The air quality of the national capital on Thursday dipped to "severe" category as the over all Air Quality Index (AQI) of the city stood at 418, according to data from the System of Air Quality and Weather Forecasting And Research (SAFAR).

The PM 2.5 and PM 10 concentration stood at 418 and 399, respectively, under the same "severe" and "very poor" category, according to the SAFAR data.

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, the AQI of Delhi's neighbouring cities of NOIDA stood at 498 under "severe" category with PM 2.5 concentration at 498 and the PM 10 concentration at 397 under "very poor" category, while Gurugram's AQI was reported at 393 under the "very poor" category with PM 2.5 concentration at 393 and the PM 10 concentration at 327 under the "very poor" category.

The severe category of air quality calls for health warnings of emergency conditions and even serious risk of respiratory effects on the general public.

For any sensitive persons, the SAFAR advises them to remain indoor and also keep activity indoors at low levels, while for asthmatic persons, the relief kit should be kept ready while the air quality continues under the severe category.

In Pusa, the AQI recorded 445 "very poor" category, while PM 10 was reported at 396 under "very poor" category and PM 2.5 concentration 445 under "severe" category.

At Lodhi Road, the Air Quality Index was reported 388 with PM 2.5 concentration at 388 under the "very poor" category and the PM 10 stood at 329.

The Air Quality Index at the city's Mathur Road was also under the "severe" category at 431 with PM 10 concentration at 414 under the "very poor" category.

According to SAFAR, the air quality of the city will deteriorate further under "very poor" category with AQI at 431 under "severe category" and the PM 10 concentration at 399 under "very poor" category on Wednesday.