ATLANTA >> Trapped in a walk-in hotel freezer with subzero temperatures, Carolyn Robinson Mangham knocked so desperately on the door that the skin on her knuckles had worn away, her husband said in a lawsuit.

When the door finally opened 13 hours later, the coroner said, the 61-year-old kitchen worker was lying on the metal floor, wearing her black shoes and pants, a white cook’s shirt and a black apron. Her head and eyes were frozen solid.

Mangham, who died in March in Atlanta, was among a handful of workers who, in the last 15 years, were found dead in freezers, federal records show. Some were trapped by broken doors and either froze to death or were overcome by lethal fumes.

Experts say the deaths are preventable, but it’s not likely the federal government will draw up any specific regulations dealing with freezers. One reason: They’re more inclined to enforce broad rules for employers, such as making clear exits available.

“This should never happen. It’s tragic, and the families are left with devastation,” said Kim Bartels, whose brother Jay Luther died in a walk-in freezer in 2012.

Luther, a 47-year-old chef and co-owner of a cafe in Nashville, Tennessee, went into his restaurant’s freezer and the door shut behind him. For reasons not explained, there was no release mechanism to open the door, the U.S. Occupational Safety and Health Administration concluded in its report. Luther suffocated from breathing carbon dioxide vapors that came off dry ice inside the freezer, a medical examiner found.

“There’s no question that technologies exist — old and new — that could address this issue,” said David Ringholz, chairman of the industrial design department at Iowa State University.

Motion sensors, for instance, could disable doors anytime movement is detected inside a large walk-in freezer, he said. Other experts suggested alarms, a cellphone or even an axe kept inside to help someone get out.

Some safety upgrades would cost hundreds or thousands of dollars, and that expense can be a big obstacle to improvements.

Adam Finkel, a former OSHA regional administrator for the Rocky Mountain states, recalled when a 55-year-old woman died inside a freezer at a lodge in Colorado in 2002.

“That one really struck me as a terrible way to go,” said Finkel, now executive director of the Penn Program on Regulation at the University of Pennsylvania.

There had been problems with the freezer door at the Westin Peachtree Plaza hotel in Atlanta, according to the lawsuit, which seeks unspecified damages. Several months before her death, an exit mechanism failed inside the 12-by-10 freezer, and a hotel employee “had to beat on a back wall in order for someone to let her out,” the medical examiner’s report states.

When Mangham died, the medical examiner, OSHA and a representative of an equipment servicing company performed more than 30 tests on the door’s exit device, and it opened properly each time, hotel spokeswoman Sally McDonald said.

However, three weeks later, the exit button malfunctioned during a follow-up inspection, this time trapping two people, who had to beat on the door to alert others outside to free them, the autopsy report states.

OSHA found that the hotel exposed workers to hazards, and levied a fine of more than $12,000 in Mangham’s death. The hotel agreed to frequent and regular inspections of its freezers, including the door-release mechanisms, the agency said.

After Mangham’s death, her co-workers and their union, UNITE HERE, demanded that emergency buttons be placed inside the freezers so that if someone becomes trapped, that person can alert building security or the fire department. So far, the hotel hasn’t said whether they plan to have the buttons.

Such devices would be similar to those already in most elevators, said Lee Gray, an architectural historian at the University of North Carolina-Charlotte who wrote a book about the passenger elevator.

Westin Peachtree Plaza workers are also pushing for a better way of tracking employees, so that if someone disappears as Mangham did, others will know to look for them. The hotel has agreed to develop a procedure for workers to check in and out with others when they enter remote areas, OSHA said.

The hotel and its parent company, Starwood Hotels and Resorts Worldwide, have not said whether they are considering changes at any other hotels in the company. Starwood was acquired this year by Marriott International for $13 billion, creating the world’s largest hotel company.

In the wake of Mangham’s death, the government could draft new rules and regulations or issue a bulletin or safety alert about the dangers of becoming trapped in freezers, which could raise awareness, said Celeste Monforton, a former OSHA official now with Texas State University.

But creating new, overly specific regulation is sometimes not helpful, said Wayne Li, director of the Innovation and Design Collaborative at the Georgia Institute of Technology. If regulations are too specific, they don’t account for new technological advances and can become outdated and stifle innovative approaches, Li said.

Aaron Rabinowitz found his father dead inside the freezer of his family’s San Diego cafe nine years ago. He said he thinks that some type of alarm would be a good idea, though it may not have helped his father because he was quickly overcome by the dry ice fumes.

“I’m in there myself daily,” said Rabinowitz, who now runs the cafe. “There are safety latches. They can freeze up where you have to give it a really good kick. Somebody who is not strong enough might have trouble with it, so I think that (the alarms) would be a nice extra level of safety beyond a safety latch.”