New Delhi, Dec 22 : The air quality in Delhi dipped to the 'severe' category on Friday, prompting the Commission for Air Quality Management (CAQM) to invoke Graded Response Action Plan (GRAP) stage-III. The Anand Vihar station was in the 'severe' category with PM 10 at 500 and PM 2.5 also at 492, while the NO plunged to 133, and CO reached 115, both in 'moderate' category, as per the Central Pollution Control Board (CPCB). At the Bawana station, PM 2.5 reached 453 and PM 10 to 448, both in the severe category, while the CO reached 94 and NO2 to 60, in 'satisfactory' levels. In Dwarka Sector 8, the PM 10 reached 427, in 'severe' category, PM 2.5 was at 396, in 'very poor' category, while CO was at 122, in 'moderate' levels. The air quality at the Indira Gandhi International Airport T3 area was 'very poor' with PM 2.5 recorded at 333 and PM 10 at 217, both in 'poor' category, while CO plummeted to 103, under 'moderate' category, while NO2 was at 54, in 'satisfactory' levels. At the ITO station, the PM 2.5 plunged to 499 and PM 10 was to 457, both in 'severe' category, while NO2 spiked to 138, and CO to 144, both in the 'moderate' category. The PM 2.5 and PM 10 at Jahangirpuri were recorded at 500, placing both under the 'severe' category. Here, carbon monoxide was at 121 in 'moderate' levels, while NO2 reached 201, in 'poor' category. The PM 2.5 at Okhla Phase-II was recorded at 443, while PM 10 reached 451, placing both under the 'severe' category. The NO2 reached 207, in 'poor' category, while CO was at 160, in the 'moderate' category. Notably, the AQI between zero and 50 is considered 'good'; between 51 and 100 'satisfactory'; between 101 and 200 'moderate'; between 201 and 300 'poor'; between 301 and 400 'very poor'; and between 401 and 500 'severe'. /IANS