A DAD-OF-TWO could have been dead in less than a minute after going into a chemical reactor, an inquest heard.

On the third day of the hearing into the death of Nicholas Shone, 35, from Marsden, it was revealed there could have been virtually no oxygen when he went into the tank at Grosvenor Chemicals in Linthwaite last October 8.

The Bradford inquest had already heard how Mr Shone, of Woods Avenue, had gone against rules and advice to enter the tank to retrieve a piece of hosepipe.

The tank had been used for mixing chemicals for the pharmaceutical industry and was full of nitrogen gas.

The man responsible for investigating the circumstances of Mr Shone's death for the Health and Safety Executive, Neil Martin, told the jury of five men and five women yesterday he believed Mr Shone had taken a risk without knowing all the facts.

He added: "In my opinion he took a calculated risk in the light of the knowledge he had. He may not have appreciated the risk of a low oxygen environment."

Coroner Roger Whittaker asked Mr Martin if Mr Shone would have realised the tank would have been `oxygen deprived'.

Mr Martin said: "He would have been aware it was a nitrogen atmosphere because of the nature of the process of working with flammable vapours.

"It is a routine process to keep the vessel inert with a nitrogen atmosphere."

Mr Martin added: "Maybe he believed he could do it just by holding his breath. But we shall never know."

The inquest also heard from the head of personal and protective equipment section of the HSE's laboratory.

Dr Nicholas Vaughan said he had received two items for examination as a result of Mr Shone's death.

These were an Arco Filtermax 2 gas mask and a Tornado respirator.

Dr Vaughan said the Arco mask would keep out the chemicals, such as solvent isopropanol and acetic acid, which were in the tank.

He also said that despite the full-face mask having a broken strap and scratches the filter part of the equipment would have worked.

In the Tornado respirator, which pumps air to a face-mask from a waist-mounted filter unit, he discovered an outlet valve had been kept open at all times with tissue. This mask was also working. But he added: "No filtering device can protect against oxygen deficiency."

Dr Vaughan said the air inside the tank had only 12% oxygen 12 hours after the incident. The normal oxygen level in air is just under 21%.

When asked by the coroner whether the level of oxygen at the time of the accident could be virtually nothing, he replied: "It could."

Dr Vaughan said the maximum theoretical time Mr Shone could have been alive in the tank was three minutes.

But he said that the body recognises carbon dioxide as a problem for breathing - not nitrogen. He said Mr Shone would just have collapsed.

When asked by lawyer Stephen Glover, for Grosvenor, how quickly it could have been Dr Vaughan agreed it was likely that it was less than a minute. He added: "Just a couple of breaths and out."

The inquest continues.