The 29 miners lost in the Pike River disaster would have died within minutes of the original explosion at the mine, a coronial inquest has heard.
Superindendent Gary Knowles told the inquiry today that expert evidence from Dr Robin Griffiths of the University of Otago showed the first blast on November 19 would have released a lethal combination of carbon monoxide and carbon dioxide.
All 29 miners would have died within five minutes, the inquiry heard.
"The chances they would have lived would have been nil.
"In the presence of such low oxygen hypoxic hypoxia would have occurred rapidly.
"They would have remained unconscious until death three to five minutes later."
Chief Coroner Neil MacLean opened the coronial inquest into the Pike River mine disaster just after 10am.
He told family representatives the inquest would focus on the facts surrounding the miners' deaths but may not "go too far as to the exact location".
Mr Knowles earlier read out a list of all the miners and the last time they were seen before they died.
Many of the miners were last seen by family on November 19 - the morning of the explosion.
Tale of heroism
Mr Knowles told the court one of the men in the mine, Daniel Rockhouse was working about halfway into the mine when the blast happened.
Mr Rockhouse saw a "white flash", was blown off his feet, and was deafened by the noise.
The mine filled with smoke, Mr Knowles said.
He was able to put a gas mask on, but panicked and fell unconscious for about 20 minutes.
When Mr Rockhouse awoke he was able to get to an oxygen valve and also rang the mine base to alert them to the explosion.
"He made his way back out of the mine where he came across another miner, Russell Smith," Mr Knowles said.
Mr Smith was semi-conscious but unable to put a gas mask on, so Mr Rockhouse picked him up and dragged him further back down the mine shaft.
When Mr Smith was recovered enough he was able to walk by himself.
The pair kept stopping on their way back to check for light and any sign of life, but none could be seen, Mr Knowles said.
Purpose of inquest
Family members, friends and media filled the small Greymouth District Court building this morning on a cloudy, rainy West Coast day.
A spokesman for Judge MacLean yesterday said the inquest would be limited to establishing the time and cause of the men's deaths, and formally confirming their identities to allow death certificates to be issued.
Wider issues concerning the cause and possible prevention of the mine tragedy would be covered later by a Royal Commission of Inquiry.
The coroner is expected to hear evidence from four expert witnesses, as well as police and Pike River Coal representatives.
"Their evidence will help him determine as far as possible the time and manner of death, and if he can do that, that will allow the issuing of death certificates," the spokesman said.
The coroner anticipated making an oral finding on the time and cause of death at the end of proceedings. He would then adjourn the inquest indefinitely so as not to prejudice the Royal Commission.
However, Judge MacLean could re-open the inquest later if necessary.
"He will...let the Royal Commission take its course and then if he feels any need to re-open his inquest, he will. Otherwise he will just close it," the spokesman said.
The hearing is set down today, and tomorrow if required.
- NZHERALD STAFF and NZPA