Moderate fog today as well; Delhi’s AQI in poor category

Though moisture has reduced, the wind speed did not pick up much, therefore, no significant improvement was seen in the air quality

The fog spell that has been enveloping the city for the past two days is likely to continue on Wednesday, with lesser intensity, according to the India Meteorological Department.

The fog was much denser, also because of the increase of concentration of pollutants in the air at Delhi-Noida border, on Tuesday. (File photo)

Scientists said that even though moderate fog is expected on Wednesday, the air quality remained in the very poor zone. Central Pollution Control Board (CPCB) data shows that at 6am, the average air quality index of Delhi was 355.

The average air quality index (AQI) was 383 in the very poor zone on Tuesday. It was 400, almost touching the severe mark on Monday. On a scale of 0-500, an AQI value between 301-400 is considered very poor while 401-500 is severe. At least 10 of the 35 monitoring stations, including hot spots, however, continued to be in the severe category.

“The high moisture content, which was an impact 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, therefore, no significant improvement was seen in the air quality,” said Kuldeep Srivastava, head of IMD’s regional weather forecasting centre.

He added that no major variation is expected in the air quality over the coming week. The average wind speed on Tuesday was 5-6 kmph, not favourable for dispersion of pollutants.

“The wind speed is likely to remain around 10 kmph over the next three days. Also, Delhi may see very light rain or drizzle on December 11 on account of a Western Disturbance that will affect the whole of northwest India, including Delhi. Till at least December 12, there will be no significant change in the morning and night temperatures,” said Srivastava.

On Tuesday, the minimum temperature was 9.5 degrees C, a notch above normal. The maximum settled at 28.3 degrees C, 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 to 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.