After the Commission for Air Quality Management (CAQM) invoked Stage-IV restrictions of the Graded Response Action Plan (GRAP) under ‘Severe+’ (above 450 AQI) in Delhi and adjoining areas, the air quality index (AQI) improved in the morning to 424 which falls under ‘severe’ category (400-450 AQI) at 9 AM Wednesday. The AQI was 452 at 9 pm on Tuesday.

The CAQM announcement on GRAP IV came Sunday evening only after Delhi’s daily average AQI rose to 457 at 7 PM from 441 at 4 PM. Several pollution control measures, including shifting of classes in schools to online mode and ban on truck entry came into force from 8 AM November 18.

At 8 AM, out of 39 spots where air quality is monitored the maximum AQI was 465 at Mundka whereas the lowest was 278 at Lodi Road, which is monitored by Pune-based IITM, according to data of Central Pollution Control Board (CPCB). But the AQI monitored by India Meteorological Department at same Lodi Road shows 382.

Sources said that the GRAP IV curbs may stay for some more days, depending on how fast the air quality improves.

IMD has said that the visibility at 5.30 am was 1 km at IGI airport, 500 metre at Safdarjung airport in Delhi. But in some places in Uttar Pradesh, the visibility was very poor in the morning. Kanpur had zero visibility, Lucknow had 50 meter and Bareilly 200 meter, IMD said. In Amritsar, Chandigarh and other places in the north, the visibility was above 500 meter.

The weather bureau has predicted ‘dense to very dense’ fog conditions very likely to prevail over Punjab, Haryana-Chandigarh during late night of November 21 to early morning of November 24. It also has said that dense fog conditions are very likely to prevail in night/morning hours in Punjab, Haryana, Uttar Pradesh till November 21 and in Himachal Pradesh till November 22.

IMD’s forecast for Delhi during Wednesday says a clear sky, which means no rains. It also said the predominant surface wind is likely to be from north-west direction with speed less than 08 kmph

during morning hours when smog/moderate to dense fog is also likely to be seen. “The wind speed will increase thereafter becoming less than 10 kmph from during afternoon. It will decrease thereafter becoming less than 06 kmph during evening and night. Smog/ shallow fog is likely in the evening/night,” IMD said.

The CAQM has classified the air quality under four stages: Stage 1 - ‘poor’ (AQI 201-300), Stage 2 - ‘very poor’ (AQI 301-400), Stage 3 - ‘severe’ (AQI 401-450) and Stage 4 - ‘severe plus’ (AQI above 450) and accordingly restrictions have been prescribed for each stage.

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