Delhi's air quality deteriorated to the 'severe' category Saturday as a thick smog engulfed the national capital and prevented dispersion of pollutants, authorities said.
This is the fourth time this season that the air quality in the city has worsened to the 'severe' category. The first time the air quality dipped to this category this year was just two days before Diwali.
A day after Diwali, which fell on November 7, the air quality again slipped to the 'severe' category. The third time it slipped into this category was on December 12.
The overall air quality index (AQI) of the city stood at 421, which falls in the 'severe' category, 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-eight areas of the national capital recorded 'severe' air quality, while seven recorded 'very poor' air quality, the CPCB said.
Officials said they are closely monitoring the situation and if the conditions prevail for 48 hours then stringent action which include emergency measures like odd-even car rationing scheme, would be taken.
A ban on construction activities might be enforced if "severe" pollution level persists for 48 hours, the officials 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 296 and the PM10 level at 466, the CPCB said.
In NCR, 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 overall air quality over Delhi entered in the 'severe' zone this morning and is expected to remain in the same range until Sunday afternoon. It would then decline slowly and may touch the 'very poor' category.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)