The air quality in Delhi improved from 'very poor' to 'poor' category on Wednesday with favourable wind and rains in adjoining states.
The overall air quality index (AQI) of Delhi was 256 at around 8:30 pm on Wednesday, down from the high of over 500 in parts of Delhi earlier this month, according to the Union Earth Sciences Ministry's air quality monitoring service SAFAR. The average AQI was 372 on Tuesday, 354 on Monday, and 381 on Sunday.
There has also been a considerable drop in emissions in farm fires in adjoining states of Delhi, which have been a significant contributor to Delhi's poor quality. Though fires in Punjab continued unabated, seeing almost a three-fold rise in 24 hours. Farm fires in Punjab increased from 605 on Tuesday to 1,778 on Wednesday.
The AQI on Wednesday —256— is the lowest since October 20 when it was 232. For November, it was the best AQI since November 29, 2020, when it was 231, according to data from the Central Pollution Control Board (CPCB).
An AQI between 201-300 is considered 'poor', 301-400 'very poor', and 401-500 'severe'.
The improvement in air quality was evident from better visibility levels with 1,400 metres at the Palam airport and 1,500 at the Safdarjung airport in the morning. A smoky haze had lowered the visibility levels to 800 metres at these places on Tuesday.
A Met official said south-easterly winds gusting up to 30 kmph barrelled through parts on Tuesday night. It helped improve the situation.
Delhi recorded a minimum temperature of 16.9 degrees Celsius, three notches above normal. The maximum temperature settled at 30.2 degrees Celsius.
VK Soni, the head of the India Meteorological Department's (IMD) Environment Monitoring and Research Centre, said parts of east Rajasthan such as Alwar, Bhiwadi and Rewari and some areas in Haryana reported sporadic rains under the influence of a western disturbance affecting the hilly region in the north.
"The rainfall reduced the share of pollutants from these adjoining areas in Delhi's pollution," said Soni.
Favourable wind speed —10-18 kmph— is predicted to bring a considerable improvement in the air quality from November 11.
The Commission for Air Quality Management (CAQM) may also convene a meeting on Thursday to review the situation and revoke the curbs in Delhi-National Capital Region (NCR) under stage 3 —very poor air quality— of the Graded Response Action Plan (GRAP).
Though farm fires almost tripled in Punjan in the 24-hour-period, their share in Delhi's PM2.5 pollution dipped from 9 per cent on Tuesday to 5 per cent on Wednesday, according to data from the Indian Agricultural Research Institute and SAFAR.
The Delhi government had on Monday decided to reopen primary classes from November 9 and revoke the order asking 50 per cent of its staff to work from home in view of "improvement" in the city's air quality over the last few days.
However, BS-III petrol and BS-IV diesel four-wheelers were asked to stay off roads in Delhi under stage 3 of GRAP. Violation of the ban could invite a fine of Rs 20,000. Vehicles deployed for emergency services, and government and election-related work are exempted.
The Delhi government will run 500 additional buses in the capital under the "Paryavaran Bus Sewa" campaign to bolster public transport in a bid to reduce vehicular emissions.
According to a study conducted by The Energy and Resources Institute in 2018, vehicular emissions account for around 40 per cent of the PM 2.5 pollution in the capital.
With air pollution falling in Delhi, the CAQM on Sunday directed authorities to lift the ban on plying of non-BS VI diesel light motor vehicles in the region and the entry of trucks into the capital imposed under the stage 4 of the GRAP.
It had also banned construction work in public projects such as highways, flyovers, power transmission, and pipelines in Delhi-NCR.
The CAQM order recommending the restrictions was issued on Thursday.
According to an analysis conducted by the Delhi Pollution Control Committee (DPCC) last year, people in Delhi breathe the worst air between November 1-15 when stubble burning peaks and winters set in.
The Air Quality Life Index (AQLI) released by the Energy Policy Institute at the University of Chicago (EPIC) in June showed that residents of Delhi stand to lose 10 years of life expectancy due to poor air quality.
(With PTI inputs)