Mutton chops, chin curtains and the ever-popular beard have to be shaved off the fighters against coronavirus in the United Kingdom, the Press Association reported.

Leaders of the University Hospital Southampton National Health Service Foundation Trust sent an organization-wide email about shaving beards so masks can properly fit on their faces, according to the PA.

Derek Sandeman, medical director of the trust, passed along the U.S. Centers for Disease Control and Prevention guidelines for what styles of facial hair are acceptable.

Staff sporting the daring Dali look or choosing to look more rugged with long stubble have been requested to opt for more acceptable styles, such as a soul patch or “walrus,” as noted by the guide.

Employees who have facial hair as part of their culture or religious beliefs are exempt from the new rule.

“I recognise for some this is a big ask, that beards are so popular at present,” Sandeman said in his email, according to the PA. “However I do believe this is the right thing to do.”

The CDC image that shows facial hair styles that don’t compromise the effectiveness of face masks was posted more than two years ago on the health agency’s website.

Though it may appear that the CDC dislikes modern or more stylish forms of facial hair, the allowable grooming styles are the result of public health needs.

People who wear respirator seals for work need to ensure that their masks are sealed properly, and facial hair can get in the way of doing that.

Facial hair, which can be a food trapper depending on length and style, is not great at catching gases, vapors or air particles, the CDC wrote. Toxins can bypass facial hair and enter a person’s respiratory system.

“While human hair appears to be very thin to the naked eye, hair is much larger in size than the particles inhaled,” according to the CDC. “Facial hair is just not dense enough and the individual hairs are too large to capture particles like an air filter does.”

Getting a grip on a razor is also important to keep stubble at bay, as even day-two fuzz can decrease the amount of protection one receives from a mask, the agency warned.

Hospitals in the United States could be facing a possible mask shortage partly because of federal rules that require them to be tossed out after each use, The Washington Post reported.