New Delhi, Nov 8 (IANS): Recent satellite imagery released by NASA has exposed the alarming spread of toxic smoke enveloping Delhi, raising concerns among experts who are now referring to it as a looming air pollution "crisis" in the nation's capital.

NASA Worldview's visuals unveiled a thick blanket of smog shrouding the northern plains of India on Monday, with air quality deteriorating to unhealthy levels in several cities surrounding Delhi.

The air quality in Delhi on Wednesday morning continued to be in 'severe' category with several stations across the city recording a rise in PM 2.5 and carbon monoxide (CO).

In neighbouring Ghaziabad the air quality index ( AQI) was at 382, Gurugram at 370, Noida at 348, Greater Noida at 474, and Faridabad 396 on Wednesday.

In the national capital, the Anand Vihar station remained in the ‘severe' category with PM 2.5 at 500 while the CO was at 112 and NO2 at 128, under 'moderate' category, as per the Central Pollution Control Board (CPCB).

The Bawana station recorded PM 2.5 and PM 10 at 500 (severe) while the CO reached 110 (moderate).

At Delhi Technical University (DTU) station, the PM 10 reached 456 under 'severe' category while PM 2.5 was at 356 under ‘very poor’ category. The CO was recorded at 115, under the 'moderate' category.

The station at Dwarka sector 8 recorded PM 10 at 465 and PM 2.5 at 457 (‘severe'), while CO was at 135, under moderate category.

The 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'; and 401 and 500 'severe'.