New Delhi, Nov 27 : A dense and noxious haze, commonly known as smog, enveloped Delhi on Monday, with the air quality plummeting to the 'severe' category at several monitoring stations across the national capital. The Anand Vihar station was in the 'severe' category with PM 10 at 421 and PM 2.5 also at 421, while the ozone plunged to 190 in the 'moderate' category and CO was at 95, in 'satisfactory' level, as per CPCB. At the Bawana station, PM 2.5 reached 432, in the 'severe' category and PM 10 at 366, in the 'very poor' category, while the CO reached 94, in 'satisfactory' levels and NO2 at 28, in the 'good' category. In Dwarka sector-8 station, the PM 2.5 reached 425 and PM 10 was at 405, both in the 'severe' category while CO was at 110, in 'moderate' level. The air quality at the Indira Gandhi International Airport T3 area was 'very poor' with PM 2.5 recorded at 372 and PM 10 at 316 while the CO plummeted at 111, under 'moderate' category and NO2 was at 20, in 'good' levels. At ITO station, the PM 2.5 plunged to 500 and PM 10 was at 435, both under 'severe' category while the NO2 spiked to 290, in the 'poor' category. The PM 2.5 at Jahangirpuri was recorded at 451 and PM 10 reached 435, placing both under the 'severe' category. Here, the carbon monoxide was 82 in 'satisfactory' level and NO2 at 18, in the 'good' category. PM 2.5 at Okhla Phase-II was recorded at 427, while PM 10 reached 418, placing both under the 'severe' category. The NO2 reached 107, in moderate 'category' and CO was at 92, in the 'satisfactory' levels. Notably, 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'. /IANS