A 19-year-old restaurant worker at McDonald's was physically attacked by a customer after she asked him to wear a mask. She is not alone. Experts say many restaurant workers have been harassed by anti-mask customers since the pandemic began and local officials as well as restaurant owners have mandated the wearing of face masks in certain situations. 

According to Business Insider, Maria Resendiz, from Oakland, California, was working at drive-thru when she asked the customer who was pulling up to don a mask as required by her manager and local government. He became belligerent, spewing racial slurs, and reached through the window to grab and slap her. She was taken to the hospital.

McDonald's issued a statement Wednesday reiterating its position on personal safety and asking restaurants to require "proper mask use by crew and – where applicable-customers."

Experts tell Business Insider the new responsibility to enforce mask mandates can put both employees and customers in danger. Several people have been shot in recent weeks over arguments about wearing masks in restaurants. According to WBTV, a man was shot in a Chili's parking lot in North Carolina after an argument about face mask compliance.

Business Insider's Aria Bendix said people who use masks as a political issue or culture war are ignoring the evidence they are highly effective in preventing the spread of the coronavirus. According to The News Tribune, a University of Washington study predicted if 95% of the U.S. population wore face masks in public, the country could prevent about 33,000 COVID-19 deaths.