New Delhi, Jan 4 : Days after GRAP-III was lifted as the AQI slightly improved and entered into 'very poor' levels, the air quality in the national capital on Thursday afternoon again deteriorated with several monitoring stations entering into 'severe' category. The air quality at Anand Vihar plummeted in the 'severe' category with PM 2.5 at 428 and PM at 433 while the NO2 reached 103, in the 'moderate' category while NO2 was at 68 or 'satisfactory', as per the Central Pollution Control Board (CPCB). The Air Quality Index (AQI) at ITO also remained in 'severe' category with PM 2.5 reaching at 447 and PM 10 at 403. The CO was recorded at 79 or 'satisfactory'. The particulate matter (PM) 2.5 at Punjabi Bagh also reached 441 while PM 10 was at 407, both in the 'severe' category. The air quality at Jahangirpuri air quality monitoring station also entered into 'severe' category with PM 2.5 at 466 and PM 10 444. The Carbon Monoxide (CO) was also reached at 101 or 'moderate'. The PM 2.5 at Okhla Phase-II was recorded at 411 and PM 10 at 405 both in the 'severe' category. The CO was at 106, in the 'moderate' levels. At Mundka the AQI remained in the 'severe' category with PM 2.5 at 401 and PM 10 at 303, in the 'very poor' 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'. However, at Bawana, the air quality was in the 'very poor' category with PM 2.5 at 375 and PM 10 at 282, in the 'poor' category. The AQI monitoring station at Dwarka sector 8 recorded PM 2.5 at 400 and PM 10 was at 321, both in the very poor category. The AQI at the Indira Gandhi International (IGI) airport station plummeted with PM 10 at 377, in the very poor category while PM 2.5 was at 288, in the poor levels. The CO was recorded at 21, or 'good'. /IANS