Air quality in Delhi oscillated between the "poor" and "very poor" categories today due to local pollutants as authorities predicted further rise in the pollution level.
The Central Pollution Control Board (CPCB) recorded an overall AQI of 314, which falls in the "very poor" category.
An AQI between 0 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 is considered to be "severe".
The centre-run System of Air Quality and Weather Forecasting (SAFAR) said the air quality in the national capital is "very poor" and at present there is "insignificant intrusion (of pollutants) from outside of Delhi".
"It is an ideal time to ascertain the impact of local emissions on the pollution level of Delhi," it said.
Local emissions include pollutants from vehicles, construction activities and garbage burning, among others. Earlier, authorities had said that vehicular emissions contribute to 40 per cent of the air pollution in Delhi.
The CPCB said in 19 areas of the national capital the air quality was in the "very poor" category, while in six areas it was recorded in the "poor" category.
The PM2.5 (fine particulate matter in the air with a diameter of less than 2.5 micrometre) level was recorded at 174 and the PM10 level at 358, it said.
Ghaziabad and Noida recorded "very poor" air quality. In Faridabad and Gurgaon, the air quality was "poor" and "moderate" respectively, the CPCB data showed.
Delhi's air quality has been in the "very poor" category for the past one week but on Saturday it had improved to "poor" category for a brief period. It again slipped into "very poor" category Sunday, the authorities said.