With new federal rules in place, Delta Air Lines said it will no longer allow emotional support animals on its flights.

Airlines and passengers had raised concerns about safety and other issues as more and more travelers brought animals on board. By certifying their pets as emotional support animals, pet owners had been able to avoid paying extra fees when flying. Under the new U.S. Department of Transportation rules taking effect next week, airlines are no longer required to grant special access to emotional support animals.

Delta’s policy change means it stopped accepting new bookings for emotional support animals beginning last week. Those who already have tickets confirmed with the animals can still fly as planned. American and Alaska Airlines recently have announced similar policies.

In compliance with federal rules, Atlanta-based Delta said it also will lift its ban on pit bulls as service animals. Service animals are different from emotional support animals in that they are trained to perform tasks to help their owners with their disability. Delta said it will also require documentation for trained service dogs.

However, the airline said it will continue to deny boarding to any trained service animal “that poses a threat or demonstrates aggressive or inappropriate behavior in a public setting.”

The DOT and Delta had been at odds on the pit bull ban, which Delta said was a response to safety concerns. The agency said bans of service animals solely based on breed are not allowed.

“The DOT’s final rule enables airlines to put the safety of all employees and customers first, while protecting the rights of customers who need to travel with trained service animals,” said Delta senior vice president of in-flight service Allison Ausband.

Delta said it has seen an 85% increase in animal incidents including urination, defecation and biting since 2016. The airline was sued in 2019 by a customer who was mauled by another passenger’s emotional support dog on a flight.

The airline said passengers can still travel with a pet in the cabin for $125 each way on domestic flights, if the pet meets requirements.

“We strongly believe this policy change will enhance the overall travel experience for everyone,” said Delta senior vice president of corporate safety and security David Garrison in a written statement.