A thick layer of pollutants continued to engulf the national capital as the air quality remained in the ‘severe’ category for the fourth consecutive day.

The overall air quality index (AQI) of the city was recorded at 460 (severe) at 7am– a rise from 415, which was recorded at 4pm on Saturday, and no respite is expected from the toxic air at least until Novermber 7, according to the Central Pollution Control Board (CPCB).

Some areas in the city and also showed air quality in the ‘hazardous’ category, with the maximum at Wazirpur (633).

Based on thresholds set under the Graded Response Action Plan (Grap), an average AQI beyond 450 is enough to invoke ‘severe plus’ or stage 4 category measures.

To address the deteriorating air quality, the Commission for Air Quality Management (CAQM)– the committee for invoking actions under the Grap, is likely to convene a meeting today to decide on Grap measures.

The measures under Stage 4 include a complete ban on entry of trucks into Delhi, stopping construction activities in Delhi, including linear projects like highways and roads, a ban on plying of Delhi registered diesel medium good vehicles and heavy goods vehicles and a ban on light commercial vehicles outside Delhi (unless essential).

It also gives states and the centre discretion on whether they need to allow employees to work from home, ban physical classes for higher grades and even if they wish to implement the odd-even scheme.

Delhi’s 24-hour average AQI has been over 400 since 5pm on Thursday now, with forecasts showing this is likely to continue till at least November 7, with no significant change expected in the meteorological conditions.

“Delhi’s air quality is likely to remain in the ‘severe’ category from Sunday to Tuesday (Nov 7). The outlook for the subsequent six days shows the air quality is likely to remain in ‘severe’ to ‘very poor’,” said the Early Warning System (EWS) for Delhi – a forecasting model under the ministry of earth sciences and used by CAQM.

IMD data showed real-time visibility at Palam was down to 400 metres at 7am this morning.

Of the 32 functioning air quality stations at 7am on Sunday, 31 were in the ‘severe’ category.

The highest AQI was recorded at Wazipur (633), followed by Shadipur (492), Dwarka (490) and the Karni Singh Shooting Range (490). The AQI in Punjabi Bagh was at 510, at Mundka 547, 411 in ITO, at 430 in Lodhi Road, and 499 in Okhla, among others, at 7am.

The IMD has also said Delhi’s wind direction, both locally and at the transport level – is northwesterly. This is likely to help stubble intrusion into the capital, at a time when farm fires are fairly rampant across northwest India, particularly Punjab.

Punjab has now recorded over 1,000 fires for a fourth consecutive day. Though showing a declining trend, Indian Agricultural Research Institute (IARI) data showed Punjab recorded 1,360 farm fires on Saturday. The daily count was at a season-high 1,921 fires on Wednesday, 1,668 fires on Thursday and it was 1,551 on Friday.