With stronger winds, Delhi’s air quality saw slight improvement on Saturday with an AQI of 291, while the national capital also recorded the first ‘cold day’ of this season.
On Friday, the AQI was 329, in the ‘very poor’ category.
The India Meteorological Department (IMD) predicted a ‘cold day’ for Delhi on Saturday and Sunday. A ‘cold day’ is recorded when the minimum temperature at a station in the plains is less than or equal to 10 degrees Celsius, and the maximum temperature at the station is 4.5 to 6.4 degrees less than normal.
On Saturday, the maximum temperature at the Safdarjung weather observatory was 17.8 degree Celsius, 5 degrees below the normal of 22.5 degrees Celsius. The minimum temperature recorded on Saturday at Safdarjung was 6 degrees Celsius, the lowest so far this season, and two degrees below the normal for this time of the year. The weather observatories at the Ridge and Aya Nagar both recorded a minimum temperature of 5 degrees Celsius on Saturday.
According to the IMD, parts of Delhi-NCR witnessed strong northwesterly cold winds on Saturday with a speed of around 10-20 kmph during the first half of the day. Wind speed increased to around 25 kmph and later 40 kmph in the afternoon.
The Delhi airport saw shallow fog on Friday morning, though strong winds and low moisture have not been favourable for dense fog episodes, according to scientists at the IMD.
The minimum temperature on Sunday is predicted to be 5 degrees Celsius, while the maximum is likely to be 18 degrees Celsius.
Cold wave conditions are likely to persist over Punjab, Haryana and north Rajasthan over the next three days, the IMD forecast said.
Along with an increase in wind speed recorded at most monitoring stations on Saturday, the concentration of particulate matter fell. At the Jawaharlal Nehru Stadium monitoring station, the wind speed increased from 2.3 m/s at 9 pm on Friday to 5.2 m/s at 2 pm on Saturday, going by data from the Delhi Pollution Control Committee. The PM10 level at the station fell from 259 µg/m3 at 9 pm on Friday to 172 µg/m3 by 3 pm on Saturday. The PM2.5 concentration saw a steeper fall, from 182 µg/m3 at 9 pm on Friday to 81 µg/m3 by 3 pm on Saturday. The 24-hour standard for PM2.5 is 60 µg/m3, while the standard for PM10 is 100 µg/m3.
The Jawaharlal Nehru Stadium monitoring station recorded a 24-hour average AQI of 291 at 5 pm on Saturday. AQI between 201 and 300 is considered ‘poor’. The monitoring stations at Chandni Chowk, Lodhi Road, Mandir Marg and Aya Nagar recorded AQI in the ‘poor’ category on Saturday. At ITO and RK Puram, the stations recorded AQI in the ‘very poor’ category – between 301 and 400.
The SAFAR forecast issued on Saturday indicates that the AQI is likely to remain in the ‘poor’ category on Sunday, but could deteriorate to ‘very poor’ on Monday due to reduced ventilation.