New Delhi, Nov 21 (IANS) A layer of smog blanketed Delhi on Thursday morning, as the air quality index (AQI) was at 389 at 7.15 a.m., falling into the "very poor" category. However, some areas continued to have severe air pollution levels.

According to the Central Pollution Control Board (CPCB) data, in 12 areas of Delhi, the AQI level remained between 400 and 500. It was 408 in Alipur, 405 in Anand Vihar, 414 in Ashok Vihar, 418 in Bawana, 401 in Dwarka Sector 8, 435 in Jahangirpuri, 413 in Mundka, 411 in Nehru Nagar, 407 in Punjabi Bagh, 407 in Rohini, 412 in Shadipur, and Wazirpur remains at 436 level.

Whereas in 26 areas of the national capital, the AQI level remained above 300 and between 400. It was 369 in Aya Nagar, 339 in Chandni Chowk, 343 in Mathura Road, 368 in Dr Karni Singh Shooting Range, 360 in DTU, 370 in IGI Airport, 341 in Dilshad Garden, 365 in ITO, 354 in Jawaharlal Nehru Stadium.

At Lodhi Road the air pollution level was 335, Major Dhyanchand Stadium 372 and Mahendra Marg 365. The levels were 366 in Najafgarh, 395 in Narela, 356 in North Campus DU, 365 in NSIT Dwarka, 389 in Okhla Phase 2, 381 in Patparganj, 365 in Pusha, 389 in RK Puram, 373 in Siri Fort, and 394 in Sonia Vihar.

An AQI is considered "poor" between '200 and 300', "very poor" at '301 and 400', "severe" at '401-450," and 450 and above is "severe plus."

On Wednesday, the AQI was registered under the "severe" category and slightly improved in several areas on Thursday.

The Supreme Court on Monday asked the Delhi government as to how the ban on bursting firecrackers in the national capital to curb air pollution was flouted during Diwali celebrations.

The Delhi government last week implemented stringent measures to curb pollution under Stage 3 of the Graded Response Action Plan (GRAP), in addition to the actions under Stage 1 and Stage 2 - which were invoked on October 15 and October 22 respectively.

Under GRAP 3, private BS III petrol and BS IV diesel vehicles have been banned. According to the government, violators will face penalties under Section 194(1) of the Motor Vehicle Act, 1988, which translates to a fine of Rs 20,000.

Apart from the high air pollution levels in Delhi, a thick froth of toxic foam continued to float in sections of the Yamuna River near Kalindi Kunj and Okhla Barrage, raising concerns.