A red alert has been issued for dense fog in Delhi, Punjab, Haryana, and Chandigarh.

Experts have requested people not to venture out in their vehicles between 4 am and 10 am, unless it is unavoidable.

A thick blanket of fog in the national capital has led to over a hundred flights being delayed.

When fog causes visibility to drop below 50 metres, it is categorised as very dense fog. The red alert, which is the highest level of warning, is rarely used. The warning for Friday is primarily for deterring people from venturing out as the 4 am to 10 am time window could lead to car pile-ups and deaths on the road in Delhi-NCR, which have already been reported since the fog thickened in the last three days.

Tomorrow, also Delhi is expected to witness very dense fog, with the minimum temperature expected to hover around seven to eight degrees Celsius, the India Meteorological Department (IMD).