New Delhi, Dec 3 : With a layer of smog enveloping the capital city early on Saturday, the overall air quality continued in "very poor" category giving Deliites no respite from the toxic air. According to the System of Air Quality and Weather Forecasting And Research (SAFAR), the city's overall Air Quality Index (AQI) was recorded at 323 in the "very poor" category this morning. The concentration of both PM 2.5 and PM 10 in the environment was recorded at 323 and 211 respectively under the "very poor" and "poor" category respectively. As per the SAFAR forecast, the city's air quality is set to further deteriorate with AQI escalating to 335 in the "very poor" category on Sunday. Notably, 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". The air quality index at Pusa, Lodhi Road, and Mathura Road were recorded 312, 315 and 342 respectively in the "very poor" category this morning as per the SAFAR system. The prolonged exposure to "poor category" air quality may lead to respiratory illness. However, the overall Air Quality Index of Delhi's neighbouring cities of Noida further deteriorated into the "severe" category and the air quality index was recorded at 379 with PM 2.5 concentration at 379 and the PM 10 concentration at 236 under "very poor" and "poor" category respectively. While Gurugram's overall air quality deteriorated further to "very poor" as the AQI was reported at 315, with PM 2.5 concentration at 315 and the PM 10 concentration at 171 both under the very "poor" and "moderate" category this morning. /IANS