Deadly Air Kills Experienced Diver

Andrew Thwaites, 44, a very experienced diver and Queensland, Australia, Fisheries Director died from carbon dioxide and carbon monoxide (CO) poisoning after his air tank was filled with grossly high levels of these toxic gases. The Brisbane Coroner's Court heard that the remaining air in his tank contained 2366ppm of CO as well as high levels of CO2. The recreational limit is 5ppm.

In fact, Thwaits, himself had filled his and six other tanks on 13th July 2016, and of those that were recovered and tested, two had high levels of CO. Apparently, other tanks also had been filled from the same compressor at the clubhouse of the Underwater Research Group of Queensland. Thwaites, a widely respected marine scientist, was one of a small number of members approved to use the club's compressor.

The Court also heard that Thwaites' partner, Dr. Kelly-Anne Masterman, suffered nausea, splitting headaches and short-term memory loss after the dive. The air in her tank was found to contain CO at 820ppm, as well as CO2.

Both CO and CO2 are odorless gases, and neither is detectable without chemical gas analysis, but such contamination is usually caused by a compressor air intake that is contaminated by the exhaust gases from the compressor's prime mover, a diesel or gasoline engine.

Gas expert Bill Hunt testified that the compressor had not been properly maintained, the compressor room had inadequate ventilation, and the filtration was completely inoperational. The air produced had not been tested since 2011. Because the compressor had irrevocably broken down since the incident, it was impossible to determine why such high levels of CO were present in Thwaites' tank.