American carrier United Airlines on Friday said it was suspending flights from Newark in New Jersey to Delhi because of the bad air quality in the Capital.

“We are monitoring advisories as the region remains under a public health emergency,” a representative for the airline told CNN Money. “We are coordinating with the respective government agencies.”

Customers with tickets booked between November 9 and November 13 will be able to re-book on flights leaving on or before November 18 at no additional cost, the airline said.

On its website, United Airlines said, “When severe weather or other major events may impact our operations, we sometimes issue travel waivers to allow you to change to alternate flights without paying a change fee.”

Delhi and several North Indian states have been in the grip of a deadly smog since Tuesday, with air quality remaining in the “severe” category through the week. The Indian Meteorological Department said the air quality may improve from Saturday as winds were picking up speed.

The Air Quality Index reading in several areas in Delhi was marginally better on Saturday, but remained above 500 in some areas. West Delhi’s Punjabi Bagh, at 615, and East Delhi’s Anand Vihar, at 529, had the worst readings at 4 pm on Saturday. An Air Quality Index reading up to 50 is considered “good” and up to 100 is considered “satisfactory”. A reading between 401-500 is ranked “severe” on the index, which means the air is dangerously filled with pollutants.