Delhi’s air quality continues to hover around ‘severe’ category

The air quality index (AQI) of the national capital improved marginally on Friday morning, as compared to the previous evening, but continued to hover around the “severe” category.

An AQI between 401 and 500 is considered to be “severe” and between 301 and 400 belongs to the “very poor” category.

The AQI recorded on Friday morning bordered around 400, while that of Thursday evening was 450, which was in the “severe” category.

An AQI above 400 can affect healthy people and seriously impact those with existing diseases, according to the Central Pollution Control Board (CPCB).

On Wednesday, a layer of smoke and pollutants had built up over Delhi-national capital region (NCR) due to thousands of stubble fires raging in neighbouring Punjab and local emissions such as traffic and fire crackers.

The layer had built up because wind speed had reduced significantly restricting dispersal of pollutants. Similar conditions persisted on Thursday, but the visibility had improved marginally because of a wind speed of around 8 kilometres per hour (kmph).

However, the layer of smog settled back in the evening after the wind speed dipped.

Stubble fires contributed to 42% of Delhi’s particulate matter (PM 2.5) load on Thursday, which was the highest this season, according to the System of Air Quality and Weather Forecasting and Research under Indian Institute of Tropical Meteorology (IITM), a Pune-based scientific institution.

“There are two things that are occurring simultaneously. North-westerly winds are bringing pollutants, while wind speed has vastly reduced. On Wednesday night and Thursday early morning, the wind was calm. As a result, pollutants remained trapped close to the surface. On Thursday morning, the wind speed picked up after 9:30 am for a while, but became calm by the evening. We are not expecting a change in wind direction before November 10, when it may gradually shift to easterly. However, during the transition of wind direction, usually wind speed falls, which may further worsen the air quality in Delhi-NCR and other towns in north-west India,” said Kuldeep Shrivastava, head, regional weather forecasting centre.

Other towns in north-west India such as Bahadurgarh, Bulandshahr, Ghaziabad, Greater Noida, Kanpur, Moradabad and Lucknow also recorded AQI in the “severe” category.

The minimum temperature recorded in Delhi till 6:30 am on Friday was 11.9 degrees Celsius (C), 3 degrees C below normal. The minimum temperature will be updated again at 8:30 am.

In Delhi-NCR, the bursting of firecrackers has gone up because of the upcoming festival of Diwali, which will be celebrated on November 14.

However, the Delhi government has announced a ban on fire crackers this Diwali.