Delhi’s air quality improves to ‘poor’, light rain expected over 2 days

The overall average air quality index (AQI) in the national capital was at 234 on Sunday, according to the Central Pollution Control Board’s (CPCB) 4pm bulletin. On Saturday, the AQI in Delhi was 312, considered in the ‘very poor’ zone.

Strong winds helped flush out pollutants on Sunday, giving Delhi residents the cleanest air in four days as it helped improve the air quality to ‘poor’ levels, scientists said, adding that light rainfall over the next two days is expected to wash away pollutants and slightly bring down temperature.

Strong winds helped flush out pollutants on Sunday, giving Delhi residents the cleanest air in four days (Amal KS/HT PHOTO)

The overall average air quality index (AQI) in the national capital was at 234 on Sunday, according to the Central Pollution Control Board’s (CPCB) 4pm bulletin. On Saturday, the AQI in Delhi was 312, considered in the ‘very poor’ zone.

According to CPCB officials, air quality is likely to remain in the ‘poor’ band the next two days, although it may marginally dip on Monday, but will again improve within the same category till at least November 26. “As per input received from the weather agency, strong winds will help clear the air over the next two days,” said a senior CPCB official, who did not wish to be named.

The levels of PM 2.5 — the most harmful aerosols in Delhi’s air — also showed a downward curve from Saturday night, data showed. From 118 µg/m³ at 11pm on Saturday, the PM 2.5 levels in the city came down to 97µg/m³ at 6pm on Sunday. The safe limit of PM 2.5 levels is 60µg/m³.

Scientists at the India Meteorological Department (IMD) said this week Delhi is expected to have cleaner air on account of strong winds and light rainfall, adding that the minimum temperature is expected to drop around 4 degrees Celsius over the next five days.

On Sunday, the average wind speed was 15-16kmph, favourable for dispersion of pollutants.

“The wind speed may fall marginally on Monday to 10-12kmph, but it will pick up towards evening. The city could see a drizzle on Monday night and light rainfall on Tuesday, which is expected to further improve the air quality,” said Kuldeep Srivastava, head, regional weather forecasting centre, IMD.

The rain and gusty winds may result in a slight drop in the mercury, Srivastava said.

“On November 30, night temperature may drop to 11 degrees Celsius. On Sunday the maximum temperature was 26.8 degrees Celsius while minimum settled at 15.3 degrees Celsius, four notches above normal. The temperatures have remained on the higher side because of the Western Disturbance, which brings clouds,” he added.

“There could be a slight dip of one or two notches in both day and night temperatures on 29-30 November. However, it is not likely to fall sharply until December,” he said.

The System of Air Quality and Weather Forecasting and Research (SAFAR), the ministry of earth sciences’ (MoES) air quality forecasting wing also forecast that air quality will dip marginally on Monday, but will improve on November 26. “The share of crop stubble burning in Haryana and Punjab will also reduce over the coming days, as the harvest season is almost over while good winds will not allow smoke to travel to Delhi, said a senior SAFAR scientist.