When four Oaky Creek miners suffered smoke inhalation after donning self-contained self-rescue devices and evacuating the smoke-filled area of the mine on May 18, the breathing apparatus they used were suspected of being faulty.

The Oxyboks K self-rescuers were sent to an independent test house at the Department of Primary Industries in New South Wales.

At the time of the incident, Xstrata spokesman James Rickards told ILN that at least one unit was faulty, while Construction, Forestry, Mining and Energy Union health and safety representative Tim Whyte said four units had failed, and called for a state-wide recall of the whole batch of Oxyboks K’s.

Whyte said yesterday the information he had received from the mine and the DPI was that one of the units tested returned “far above normal and excessive C02 levels”

“Yes there were high levels of CO2, but that is not related to the function of the unit, that is related to the unit being older than 10 years and having already been opened for one and a half weeks before being tested at DPI,” Draeger Safety’s Klaus Schroeter told ILN.

He said the tests confirmed none of the units were faulty and that they are safe to be operated when used correctly.

“We can say, whatever happened up there, it had nothing to do with our units,” he said.

“There are lots of circumstances increasing the CO2 concentration which are not related to the unit itself … there are a few details which we don’t know, like how the unit was handled and stored at Oaky Creek.

“The performance tests showed that the starter worked, the oxygen concentrations were at the right levels, but it cannot be determined where the high CO2 levels came from,” he said.

The units are now being tested further by the DPI to determine whether the problems lie in the units being expired, inadequate SCSR training or another fault.

In November last year, 12 miners from Crinum underground mine, north of Emerald, were taken to hospital when they reported difficulty breathing and feeling ill after using SCSRs during a routine emergency exercise.

“It is believed the men inhaled a higher than normal concentration of CO2 from their breathing apparatus and were also suffering from the effects of walking out of the mine, which was a 1.4km climb up the incline wearing the apparatus," BMA spokesman Ian Dymock said.

“It was a situation that occurred as a result of overexertion in this particular circumstance, but proper use of the apparatus will be reinforced again at training."