Numbers make you breathe easier? Delhi AQI improves to 377 as winds push it out of ‘severe’ zone

NEW DELHI: The wind came to the rescue of Delhiites. It picked up towards late night on Saturday and continued blowing throughout Sunday, resulting in the blanket of fog thinning and the air quality improving a bit.

The air quality index (AQI), which entered the severe category on Saturday evening — it had been recorded at 409 at 8pm — was at 377 (very poor) at 4pm on Sunday.




Though it had initially been predicted that the index will remain in the severe range (above 400 on a scale of 500) on Sunday and Monday, the Centre's Air Quality Early Warning System for Delhi later said the air quality is likely to hover within the very poor band until Wednesday.

Central Pollution Control Board's data showed that out of 39 active air quality monitoring stations in Delhi, the AQI was above 400 at 13 stations on Sunday. Ayanagar was the lone one to record a poor reading (293).

Though the city experienced moderate fog, 107 flights were cancelled and 500 delayed at Delhi's IGI Airport due to low visibility at several other airports across north India.

Unlike most of Saturday, when calm conditions prevailed, easterly winds of up to 6 to 10 kmph started blowing into the city from 11.30 pm on Saturday and continued till 6.30 am on Sunday. Its speed was between 4 and 8 kmph during the daytime. "As wind speed increased, it prevented the air quality from slipping into the severe range and also thinned the layer of fog," said an official.

Palam reported the lowest visibility of 300 metres from 10 pm on Saturday to 12.30 am on Sunday, India Meteorological Department (IMD) said, adding the visibility improved to 600m thereafter.

At Safdarjung, the city's base station, the lowest visibility was 200m from 1.30 am to 2.30 am before it improved to 500m at 5.30 am. The visibility at IGI Airport was above 1,000m from 12.30 pm to 7 pm, said R K Jenamani, senior scientist, IMD. In contrast, most parts of Delhi recorded lower visibility of around 200 to 800m during Sunday.

The Met department issued a yellow alert (be aware) for moderate fog at most places and dense fog at isolated areas in the city in the early morning hours of Monday. Moderate to shallow fog is likely from Tuesday to Thursday.

Though IMD earlier forecast that ‘cold day' conditions was likely to prevail in isolated areas in Delhi, no station met the criterion on Sunday. Safdarjung (16.9 degrees Celsius) and Palam (16.3) reeled under cold day conditions on Saturday.

A ‘cold day' is declared in Delhi when the minimum temperature is below 10 degrees C and the departure of maximum from the normal is 4.5 notches or more.

As the sun briefly came out on Sunday, the day temperature gradually started rising. The maximum was recorded at 18.1 degrees C, four notches below normal, compared to 16.9 degrees C on Saturday. The day temperature is expected to rise to around 20-22 degrees C on Monday.

The minimum temperature stood at 9.4 degrees C, one notch above normal. It was 6.1 degrees C a day ago. The minimum is likely to remain around 9 degrees C on Monday.