After as little as one or two days, the air around a cargo of wood products can be lethal to inhale. This is indicated by measurements made near wood product cargoes in 2007.
During the last two years, seven people have died in accidents in sealed areas onboard ships associated with Sweden. In particular, a number of cargo ships carrying wood products have been involved.
In order to gain more knowledge about organic cargoes, a Swedish-Canadian research project was started last year under the leadership of Urban Svedberg at the Occupational and Environmental Clinic of Medicine at Sundsvall Hospital. Wood products such as pulpwood, chips and pellets have been examined and some of the results obtained came as a shock to the researchers.
Cargoes of pellets produce lethal carbon monoxide
– What surprised us most was that the carbon monoxide level was so high in cargoes of pellets and that the levels of oxygen seemed to decrease so quickly in spaces where pulpwood and chips were stored. In only one or two days the air had become lethal, says Urban Svedberg.
Wood product cargoes all created harmful atmospheres, but this took place through different processes and gave different results. When wood pellets are stored, carbon monoxide – a very toxic gas – is produced. When carbon monoxide gets into the lungs it prevents the body from absorbing oxygen from the air and for this reason it does not necessarily help the victim to get out into fresh air.
– If the oxygen content alone is measured in a space you may be deceived into thinking that the air is harmless. In fact, it may be sufficient to breathe in a few times to lose consciousness and die within a couple of minutes. It is a kind of inner suffocation, says Urban Svedberg.
When wood chips and pulpwood are transported, other processes are initiated. First and foremost it is oxygen in the air that is quickly consumed.
– The oxygen disappears extremely quickly, and according to our measurements cargoes of wood chips and pulpwood may become lethal after 48 hours, possibly after as little as 24 hours, says Urban Svedberg.