A new cryotherapy center — the second in Honolulu — is opening amid lingering safety questions tied to the death of a former Hawaii woman last year at a center in Nevada.

Customers are attracted by cryotherapy’s minutes-long deep-freeze treatments, which are touted as offering quick relief for pain and workout recovery, promoting weight loss and skin tightening, and providing anti-aging benefits.

Cryotherapy Hawaii co-owner Egan Inoue said, “We’ve been slammed” with friends and family eager to try the spa, which will open to the public in February for what he touts as “rejuvenation, recovery and renewal therapy.”

Unregulated in Hawaii and most states, full-body cryotherapy raised eyebrows after the death of Roosevelt High School graduate Chelsea Ake-Salvacion, who used a cryotherapy machine after hours Oct. 19 at a Las Vegas spa where she worked. She was found dead the next day inside a tank, where users are subjected to subzero temperatures.

Cryotherapy machines use liquid nitrogen to chill the air. Inoue said his machine, identical to the one used by Ake-Salvacion, produces a mist from the liquid nitrogen, dropping the air temperature to minus 250 degrees Fahrenheit.

The coroner ruled the woman’s death as accidental from asphyxia caused by low oxygen levels inside the cryotherapy chamber, where oxygen levels are brought down to less than 5 percent — well below the 21 percent oxygen of normal air.

In November the state of Nevada issued health guidelines for the use of a cryotherapy chamber. Nevada’s Health Department recommends that the machines not be used by anyone younger than age 18, under 5 feet tall or with health conditions such as a history of stroke, high blood pressure, seizures and infarctions. The recommendation also applies to anyone who is pregnant, fitted with a pacemaker or claustrophobic, the Associated Press reported.

The Nevada Department of Health and Human Services also suggests limiting customers to one session a day, with each session lasting no longer than three minutes. And blood pressure should be checked before and after.

In the aftermath of Ake-Salvacion’s death, the Las Vegas business was shut down because its owners were unable to provide proof of workers’ compensation insurance, and it didn’t have a license to perform skin and other advertised aesthetician services, according to news reports.

Workers say the business has since reopened, but the owners did not return a call to the Honolulu Star-Advertiser.

Shelly Kunishige, spokeswoman for the Hawaii Department of Commerce and Consumer Affairs, said the question of regulation came up after the Las Vegas death. In Hawaii the Legislature would decide whether to pursue regulatory measures, she said.

Kunishige cautioned that customers seeking a medical treatment should make sure the operator has an active medical license.

Dr. Jay Marumoto, an orthopedic surgeon who specializes in sports medicine and advanced arthroscopy and joint reconstruction, said whole-body cryotherapy is “nothing new, but it’s a new fad and it’s going through a fad phase.”

Marumoto says the Internet has spurred its recent popularity among athletes, movie stars and other celebrities. “Then everybody jumps on the bandwagon,” he said. “People have done ice baths and jumped into cold water since the 1800s.”

Marumoto said some athletes say “it cools down the whole body, reducing inflammation, and they get better quicker, but there’s no scientific proof that that really works.” Cryotherapy’s only proven medical applications have been for extreme trauma or spinal cord injuries, he added.

“Applications for sports and other purported medical benefits aren’t proven,” including weight loss, Marumoto said. “It doesn’t mean it doesn’t work, but we haven’t done a good body of medical study to see if it works.”

As for safety, Marumoto said, “People have to be healthy. They can’t have peripheral vascular disease (disease of the blood vessels to the extremities), or they could be at risk for frostbite and superficial danger to their skin.”

Smokers, diabetics and kidney disease sufferers, who tend to develop blood vessel disease more commonly, should not use it, he said. “It can be safe for certain people, but people of young or advanced age or any significant medical problems should check with their primary-care physician before undergoing extreme cryotherapy,” Marumoto said.

Inoue, who is 50 years old and a former mixed martial arts world champion, said due to cryotherapy, “I’m able to recover faster, so I can train more.” He has had two surgeries in his knees. Even so, Inoue said he’s now able to snowboard without any pain, and arthritis in his fingers has eased.

In addition, Inoue claims that due to one’s metabolism speeding up during a cryotherapy session, “you lose about 500 to 800 calories in the next 40 hours.”

Both Ryan Harwood, co-owner of Honolulu Cryotherapy, the first center in Hawaii, and Inoue have read reports related to Ake-Salvacion’s death. Harwood said it could have been prevented if the woman had not been alone. At his cryospa, which opened in October, someone is always tasked with monitoring a person in a tank, Harwood said.

Honolulu Cryotherapy charges $45 for kamaaina and $59 for visitors. Inoue has yet to set rates for a session.