Flight attendants enforcing mask mandates onboard are worried about physical attacks from travelers, Sara Nelson, international president of the Association of Flight Attendants, told CNBC’s “Squawk Box” on Monday.

The Transportation Security Administration announced Thursday it would double fines for passengers who refuse to comply with the federal mask mandate for air travel. The union president said the TSA’s updated policy could help address more mask-related conflicts in the airport, thereby reducing issues for flight attendants to handle on the plane.

“We’re concerned every single day when we go to work and put that uniform on, are we the target and going to be punched in the face today,” Nelson said.

Flight attendants have long been tasked with policing safety rules and regulations in flight, Nelson said, but they’ve experienced an uptick in conflicts stemming from mask mandates. The Federal Aviation Administration said July 7 that mask requirements comprised 75% of its unruly passenger complaints since the start of 2021.