Delhi AQI stays ‘very poor’ for 4th day, likely to deteriorate into ‘severe’

The 24-hour average AQI stood at 369 on Thursday, while 22 monitoring stations recorded severe air quality by 10pm, with PM2.5 as the main pollutant.

A thick haze covered the city on Thursday as the air quality index (AQI) remained in the “very poor” category for the fourth consecutive day, just days ahead of Diwali as forecast said of a likely deterioration to ”severe” levels from Friday

Stubble burning contributed 15.6% to Delhi’s PM2.5 levels on Thursday, with the share forecast to rise to 19.2% on Friday, according to the DSS. (Vipin Kumar/ HT)

The 24-hour average stood at 369 on Thursday, according to the Central Pollution Control Board (CPCB)’s 4pm bulletin, just 8 points lower than Wednesday’s 377. It was higher than 350 on Tuesday and 324 on Monday.

The CPCB classifies an AQI between 0 and 50 as ‘good’, 51-100 as ‘satisfactory’, 101-200 as ‘moderate’, 201-300 as ‘poor’, 301-400 as ‘very poor’ and 401-500 as ‘severe’.

Forecast and Monitoring Station Readings

The Air Quality Early Warning System (AQEWS) has forecast that Delhi’s air quality will remain “very poor” on Thursday before deteriorating to the “severe” category from Friday to Sunday. The outlook for the subsequent six days is also likely to remain between the two categories.

The main pollutant was PM2.5.

Sources of Pollution

The Decision Support System (DSS) for Air Quality Management in Delhi estimated the contribution of stubble burning to Delhi’s PM2.5 levels at 15.6% on Thursday with a forecast indicating that it would rise to 19.2% on Friday before dropping sharply to 1.6% on Saturday.

Meanwhile, the DSS, under the Ministry of Earth Sciences, estimated that the contribution of transport emissions, meanwhile, is expected to increase from 17.9% on Thursday to 18.3% on Friday and 21.1% by Saturday.

Nasa’s satellite detected 2,251 farm fires in Punjab and Haryana between October 1 and November 4 (2,025 in Punjab and 226 in Haryana), including 246 on November 4. During the corresponding period last season, it detected 2,579 fires.

However, HT had previously reported that Nasa’s satellite passes at about 1.30pm, and most burning now happens later in the day, so its count is far below the real number.