Workers sometimes have to enter spaces that were not designed for humans at
all. Silos, vats, hoppers, utility vaults, tanks, sewers, pipes, aircraft wings
and other "confined spaces" may be difficult to exit and are often fraught with
They may lack oxygen and contain poisonous substances, making it dangerous for
the worker to breathe. Sometimes, explosive or flammable gases accumulate in
confined spaces without the worker realizing it, and could cause a fire or
explosion if ignited. Confined spaces may be very hot or very cold, offer
limited visibility, and contain various other physical, chemical, biological or
Each year, workers are injured or killed while working in confined spaces. Of
particular concern are the poisonous gases in some confined spaces that can
kill a person without warning. Hydrogen sulfide, for example, may be impossible
to detect since at high concentrations, it reduces the person's ability to
smell the tell-tale rotten egg odour of this gas. Too often the victim count is
increased because someone has entered a confined space in an attempt to save a
co-worker who has fallen unconscious or is in some other danger. These would-be
rescuers often succumb to the hazardous conditions themselves, and represent an
estimated 60 percent of fatalities in confined spaces. Such was the case in the
recent fatalities at the Sullivan lead-zinc Mine in British Columbia in which 2
of the 4 dead were paramedics.
Before entering a workspace, workers should stop to consider whether or not it
is a confined space:
If it is a confined space, the company should consider doing the work outside
of that space, if at all possible.
The air within a confined space should be tested before a person enters. The
testing is done from outside of the confined space. A trained worker, using
appropriate detection equipment, samples the air throughout the confined space.
Before a person enters, the air testing should show a safe amount of oxygen,
and absence of any toxic or flammable gas. If the space cannot be made safe, no
person should enter.
Working in a confined space requires special training. For example it also
requires a good understanding of gas monitoring, ventilation systems, fire and
explosion prevention, equipment lockout, and a thorough knowledge of the
worksite's specific hazards.
AplusA-online.de - Source: Canadian Centre for Occupational Health and Safety