NEW DELHI, Dec 26 Reuters Flight and rail services in India39;s capital city of New Delhi were disrupted on Tuesday morning as a thick layer of fog enveloped the region, reducing visibility to barely 50 metres 164 feet in some areas.

Very dense fog was observed in the city, where the temperature was just 9 degrees Celsius 48 degrees Fahrenheit, India39;s weather department said, adding dense to very dense fog was likely in the early hours of the day in some areas until Wednesday.

Dense fog contains particulate matter and other pollutants, according to the weather department, which warned of the impact this may have on the health of the city39;s 20 million residents.

New Delhi39;s air quality index stood at 376 on Tuesday morning, rated as very poor, according to the Central Pollution Control Board39;s website. Levels of 0 to 50 are considered to be good.

At least 30 flights that were to land at or depart from the Delhi airport, including on international routes, experienced delays because of the dense fog, according to Indian news agency ANI, in which Reuters has a minority stake.

About 14 trains travelling along routes in North India were similarly affected, ANI reported.

While landings and takeoffs continue at Delhi Airport, flights that are not CAT III compliant may get affected, the Indira Gandhi International airport said on social media platform X, formerly known as Twitter.

CAT III is a navigation system that enables aircraft to land even when the…