A 24-year-old woman was recently found dead in one of the freezing chambers that celebrities like Demi Moore swear by

Last week, 24-year-old Chelsea Ake-Salvacion was found dead inside of a cryotherapy chamber at a clinic in Las Vegas, the New York Times reported.

The incident is raising questions about the safety of this relatively new spa experience that thousands of Americans, including world-class athlete LeBron James and actress Demi Moore, are using for its purported benefits, which include everything from enhanced athletic performance to smoother skin.

Whole body cryotherapy is a quick-and-easy spa experience that exposes the body to temperatures anywhere from minus 150 to minus 290 degrees Fahrenheit. That's incredibly cold. For comparison, the coldest temperature ever recorded on Earth was minus 135 degrees Fahrenheit in Antarctica in 2010.

The chamber that Ake-Salvacion was found in reached temperatures as low as minus 240 degrees Fahrenheit.

The procedure involves standing nearly naked in a chamber filled with super-chilled air where the idea is similar to why we sometimes place ice packs over sore muscles: The chilled air reduces inflammation across the entire body and can, therefore, relieve pain and enhance muscle recovery.

European countries including Poland, Finland, and the UK have been using cryotherapy as a health treatment since the '70s, but it was only introduced in the US in 2006.

For professional athletes like basketball star LeBron James and Texas Rangers' pitcher C.J. Wilson, the two-to-three minute procedure is more preferable than spending ten or more minutes soaking in an ice bath - though there's no evidence to suggest one is better for you than the other.

While the body can handle these extreme temperatures for a few minutes, any longer can prove dangerous. That is why you're never supposed to use the chamber alone.

Visit any of the US-based centers in New York City, Chicago, Los Angeles, and elsewhere, and you'll have an expert stand by and control the temperature of the air as well as how long you've been in the chamber. Sometimes it is easy to lose track of time as Business Insider's Graham Flanagan experienced when he visited New York City's Kryolife (that's him on the left):

Ake-Salvacion had been working on a center that offers whole body cryotherapy in Las Vegas, and reportedly was using the chamber after work hours - presumably alone.

According to the Times, a local coroner said that Ake-Salveacion's death had not yet been determined, but the girl's uncle said that the coroner told him the body was "rock-hard solid."

What exactly happened is unclear but the Las Vegas Metropolitan Police Department said that it did not appear a crime had been committed, The New York Times reported.