New York (CNN)  In-N-Out employees in five US states will no longer be allowed to wear masks as part of new company guidelines that emphasize the importance of customer service, notably showing their smiles, according to a new policy issued by the fast food chain.

Beginning August 14, employees that want to wear masks amid Covid-19 must have a valid medical note exempting him or her from this requirement, an email to workers said. The policy is in effect for workers at its restaurants in Arizona, Colorado, Nevada, Texas and Utah, which amount to about 100 locations.

A policy for its California and Oregon restaurants, where it cant ban employees from wearing masks, said that they have to wear a company-provided N95 mask. A majority of In-N-Out locations are in California, totaling about 300 out of 391.

We are introducing new mask guidelines that emphasizes 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 memo said. Employees that have to wear masks, like in the patty room or lab technicians, are exempted.

In-N-Out told employees that the medical note should clearly state the reason for the exemption and included the estimated duration. If approved, they have to wear a company-provided N95 mask.

Our goal is to continue to provide safe and customer-centric store and support environments that balance two things that In-N-Out is known for exceptional customer service and unmatched standards for health, safety and quality, the memo said.

In-N-Out didnt immediately respond to CNNs request for comment. However, the memo said that its new policies are in compliance with evolving health guidelines. The Occupational Safety and Health Administration recommends employees wear masks, however.

The changes come a few months after President Joe Biden ended the Covid national emergency, which had enabled the government to provide many Americans with tests, treatments and vaccines at no charge. Although statewide mask mandates have disappeared, health experts recommend that vulnerable individuals might still want to wear masks in crowded indoor spaces, such as restaurants.

Its not the first time In-N-Out has gone against Covid rules. In 2021, its locations in Contra Costa county (near San Francisco) temporarily closed because it didnt want to verify customers vaccination status, which was required during that time for indoor dining.

We refuse to become the vaccination police for any government. It is unreasonable, invasive, and unsafe to force our restaurant associates to segregate customers into those who may be served and those who may not, In-N-Out said in a statement at the time.

By Jordan Valinsky, CNN Business