While 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, the Central Pollution Control Board (CPCB) recorded an overall AQI of 297 which is in the 'poor' category.
Delhi's air quality oscillated between 'poor' and 'very poor' categories on Sunday due to local pollutants as authorities predicted further rise in the air pollution level.
While 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, the Central Pollution Control Board (CPCB) recorded an overall AQI of 297 which is in the '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.
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 16 areas of the national capital, the air quality was in the "very poor" category, while in 12 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 162 and the PM10 level at 345, it said. Ghaziabad and Greater 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 of time. It again slipped into "very poor" category Sunday, the authorities said.
According to SAFAR, in the next two days the air quality would deteriorate and be in the upper level of "very poor".
(With PTI inputs)
