Delhi: Fog, poor wind speed keeps air very poor

According to IMD scientists, moderate fog was observed during the early morning hours at the Safdarjung Observatory (the official marker for the city’s weather) as well as at the Palam weather station, with the visibility being reduced to less than 300 metres.

Delhi witnessed early morning fog for the second consecutive day on Tuesday even as pollution levels remained high due to favourable weather conditions, India Meteorological Department officials said.

Delhi recorded an overall air quality index (AQI) value of 383, in the very poor zone on Tuesday. (Sanchit Khanna/HT Photo)

According to IMD scientists, moderate fog was observed during the early morning hours at the Safdarjung Observatory (the official marker for the city’s weather) as well as at the Palam weather station, with the visibility being reduced to less than 300 metres. On Monday, the city saw the season’s first dense fog with the visibility dropping to zero at Palam.

Delhi recorded an overall air quality index (AQI) value of 383, in the very poor zone on Tuesday. However, air quality at several monitoring stations such as Vivek Vihar, Anand Vihar, Narela, Jahangirpuri, Nehru Nagar, Punjabi Bagh was in the severe range (an AQI value of 400 and more).

“The high moisture content, which was a result of the easterly winds, started to reduce on Tuesday and hence the intensity of fog cover was less. We expect ‘moderate’ fog in Delhi over the next three to four days. Though moisture has reduced, the wind speed did not pick up much and therefore no significant improvement was seen in the air quality,” said Kuldeep Srivastava, head of IMD’s regional weather forecasting centre.

On Tuesday, the minimum temperature was 9.5 degrees Celsius, a notch above normal. The maximum settled at 28.3 degrees, four notches above normal.

As per System for Air Quality and Weather Forecasting and Research (Safar), the union ministry’s air quality forecasting wing, the share of stubble burning in the city’s PM 2.5 levels was negligible. “The major factors influencing Delhi’s air quality at present include reduced ventilation index and fog formation. Air quality is likely to remain in very poor category over the next two days,” the Safar bulletin stated.