Delhi's air quality deteriorates; authorities predict further rise in pollution levels

Delhi's air quality further deteriorated Tuesday and was recorded in the 'very poor' category, with the authorities predicting a rise in pollution levels over the next two days.

The overall air quality index (AQI) of the national capital stood at 355, which falls in the 'very poor' category, the Central Pollution Control Board (CPCB) data showed.

An AQI between 100 to 200 comes under 'moderate' category, 201 and 300 is considered 'poor', 301 and 400 'very poor', while that between 401 and 500 is 'severe'.

According to the Centre-run System of Air Quality and Weather Forecasting (SAFAR), the overall air quality of Delhi slipped into the 'very poor' category on Monday and the pollution level was expected to rise further.

"The feeble western disturbance lies over the northern part of India at a height of 3.1 km above mean sea level. These western disturbances influence may further deteriorate Delhi's air quality by introducing additional moisture and making the air heavy," the SAFAR said.

"Levels of both gaseous and particulate pollutants are likely to increase in the next two days, and then decline. The AQI for the upcoming two days is forecast to be in the upper level of 'very poor'," it said.

The overall PM2.5 level (fine particulate matter in the air with a diameter of less than 2.5 micrometer) was recorded at 190 and the PM10 level at 335, the SAFAR said.

On Tuesday, while the Jahangirpuri, Mundka and Nehru Nagar areas saw severe pollution levels, 30 places in the national capital recorded 'very poor' category air quality, the CPCB said.

Neighbouring Ghaziabad, Faridabad and Noida recorded 'very poor' air quality, while in Gurgaon it was in the 'poor' category, it added.

According to the Indian Institute of Tropical Meteorology, the maximum ventilation index on Tuesday was 3,500 sqm/second.

A ventilation index lower than 6,000 sqm/second with an average wind speed of less than 10 kmph is unfavourable for dispersion of pollutants.