Marginally better air in Delhi, AQI in ‘very poor’ zone

According to the air quality early warning system of ministry of earth sciences, the winds are likely to be coming from east-southeast direction of Delhi with a speed 10-18 kmph on Monday. There is likely to be light to moderate rain and thundershowers accompanied with gusty winds (20-30 kmph) and possibility of hailstorm at isolated places

Rain and strong winds helped improve Delhi’s air quality marginally on Sunday. The air quality index (AQI) on Sunday was 354 in “very poor” category, a marginal improvement from Saturday’s AQI of 443 in “severe” category. Scientists said that the air quality was likely to improve further on Monday and remain in “moderate” or “poor” category till January 9.

A morning walker near India Gate on a winter morning at Rajpath in New Delhi, India. (Biplov Bhuyan/HT PHOTO)

“The air quality is improving, but at a very slow pace because of high moisture levels. Pollution particles tend to become heavy and cling together when moisture levels are high. But we are expecting further improvement by tonight. More rain is expected and winds are likely to be strong for a week. So air quality is not likely to deteriorate significantly till January 9,” said VK Soni, scientist at India Meteorological Department’s air quality division.

An AQI of 201 to 300 is considered poor while an AQI of 301 to 400 is considered very poor and can cause respiratory illness in people on prolonged exposure.

According to the air quality early warning system of ministry of earth sciences, the winds are likely to be coming from east-southeast direction of Delhi with a speed 10-18 kmph on Monday. There is likely to be light to moderate rain and thundershowers accompanied with gusty winds (20-30 kmph) and possibility of hailstorm at isolated places. The ventilation index is likely to be 5000 m2/s on January 4. The wind speed on Sunday was around 15 to 20kmph.

The ventilation index is a function of the mixing height and the wind speed and defines the ability of the atmosphere to disperse pollutants. A ventilation index below 2,350 sq metres/second is considered poor. Mixing height is the height at which pollutants mix in the air.

Ghaziabad, Greater Noida, Faridabad, Hisar, Noida, Narnaul, Meerut and Moradabad also recorded “very poor” category air even after the rains while Lucknow’s AQI was in severe category on Sunday.