NCR stood at 420 microgram per cubic meter (µg/m3) at 10 am, the highest this season so far, according to CPCB data.
PM10 levels below 100 µg/m3 are considered safe in India.
NASA’s satellite imagery showed a large, dense cluster of fires that covered most parts of Punjab and some regions of Haryana.
Stubble burning
According to the Ministry of Earth Sciences’ air quality monitor, SAFAR, the share of stubble burning in Delhi’s PM2.5 concentration was 18 per cent on Wednesday.
It was 23 per cent on Tuesday, the maximum this season so far, 16 per cent on Monday, 19 per cent on Sunday and 9 per cent on Saturday.
Also read | Centre promises law to check stubble burning
SAFAR said accumulation of locally generated pollutants and increased external intrusion due to north-north westerly boundary level winds from regions where stubble is burnt will be major factors for the increase in PM2.5 levels.
According to IMD, the predominant wind direction was northerly and the maximum wind speed was 8 kilometers per hour. The minimum temperature was recorded at 12.5 degrees Celsius - the lowest in this season so far.
On Wednesday, Delhi Environment Minister Gopal Rai said only green firecrackers can be manufactured, sold and used in the national capital.
He also said the Delhi government will launch an anti-firecracker campaign from November 3 and requested people not to burn crackers considering the seriousness of the situation due to the COVID-19 pandemic.