Disturbing Cryotherapy Incident Leaves Woman Dead and Another Injured

A malfunctioning cryotherapy machine seems to have led to the tragic death of a 29-year-old woman in Paris, France, this week.

The unusual death occurred Monday evening at the On Air gym in east-central Paris, according to local law enforcement. The woman, a gym employee, appears to have died due to a nitrogen leak from the cryotherapy machine. A second woman, age 34, was critically injured and is currently in intensive care.

Cryotherapy, or cryostimulation, is an emerging practice. One trendy form of it, whole-body cryotherapy, requires people to be completely exposed to extremely cold temperatures for several minutes at a time. Some research has suggested cryotherapy can possibly relieve certain kinds of pain and inflammation, and it might have other health benefits, such as improving sleep.

Cryotherapy machines often use chilled liquid nitrogen to produce these temperatures. In this case, temperatures reached as low as -148 degrees Fahrenheit (-100 degrees Celsius), according to Medical Express. But when it’s a gas, nitrogen is both odorless and colorless. As a result, the European Industrial Gases Association (EIGA) has warned that improperly designed or maintained machines can be a safety hazard. If too much nitrogen gas seeps out into the cryo-cabin or surrounding space, it can quickly displace oxygen without notice, which can then asphyxiate people.

That seems to be the case here. Both women were in cardiac arrest by the time emergency services arrived. Three other people who attempted to revive the women were also taken to the hospital, while around 150 people were evacuated from the building.

According to police, the machine was supposedly repaired earlier in the day—a repair that might have gone tragically wrong. But authorities say that they are still conducting an investigation into the matter. “An autopsy and toxicology analysis will be carried out to determine the precise cause of death,” a spokesperson for the Paris prosecutor’s office told The Guardian.

Cryotherapy-related deaths are rare, but not unheard of. In 2015, for instance, a spa employee in Las Vegas died accidentally of suffocation from using a cryotherapy machine.