Heavy smog coupled with dense fog affected operations at the Guru Ram Das Jee International Airport in Amritsar on Wednesday. The airport authorities are waiting till visibility gets better to resume full services, reported India Today.

According to officials, the smog increased after Diwali celebrations. On Monday, a day after the festival, the PM 10 levels (particulate matter that is under 10 micrometres in diameter) went up to 321.55 microgram per cubic metre, much higher than the safe limit of 100 microgram. Levels of PM 2.5 (particulate matter that is under 2.5 micrometres in diameter) also reached 95.10 micrograms, which is several times higher than the safe limit of 60 micrograms per cubic metre.

However, according to Skymet Weather, the dense fog is a mark of the onset of the winter season. It led to zero visibility from 6 am to 9 am on Wednesday. “Operations have been suspended for some time due to the fog,” an airport official told Skymet Weather.

The airline whose flights were delayed includes Air India, Air Canada, Spicejet and Qatar Airways. According to weather experts, the fog will remain for the next two or three days with high humidity and low wind activity.