The Centers for Disease Control and Prevention (CDC) has said that regular surgical masks are “an acceptable alternative” to N95 respirators, which experts insist offer far superior protection. But specialists in the field of occupational safety say that regular masks are not adequate to protect against COVID-19, and probably have caused thousands of illnesses among healthcare workers.

“There’s no doubt in my mind that’s one of the reasons that so many healthcare workers are getting sick and many are dying,” said Jonathan Rosen, a health and safety expert who advises unions, states and the federal government. As of April 23, according to The Guardian, more than 21,800 healthcare workers had contracted the coronavirus and 71 have died.

Surgical masks, designed to protect patients from a surgeon’s respiratory droplets, are not effective in blocking particles smaller than 100 microns. South Korean researchers say that COVID-19 particles are less than 0.1 microns and can pass thought a surgical mask with ease. According to The Guardian, N95 respirators will block 95 percent of tiny air particles down to 0.3 microns.

And even if health care workers supply their own equipment, their efforts may be thwarted. An article published in ProPublica reveals that a Florida emergency room nurse brought her own N95 mask to work. The hospital policies, however, did not allow staff to wear N95 masks when treating patients who were not diagnosed with the coronavirus. The nurse was taken to task and she left on unpaid leave. This scenario has been echoed in other states as well, according to The Guardian.

National Nurses United is pushing to have more N95 masks available and is also asking Congress to mandate employers provide healthcare workers with protective equipment when they interact with COVID-19 patients.

“Nurses are not afraid to care for out patients if we have the right protections,” said Bonnie Castillo, the executive director of National Nurses United, “but we’re not martyrs sacrificing our lives because our government and our employers didn’t do their job.”