A tragic cryotherapy session in Paris resulted in the death of one woman and the critical hospitalization of another due to a nitrogen leak from a cold chamber, according to French investigators.

The incident occurred on Monday evening at a small sports center in the 11th district of the French capital, a police source reported.

Preliminary findings suggest that a nitrogen leak from the cryochamber caused the poisoning, according to a source close to the investigation. An employee of the gym, in her late 20s, died as a result.

A client of the establishment, in her 30s, was hospitalized and remains in critical condition.

The Paris public prosecutor’s office has launched an investigation into the cause of death.

Three individuals who came into contact with the victims and provided initial first aid also received treatment, the police source added.

The gym, which had 150 people present at the time of the incident, was promptly evacuated.

A body covered with a white sheet was seen being removed from the sports center.

Screens were erected to shield the scene in front of the gym’s entrance and along the pavement.

Nitrogen, a colorless and odorless gas, is commonly used in cryotherapy.

During a typical session in a walk-in chamber, individuals are exposed to temperatures below -100°Celsius for a maximum of three minutes.

Proponents of whole-body cryotherapy claim it effectively reduces muscle soreness, stress, rheumatism, and various skin conditions.

Many star athletes and celebrities have embraced whole-body cryotherapy as an alternative to ice packs and cold water baths.

However, numerous experts caution that the treatment lacks sufficient medical validation and advocate for further research to ascertain its short- and long-term effects.

Diego Brisset, 26, mentioned he had planned to work out at the gym but was informed of its closure on Monday evening.

He also noted that he does not engage in cryotherapy.

“I was always told it was dangerous,” he stated.

Cryotherapy faced increased scrutiny in the United States in 2015 after a woman froze to death at a spa in Las Vegas.

The 24-year-old woman was believed to have entered one of the spa’s cold chambers after business hours to alleviate some aches and was discovered the following day by a co-worker.