Xenon and Argon gas have been added to a list of banned substances by the World Anti-Doping Agency (WADA), after a study found they artificially boosted performances.
The announcement, made at the conclusion of a WADA Executive Committee and Foundation Board meeting in Montreal, is the result of an investigation launched after claims Russian athletes had used the substances at Olympic Games from Athens 2004 to Sochi 2014.
The investigation found inhaling the gas encourages the production in the body of the hormone erythropoietin (EPO), which enhances formation of red blood cells to improve performance, so is particularly useful in endurance disciplines.
The WADA Executive Committee unanimously approved the ban, which will go into effect after a 90-day delay for national anti-doping organisations to implement the change.
As well as being banned, the substances will be added to the list of prohibited substances, meaning that athletes will not be allowed the substances in their possession.
Despite the lack of tests for xenon in an athlete's system at the moment, unexplained increases in testosterone levels or discrepancies in a biological passport, suggesting usage of the product, will be punished.
"The message to any athlete is loaded and clear, it's going onto the ban list," said WADA President Sir Craig Reedie following the meeting.
An investigation into the effects of xenon gas was opened by German broadcaster WDR in February, after which former WADA President Dick Pound, who is still part of the organisation's Foundation Board and a member of the International Olympic Committee, condemned the use of xenon saying the he was "in no doubt that it is doping".
Despite this, in March WADA director general David Howman told insidethegames the use of xenon had been known for "years and years, before Athens 2004", but had not been previously looked at because "it wasn't an issue that needed to be addressed".
Although there is no chance of any of their medals being removed, the decision does leave somewhat of an asterisk hanging over Russian performances at Sochi 2014, where the host nation finished top of the medals table with 13 gold medals in a 31-medal haul.
Among the sports they won gold medals in were the endurance disciplines of biathlon and cross-country skiing, where Alexander Legkov led home a Russian clean sweep in the men's 50 kilometre freestyle event.
It is thought Russian athletes have used the products as far back as Athens 2004, and the Research Institute of the Russian Defence Ministry reportedly set out guidelines in 2010 for the administration of xenon gas to athletes.
But the Russian medical-xenon producer, Atom Medical Centre, which received national honours for its efforts preparing athletes for the Athens 2004 and Turin 2006 Olympics, disputes the effect of the gas on the release of EPO in humans and the claim that inhaling it constitutes doping.
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May 2014: WADA puts xenon gas on draft prohibitive list and could ban it by end of year
March 2014: WADA could ban performing enhancing gas after claims Russians used it at Sochi 2014
February 2014: WADA set to investigate claims Russians used performance enhancing gas at Sochi 2014