Delhi stays trapped under high pollution, dense fog

While the day started with AQI in the ‘very poor’ category, with the 24-hour average recorded at 390 at 4 pm, by 9 pm it had crossed 400, registering at 403 at 10 pm. AQI has been trending upwards since upwards since December 25, when strong winds ended a 13-streak of ‘very poor’ and ‘severe air’.

The Capital remained trapped under a combination of dense fog and high levels of pollution on Sunday, with the forecasts showing no sign of respite for residents. Delhi’s air quality index (AQI), which had been slowly deteriorating over the pastthree days, entered the ‘severe’ category.

Delhi AQI crossed 400 by 9pm (RAJ K RAJ /HT PHOTO)

While the day started with AQI in the ‘very poor’ category, with the 24-hour average recorded at 390 at 4 pm, by 9 pm it had crossed 400, registering at 403 at 10 pm. AQI has been trending upwards since upwards since December 25, when strong winds ended a 13-streak of ‘very poor’ and ‘severe air’.

However, with two straight ‘poor’ days recorded, there has been a steady deterioration in the AQI, with the 4 pm 24-hour average reading at 332 (very poor) on Friday and 385 (very poor) Saturday.

The Commission for Air Quality Management (CAQM) official said the body was monitoring the situation and a meeting of the Graded Action Plan (GRAP) sub-committee would likely be called if it worsens. “No meeting is scheduled as of now. If the AQI keeps rising by Monday morning, a meeting may be convened,” the official said.

At present, Stage-3 measures — which ban private construction and plying of BS-3 petrol and BS-4 diesel vehicles in Delhi — are already in place across the national capital region (NCR). For Grap-4 restrictions, which were lifted on December 24, the AQI would need to cross 450

Central Pollution Control Board (CPCB) data through the day on Sunday showed at least 20 out of the 39 active ambient air quality stations in the ‘severe’ range at different times during the day. The worst impacted locations included Anand Vihar (451) and Shadipur (451).

Despite the unfavourable weather conditions, forecasts by the Centre’s Air Quality Early Warning System (EWS) for Delhi had earlier said the city would continue in the ‘very poor’ category till December 31. “The outlook for the subsequent six days from January 1 shows the AQI is likely to be in the ‘very poor’ and ‘severe’ category’ ranges,” the EWS had further said in its daily bulletin on Sunday.

Meanwhile, on Sunday, as a result of low wind speeds in the region, with a thick layer of fog visible across the Indo-Gangetic plains, satellite imagery showed. Weather experts said dense fog is likely to persist till the end of the year, continuing fog-related disruptions to the aviation sector and even delaying trains. On Sunday, stations with zero visibility included Pathankot, Agra, Amritsar, Gwalior and Kanpur.

In Delhi, Safdarjung recorded dense fog with the lowest visibility recorded at 100 metres at 8 am, only shallow fog (500 metres) was recorded at Palam – the reference weather station for Delhi’s Indira Gandhi International (IGI) airport, where over 400 flights were delayed and three were cancelled.

The India Meteorological Department (IMD) has issued an orange alert for Monday and a yellow alert for Tuesday. Under the prevailing western disturbance that began on December 27, dense to very dense fog is likely on Monday and isolated dense fog on Tuesday.

A second, more active western disturbance is then expected from December 30 onwards – possibly bringing light rain to the northern plains, including over Delhi on January 1, making it a wet start to the new year.

“The next western disturbance impacting around December 30 should be more active. It will start impacting the plains from December 31 and so there are chances of very light to light rain across the plains, including Delhi on January 1. We can also expect winds to remain low - so the AQI won’t improve significantly,” said Mahesh Palawat, vice president at Skymet.

In its national weather bulletin, the IMD said dense to very dense fog conditions are very likely to continue over Himachal Pradesh, Punjab, Haryana-Chandigarh and West Uttar Pradesh till December 31 and East Uttar Pradesh till January 1 – with reduction thereafter.

“Dense fog conditions also likely during night and morning hours at isolated pockets over East Madhya Pradesh, Arunachal Pradesh till December 29; and over pockets of West Bengal, Bihar, Assam & Meghalaya, Nagaland, Manipur, Mizoram & Tripura and Odisha till January 1,” it said.

Meanwhile, Delhi’s minimum stood at 6.3°C on Sunday, which was a degree below normal. It was 7.8°C a day earlier. The maximum stood at 22.2°C, which was two notches above normal and 0.1°C lower than Saturday. The maximum is forecast to hover between 21-23°C till December 30 – possibly rising by another couple of degrees on December 31. The minimum is expected to remain between 6-8°C and hover between 7-9°C till the end of the year.