After 21 years in military medicine, there isn’t much that rattles Richard Barnett. He was part of the Marine force that invaded Baghdad in 2003, where he intermittently came under enemy fire.

But during a 12-hour overnight nursing shift at West Hills Hospital and Medical Center in Los Angeles, the working conditions became more than he could accept. Ill-fitting masks. Poor sterilization technique. Worst of all, two patients with covid-19 slipped through the screening procedures, exposing health-care workers who treated them without knowing they were infected, he said.

At the end of the shift, at 7 a.m. March 15, Barnett quit and turned in his badge.

“It was a real obvious choice,” he said. “I either leave before I get sick and possibly get my family sick. Or I leave after I get sick. It was a simple risk versus benefit challenge.”

Like Barnett, some health-care workers have begun to resist pressure to work with inadequate protection during the coming tsunami of coronavirus cases. To do so, they must buck the pandemic’s all-hands-on-deck ethos, the medical tradition of accepting elevated risk in a crisis and the threat of discipline from employers.

Confrontations and difficult personal decisions are occurring as hospital administrators enforce rationing of masks, face shields and other equipment for workers worried about protecting themselves.

“It’s killing me. Every day I am having to discuss with my wife that I literally feel like a coward for running away from this,” Barnett said. “I either suck up that particular feeling and put it in my pocket or I put my family at risk.”

In a statement, West Hills said it “has been working diligently to help ensure we’re prepared for potential issues related to the spread of coronavirus. Our preparedness efforts include reinforcing appropriate infection prevention protocols, helping to ensure we have needed supplies and equipment, staffing contingency plans and emergency planning and preparedness.”

The widespread shortage of masks, eye shields and other protective equipment for health-care workers at U.S. medical facilities has become a fact of the pandemic. Nurses and others have complained for weeks, publicly and privately, about the risk of leaving themselves needlessly exposed to a highly contagious respiratory disease. Even with the best of equipment, health-care workers suffer disproportionate losses in outbreaks like this.

Medical facilities normally operate on a just-in-time approach to receiving supplies, secure that the supply chain can meet their everyday needs, with little incentive to stockpile large amounts of equipment.

With the government’s failure to stockpile enough supplies for the pandemic, equipment is now so limited in some places, including New York and Washington state, that volunteers are sewing masks in their homes and workers are trying to make one-time-use equipment last for days.

The Centers for Disease Control and Prevention first called for workers to wear N95 masks, which fit tightly over the nose and mouth and filter out 95 percent of most airborne particles. Later, the agency relaxed that guidance and said looser, less effective surgical masks were acceptable.

Labor unions have noted that in China, where supplies were more plentiful, health-care workers were told to double up on gowns and other protective equipment. They have warned of a catastrophe if many health-care workers fall ill.

Dee Shine was sitting at her desk at MedStar Washington Hospital Center’s eye clinic last week when she took a surgical mask from a box behind her and began to greet patients. She said some doctors had been pleading with their bosses to close the office, but she accepted being there. She needs the $21.36 an hour she is paid.

Soon, she said, she was summoned to the human resources department and told to go home. She had been suspended indefinitely for wearing the mask.

“They said they were saving them for staff,” she said, “and the masks would scare the patients off.”

Shine, a 40-year-old mother of four, said she has been a medical office assistant at Washington Hospital since 2015. A day earlier, she said, her manager had asked her to take off the mask. When she explained she had asthma and no one had asked her to remove the mask, she believed continued use of it was allowed.

“I told them I already have asthma and that my kids were out of school because of everything going on. I told them I felt safer with the mask,” she said. Shine said she will file a complaint with the Equal Employment Opportunity Commission and her labor union.

MedStar spokeswoman So Young Pak said the medical center is “unable to discuss this associate’s personnel matters. However, the health and safety of our associates is always our top priority. If any associate has health issues, they are advised to report to our occupational health clinic to determine necessary actions. This process is set in place to ensure the safety and security of both associates and patients.”

A MedStar nurse, who said she is working without N95 masks, shoe covers and occasionally without eye shields, said her unit is employing a different kind of pressure. At morning huddles, the nurse, who spoke on the condition of anonymity because she fears she will lose her job, said supervisors have singled out nurses who are insisting on a higher level of protection, telling others “they’re not following our guidelines and they’re using up resources.

“I’m just terrified,” she said.

The hospital spokeswoman said the medical center has “an adequate supply of personal protective equipment for all of our clinicians and team members and we project we will keep up with demand. All our associates, including our nurses, have the appropriate PPE needed to take care of covid-19 or any other patient needing isolation. Our use of PPE can change almost daily, based on CDC guidance and new evidence from other countries and specialty societies.”

Heather Riebel, a pediatric cardiologist in San Antonio, said these interactions reveal the disconnect between hospital administrators and doctors and nurses on the front lines.

“I’d like to see all hospital administrators, CEOs, CFOs climb down from their ivory towers and be told to walk through their hospitals, emergency rooms and everywhere. Let’s see what type of personal protective equipment they would want,” she said.

Barnett, 57, a telemetry nurse from Thousand Oaks, Calif., said the financial toll of quitting will not be severe. He has military retirement benefits. He had worked at West Hills for seven years, five of them full-time, before gradually scaling back to one shift a week and occasionally more as a per diem employee.

He is married with two grown stepchildren, one of whom has type 1 diabetes. Though that stepdaughter no longer lives at home, Barnett said he worries most about infecting her, because the condition makes her more vulnerable to severe illness if she contracts covid-19.

He said he has many colleagues who can’t afford to quit, including some who are working with underlying conditions that make them vulnerable to severe consequences from the virus. One is living in a trailer to avoid bringing the virus home to a vulnerable child.

What he’s going to miss is the camaraderie and sense of mission the nurses on his floor shared. He blames management at the for-profit hospital for the failure to adequately enforce screening of patients and stocking supplies.

“If the hospital was handling this correctly, the nurses and doctors would be safer at work dealing with the virus . . . than I would be walking on the street,” he said.

In its statement, West Hill said “like all hospitals, we treat patients with infectious diseases every day. West Hills Hospital remains a safe place to work and receive care. We continue to work in partnership with our county health department and the CDC.”

Now, Barnett worries for his former colleagues but is sure he made the correct decision for himself.

“It’s a lot easier to deal with being shot at,” he said. “I know where it’s coming from and when they stop shooting, I’m no longer in danger. When you’re dealing with infectious disease, you have no way of knowing where it’s coming from.”

Lena H. Sun contributed to this report.