An-inert gas used to anesthetize hospital patients, as a satellite propellant and inside movie projector bulbs has been officially banned by for use by endurance athletes looking to boost their oxygen-carrying red blood cells.

Xenon and its Nobel gas companion, argon, are now on the World Anti-Doping Authority’s list of banned substances list for athletes competing in all Olympic events beginning Sept. 1. WADA took the action after Russian skiers and biathletes admitted to using xenon at the Sochi Winter Olympics in February. The team’s coach told German reporters that they used the gas because it wasn’t illegal and mimicked the effects of training at altitude.

While there has been little published research on the benefits of xenon, a Russian medical supply company was assisting the athletes to perform better.

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“It had the potential to enhance performance,” said Matthew Fedoruk, science director at the U.S. Anti-Doping Authority in Colorado Springs. “There have only been couple of animal studies that indicated that xenon is similar to going to altitude and stimulating the protein (erythropoietin) EPO. This was a way to stimulate red cell production.”

EPO is the term to describe both the protein that stimulates the body’s natural production of red blood cells, as well as the pharmaceutical drug that does the same thing. EPO is also taken by millions of anemia patients to blood their blood supply.

Although argon makes up less than 1 percent of the Earth’s atmosphere, (xenon has almost disappeared from our air), Fedoruk said the Russian athletes were breathing a mixture of 50 percent oxygen and 50 percent xenon.

Given its anesthetic properties, any slip-up in the amount of xenon could have killed the athletes, according to Fedoruk. “It’s like sleeping gas,” he said. “It could put you out forever.”

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The long-term affects of using these gases has not been studied, he added. It works in the body by activating a protein called Hif (hypoxia inducible factor)-a that causes an increase in red blood cells. WADA Director David Howman said the specter of xenon-huffing skiers (and possibly cyclists and runners) arose after news reports from the Sochi games.

“Our scientists looked at it pretty closely immediately and decided it should go on the (banned) list immediately,” Howman said from Montreal. “Rather than wait until the end of the year, we got a process that says if it is important, it should be done immediately.”

WADA announced a possible ban of xenon in May. The decision was finalized last week.

Although xenon and argon disappear quickly from the bloodsteam, and make detection difficult, Howman said WADA, however, can still detect the effects of the gas through other means.

While Olympic athletes won’t be able to use these exotic gases before, a similar ban does not extend to pro football, baseball, basketball or hockey players in the United States.