New Delhi, With PM10 as the lead pollutant, Delhi yet again faces a high pollution event in a modest pollution season resulting in the Air Quality Index (AQI) slipping to "very poor" category on Wednesday.

In fact, some stations even recorded "severe" AQI.

An AQI between zero and 50 is considered "good", 51 and 100 "satisfactory", 101 and 200 "moderate", 201 and 300 "poor", 301 and 400 "very poor", then between 401 and 500 is considered "severe".

"As part of Westerly Disturbances, there was a convective storm in the North-West part of India, including Delhi, which has been confirmed from satellite image/s. Due to this, the highly gusty winds led to high dust emissions having origin in Delhi and surrounding Haryana areas, resulting in the 'very poor' category of AQI," Gufran Beigh, founder project director of SAFAR said.

"This episode is likely to subside by tonight but relief is predicted to be short lived as another convective dust system is developing under persisting WD in the desert area of Rajasthan adjoining Delhi, which is going to be relatively of large scale and AQI may go back to very poor from Thursday evening for two days, unless sufficient pre-monsoon showers occur. But that seems unlikely," he said.

At 1.00 p.m, the AQI at Anand Vihar in east Delhi was (444), Ashok Vihar in north Delhi was (356), Chandani Chowk in Old Delhi (438), Dwarka sec 8 in west Delhi (433), Mandir Marg in central Delhi (336), IGI Airport in southwest Delhi (354), Lodhi Road (286) and Siri Fort in south Delhi (328), according to Central Pollution Control Board (CPCB).