Winds keep minimum low as Delhi logs best air since October 19

Delhi experienced its cleanest air day since October last year, with an average air quality index (AQI) of 147 (moderate) on Tuesday. The improvement in air quality was attributed to bright sunshine and strong winds. The India Meteorological Department (IMD) forecasts that pollution levels will continue to drop over the next two days due to strong surface winds. The Early Warning System (EWS) also predicts that air quality will remain in the moderate category for the next three days. The minimum temperature in Delhi is expected to hover around 7°C.

Bright sunshine and strong winds throughout the day on Tuesday helped Delhi record its cleanest air day since October last year, even as the minimum temperature plunged by nearly five degrees.

At Netaji Subhas Chandra Bose canopy at India Gate in New Delhi on Tuesday. (Raj K Raj/HT Photo)

The Capital clocked a 24-hour average air quality index (AQI) of 147 (moderate) at 4pm on Tuesday, an improvement from 180 a day ago, and the lowest since October 19 last year, when pollution gauges read just 121.

The air was helped by a gusty breeze that also brought in chilly winds from the northwest and pushed the minimum temperature down to 7°C, a sharp drop from 12.4°C a day ago.

The maximum on Tuesday, meanwhile, settled at 21°C — the same as Monday, two notches below normal.

Pollution levels are likely to drop even further, with the India Meteorological Department (IMD) forecasting that strong surface winds will continue to course through the city over the next two days.

“Wind speeds averaged around 10-15kmph during the day. This is likely to increase further on Wednesday and Thursday, hovering between 20-30kmph,” said Kuldeep Srivastava, scientist at IMD.

Forecasts by the Early Warning System (EWS) for Delhi, an air quality forecasting model under the ministry of earth sciences, shows similar air quality is also expected over the next three days.

“Delhi’s air quality is likely to be in the ‘moderate’ category from Wednesday till Friday. The outlook for the subsequent six days shows air quality is likely to be between ‘moderate’ and ‘poor’,” said EWS in its daily bulletin on Tuesday.

According to Srivastava, Delhi logged a dip in its minimum due to relatively clear skies, but a sharp drop in mercury is unlikely in the coming days.

“These strong winds will not allow night-time temperatures to dip sharply. For a really low minimum, one needs clear skies and calm winds. The minimum is likely to hover around 7°C over the next three days too,” he said.

Srivastava said Delhi recorded moderate fog on Tuesday, with the visibility briefly dropping to 200m at Palam. Only shallow to moderate fog is likely in the coming days, he added.