Delhi’s air quality deteriorated again Sunday and slipped into very poor category due to local pollutants as authorities predicted further increase in pollution level.

According to the Centre-run System of Air Quality and Weather Forecasting (SAFAR), the overall air quality index (AQI) of Delhi was 322, which fell 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 SAFAR had last week forecast that the air quality of the national capital is expected to “significantly deteriorate” Sunday due to a decline in temperature which might lead to entrapment of pollutants. However, even after “significant deterioration” the air quality is likely to stay in the ‘very poor’ level, it had said.

According to SAFAR, the air quality is very poor in Delhi and at present there is “insignificant intrusion from outside of Delhi”.

“It said it is an ideal time to ascertain the impact of local emissions on the pollution level of Delhi,” it said.

The local emissions include pollution from vehicles, construction activities and garbage burning among others.

Earlier, authorities had said that vehicular emissions contribute to 40 per cent pollution in Delhi.

The Central Pollution Control Board (CPCB) said in 14 areas of the national capital, the air quality was in the “very poor” category, while in 14 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 155 and the PM10 level at 328, it added.

Ghaziabad recorded very poor air quality, Faridabad poor air quality and Gurgaon recorded moderate air quality, 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 of time. It again slipped into very poor category Sunday, the authorities said.

According to SAFAR, the air quality is very poor in Delhi and at present there is “insignificant intrusion from outside of Delhi”.

“It said it is an ideal time to ascertain the impact of local emissions on the pollution level of Delhi,” it said.