Delhi Air Quality Index: Delhi's air quality deteriorated further. (File0
A thick blanket of fog shrouded Delhi on Friday, lowering visibility to 50 meters and affecting traffic movement, the India Meteorological Department said.
Dense fog reduced visibility to 50 meters at Safdarjung and Palam, it said. According to the India Meteorological Department (IMD), "very dense" fog is when visibility is between 0 and 50 metres. In case of "dense" fog, visibility is between 51 and 200 metres, "moderate" 201 and 500 metres, and "shallow" 501 and 1,000 metres.
Dense to moderate fog is predicted in Delhi for the next four days, it said.
The national capital recorded a minimum temperature of six degrees Celsius, a notch below normal. The maximum temperature is likely to settle at around 17 degrees Celsius.
On Thursday morning, dense fog had lowered visibility to 100 metres at the Safdarjung Observatory, considered the official marker for the city, and 50-100 metres at the Palam Observatory, the weather office said.
The city's air quality had deteriorated further due to high humidity and the air quality index read 352 at 9 am, worsening from 321 at 4 pm on Thursday.
High moisture content in the air makes pollutants heavier, making dispersion difficult. An 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'.