In a corporate memo leaked on July 14, company bosses ordered employees not to mask, threatening to fire anyone who disobeys. The ban, which will go into effect on Aug. 14, applies to In-N-Out restaurants in five out of the seven U.S states where the chain operates: Arizona, Colorado, Nevada, Texas and Utah.

Many leading doctors and epidemiologists denounced In-N-Out’s policy as a threat to the health of both employees and customers. In a tweet, Dr. Judy Stone, an expert in infectious diseases, wrote that the In-N-Out masking ban “threatens their employees’ health.” Many doctors and labor and disability justice activists have called for a boycott of the chain.

Activists from the California-based health care coalition, Action for Care and Equity (ACE), gathered outside In-N-Out’s headquarters in Irvine on July 20 to protest the ban. ACE organized further protests last week.