Delhi’s air quality stays ‘severe’, IMD forecasts further drop in temperature this week

Central Pollution Control Board (CPCB) data showed that Delhi’s overall AQI on Wednesday was 433, up from 418 on Tuesday.

Air quality in the national capital continued to remain in the ‘severe’ zone for the second consecutive day on Wednesday as low winds and falling temperatures kept pollution levels high. India Meteorological Department (IMD) has forecast a marginal improvement in the air quality on Thursday, but the air quality index (AQI) is likely to remain in the early end of the ‘severe’ zone.

A man and child seen in warm clothes on a winter day at Connaught Place in New Delhi. (Sanchit Khanna/HT PHOTO)

Central Pollution Control Board (CPCB) data showed that Delhi’s overall AQI on Wednesday was 433, up from 418 on Tuesday.

In view of the deteriorating air quality in Delhi, the CPCB on Wednesday held a review meeting where they announced a slew of precautionary measures to prevent any further rise in pollution levels, including order hot-mix plants and stone crushers in Delhi to stay shut till January 2.

The pollution monitoring body also ordered agencies concerned to increase the frequency of mechanised sweeping in all major roads and also directed agencies to step up dust mitigation measures.

Senior CPCB officials said that even though the overall AQI has been in the ‘severe’ zone for two consecutive days now, but measures under the Graded Response Action Plan (Grap) will not be put in place in unless the levels of PM2.5 (ultrafine particulate matter with diameter less than 2.5 micrometres) consistently remain above the 300ug/m3 mark and PM10 (particulate matter with diameter less than 10 micrometres) remains above the 500ug/m3 mark for 48 hours.

At 7pm on Wednesday, it was 17 hours since PM 2.5 levels were above the 300ug/m3 mark, but PM10 levels were below the 500ug/m3 mark.

Scientists said the pollution levels were higher because of low wind speed and the temperature, which was trapping the pollutants closer to the ground.

VK Soni, head of IMD’s environment monitoring and research centre, said that the wind speed did not pick up during the day which led to the accumulation of pollution particles.

“The wind speed was largely calm through Wednesday, which led to an accumulation of pollutants closer to the surface. The forecast says that the AQI will remain in the severe zone on Thursday too,” Soni said.

Soni added, “The prominent pollutant has been PM 2.5, the contribution of larger particles has been less, in the pollution over the last few days, has been.”

He added that there is a possibility of marginal improvement in wind speed from December 25, which bring down the high levels of pollution.

Meanwhile, the temperature will also continue to drop over the coming days in Delhi and the neighbouring cities.

IMD recordings show that on Wednesday the minimum temperature at the Safdarjung observatory, which is considered the official recording for the city, was 4 degree Celsius. This was four degrees below the season’s normal. The maximum temperature was 23.3 degree Celsius, two degrees above normal.

At the Palam observatory, the minimum temperature was 7.1 degree Celsius, while in Ayanagar, it was 5 degree Celsius.

IMD scientists said the minimum temperature is likely to remain the same on Thursday and start falling again from Friday.