Rebreather Deaths Are on the Rise

DAN has also been collecting information about diving rebreather deaths since 1998. So far, 80 deaths have occurred, and DAN says the number of rebreather deaths has tripled in the past decade. The percentage of fatalities involving rebreathers among North American divers increased from one to five percent of total dive-related deaths in six years between 1998 and 2004.

Richard Vann, Neal Pollack and Petar DeNoble of DAN analyzed the 80 cases to determine the triggers for rebreather deaths. Only three cases were caused by gear malfunction. Equipment trouble and buoyancy problems were more common for rebreather divers than traditional open-circuit divers. Eleven cases involved procedural problems or inappropriate preparation by the diver, like the oxygen valve and displays not turned on, an incorrectly installed oxygen sensor and loose connections. The four rebreather deaths with buoyancy problems were apparently caused by the divers removing their mouthpieces after ascent and failing to close it, which led to their sinking.

Drownings, entrapment and entanglement are less of a problem with rebreathers, but the largest difference between rebreather and open-circuit deaths was inappropriate gas. Hypoxia and oxygen toxicity were responsible for more than half the deaths. DAN says that’s because the diluent supply in a rebreather is small and can be quickly exhausted by a leak or multiple up/down dives. There were four cases of insufficient gas; one was caused by a gas leak in the breathing loop that led to a rapid ascent and air embolism. There were five seizures probably due to oxygen toxicity. Thirteen rebreather divers lost consciousness early in their dives, suggesting hypoxia.

As in standard diving scenarios, rebreather deaths happen to the most experienced divers and in the most innocuous of places. Harvey L. Harris, an advanced rebreather diver from Wilder, Idaho, was found dead in the pool of a dive shop while wearing his rebreather. He died of accidental drowning due to asphyxia. After diving solo near Tacoma, Washington, the 51-year-old Harris had stopped by Thunder Reef Divers to get his tank filled. He still had some gases left from his shore dive so he decided to use it up with his rebreather in the shop’s pool for practice. But because his system wasn’t working properly, Harris breathed in too much carbon dioxide and too little oxygen, lost consciousness and drowned while sitting at the bottom of the 10-foot pool.