Wood cargo releases gas

Several deaths in Sweden during discharge of logs and wood chips from ships were blamed on the wood cargo starving the hold of oxygen.

Transport of logs and wood in confined spaces may result in rapid and severe oxygen depletion and carbon dioxide formation, says a study by Swedish occupational medicine researchers reported online.

The primary cause was gases formed by microbiological activity during the decomposition of the wood over time.

Gases produced included carbon monoxide, carbon dioxide, hydrogen sulfide and hydrocarbons.

The study noted this occupational hazard for people entering unventilated stairways in ship's holds was not properly appreciated, despite five reported deaths and several injuries in Swedish ports between August 2005 and May 2007.

Port of Tauranga chief executive Mark Cairns confirmed the port had a safety procedure for entering the holds of vessels with organic cargo, including logs. This was because the cargo consumed oxygen.