The air quality in Delhi and its neighbouring areas was in the “severe” category on Friday. Visibility in the Capital was also low due to a dense layer of fog.

Delhi’s average air quality index at 1 pm was 462, according to the Central Pollution Control Board. At 4 pm on Thursday, the Capital’s AQI was 429. This value was an average of 24 hours. According to the agency’s air quality index or AQI, any reading above 100 on a scale of 500 is progressively unsafe for health.

The minimum temperature in Delhi on Friday – 6.7 degrees Celsius – was higher than normal due to cloudy weather, PTI reported, citing the Indian Meteorological Department.

Meanwhile, AQI value at 1 pm at Noida’s Sector 62 was 470 and 486 in Ghaziabad’s Indirapuram area. Gurugram’s Vikas Sadan registered an air quality index value of 420.

Parts of Rajasthan, Punjab, Haryana and Bihar also saw heavy fog on Friday morning, ANI reported. As many as 14 trains were running late because of the weather.

Kuldeep Srivastava, the head of the Regional Weather Forecasting Centre in Delhi, said the reduction of wind speed across North West India has contributed to the poor air quality, Hindustan Times reported. “In Delhi, it [wind speed] is only around 6 mph and the wind direction is south-westerly,” he added. “So, the air quality has deteriorated and there is little possibility of pollutants dispersing.”

Minimum temperatures in North West India are likely to remain below normal over the next few days, the newspaper reported, citing the weather office. Punjab and Haryana, Delhi, Uttar Pradesh, and Bihar are likely to experience severe cold in the next few days.