In 2005, his father, David Matthews, brought manslaughter charges against members of the expedition’s organizer and the oxygen gear supplier. (In England, a citizen can bring a private criminal prosecution.) But the next year, a judge threw out the case, ruling that there was no evidence proving that Michael Matthews, whose body was never found, had experienced equipment problems on the day he disappeared.
Still, the industry remained largely unregulated, and climbers continued to report problems.
Robin Moore, an American physician, was near the top of Everest in 2017 when she started gasping for air. Guides said her equipment looked fine and Moore had oxygen, but she soon fell unconscious. A Sherpa changed the cylinder, and oxygen began flowing again, snapping her awake, she said.
In 2012, Ted Atkins, a British engineer who founded Topout, an oxygen systems company that offered one of the first competitive alternatives to Poisk, was screwing a Russian regulator onto a new European cylinder when it exploded in his face.
After the accident, Atkins found that problems with oxygen systems were more pervasive than widely thought. Ten percent of used Poisk cylinders he had tested were leaking through their valves, he estimated, a striking number considering that most climbers use several cylinders each for a summit attempt.
Meanwhile, regulators — which help climbers gauge their oxygen supply — were sometimes freezing, dispensing no oxygen or giving inaccurate readings. More recently, Atkins found that a smaller number of cylinders were losing oxygen through the body of the tank, visible when submerged in water as gas bubbling out.
“Every time you fill a cylinder, when you put the gas pressure in it, it expands,” he said in an interview with The New York Times last year. (Atkins died in an unrelated climbing accident in August.) “That expansion causes metal fatigue.”