Lethal Carbon Monoxide Poisoning in Wood Pellet Storerooms

The installation of wood pellet heating as a cost-effective and climatically
neutral source of energy has increased steadily in recent years. The authors
report two deaths that occurred within the space of about a year in wood pellet
storerooms of private households in German-speaking countries and were
investigated by forensic medical teams. This is the first report of fatalities
in this special context as is shown in the literature review. Both victims died
of carbon monoxide (CO) poisoning; one of the victims was a woman who was 4
months pregnant.

Measurements at the scene detected life-threatening CO concentrations (7500
ppm, >500 ppm), which were not significantly reduced after ventilation of the
storerooms as required by regulations. The authors carried out a series of
experiments in order to confirm CO production by wood pellets. Thirty kilograms
of freshly produced pellets from two different manufacturers were stored for 16
days in airtight containers at 26°C with different relative humidities. CO
concentrations between 3100 and 4700 ppm were measured in all containers. There
were no notable differences between the wood pellet products or storage at
different humidities. Emission of CO from wood pellets has already been
described, but fatal accidents have previously been reported only in
association with pellet transport on cargo ships or storage in silos. It is
therefore a new finding that fatal accidents may also occur in the wood pellet
storerooms of private households.

The authors show that significant CO concentrations can build up even when
these rooms are ventilated in accordance with the regulations and that such
levels may cause the death of healthy persons, as described in the following.
As the safety recommendations from the wood pellet industry are inadequate, the
authors consider that further fatal accidents are likely to occur and recommend
urgent revision of the safety regulations.

More information - Source: The Annals of Occupational Hygiene