Delhi's air quality turns 'severe'; mercury again plunges to 4 deg C

NEW DELHI: Delhi's air quality deteriorated to 'severe' category on Saturday as a cover of smog surrounded the national capital and prevented dispersion of pollutants, authorities said. Meanwhile, this is the second time in three days that the mercury has plunged to 4 degrees Celsius –the lowest temperature in the last four years.

This is a fourth time in this season when the air quality here has worsened to severe category. The first time it dipped to the severe category this year was just two days before Diwali.

A day after Diwali, which fell on December 7, the air quality again slipped to severe category on November 8. The third time it slipped into severe category was December 12.

The overall air quality index (AQI) of the city stood at 408, which falls in the 'severe' category, the Central Pollution Control Board (CPCB) data showed.

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

Twenty-five areas of the national capital recorded severe air quality while 11 recorded very poor air quality, the CPCB said.

In Delhi, the overall PM2.5 level –fine particulate matter in the air with a diameter of less than 2.5 micrometre –was recorded at 290 and the PM10 level at 458, the CPCB said.

In the National Capital Region, Ghaziabad recorded the worst air quality at an AQI of 451. Noida recorded severe air quality while Faridabad's pollution level remained in the very poor category, the CPCB said. The Centre-run System of Air Quality and Weather Forecasting (SAFAR) said the air quality might improve over the next two days but would still remain in the very poor category.

Unfavourable weather conditions and prevalence of a thick smog cover are further worsening the conditions and preventing dispersion of pollutants, authorities said.