In-N-Out employees who wear a mask to work without providing a doctor’s note that discloses a reason for doing so may face disciplinary action effective Aug. 14, the fast food chain said in a letter to workers.

The policy applies to all store and support associates working in Arizona, Colorado, Nevada, Texas and Utah, except for those who are required to wear masks or other protective equipment as part of their job duties.

“We are introducing new mask guidelines that emphasize the importance of customer service and the ability to show our Associates’ smiles and other facial features while considering the health and well-being of all individuals,” the company wrote. “We believe this policy will also help to promote clear and effective communication both with our Customers and among our Associates.”

Employees must present a medical note to a manager or HR representative to mask at work under the new policy. Those who do continue to wear masks must wear a company-provided N95 mask, but different types of masks may be worn if this is specified in an employee’s medical note.

Failure to adhere to the policy may result in disciplinary action “up to and including termination,” In-N-Out said, “based on the severity and frequency of the violation.”

The company noted that its policy is subject to local health authority guidelines and regulations, and that such guidelines would “take precedence” in the event that the mask policy conflicts with them.

“At In-N-Out Burger, we’ve communicated with our smiles since 1948, and a smiling Associate helps to set a warm and inviting atmosphere in our stores,” Denny Warnick, In-N-Out's chief operating officer, said in an email to HR Dive. “We believe that wearing a mask literally adds a barrier to communication - much of which is nonverbal - and promotes a more distant and disconnected environment.”

The policy does not cover locations in California, where the privately held company is headquartered, or in Oregon, where it has five locations. Both states prohibit employer policies that prevent employees from wearing face coverings.

Mask requirements have generally faded in the U.S., with hospitals and healthcare providers among the list of organizations to roll back mandates for patients, visitors and employees, The Wall Street Journal reported. Fewer Americans are worried about catching COVID-19 than in years past, according to a February Gallup survey that also showed about three in 10 respondents continued to wear masks outside of the home.

May 2023 guidance from the Centers for Disease Control and Prevention stated that while people may choose to wear a face covering at any time, local COVID-19 hospital admission levels are a tool that can help people determine what prevention steps they should take, including wearing masks or respirators. The CDC included separate considerations for people who are at increased risk of severe illness, including older people, pregnant and recently pregnant people and people with certain medical conditions.