With a layer of smog continuing to envelope the national capital city in the morning hours on Tuesday, the overall air quality further dipped under the very poor category.

According to the System of Air Quality and Weather Forecasting And Research (SAFAR), the city's overall Air Quality Index (AQI) was recorded at 346 in the very poor category this morning. The concentration of both PM 2.5 and PM 10 in the environment was recorded at 346 and 237 respectively under the very poor and poor category respectively on Tuesday.

As per the SAFAR forecast, the city's air quality will further deteriorate with AQI escalating to 359 in the very poor category on Wednesday.

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 at 341, 306 and 344 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, doctors say.

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 438 with PM 2.5 concentration at 438 and the PM 10 concentration at 319 under severe and very poor category respectively.

Gurugram's overall air quality also further deteriorated to the very poor category as the AQI was reported at 316, with PM 2.5 concentration at 316 and the PM 10 concentration at 173 both under very poor and moderate category on this morning.