CONFINED HAZARDS
COMMON AND NOT SO COMMON
CONFINED SPACE
HAZARDS
H
azards present in everyday
workplaces can be found in a
confined space. The confined
space makes controlling the
hazards that much more
critical.
THESE HAZARDS INCLUDE THE
FOLLOWING:
1. Oxygen-deficient or oxygen-rich
atmospheres. Some gases can be so
concentrated that they displace oxygen.
Gases lighter than oxygen, heavier than
oxygen, or even something like carbon
monoxide (.96 specific gravity) can have
oxygen displacement effects through
6
the depth or width of a confined
space. Health signs and symptoms
of low oxygen levels below 19.5
percent include increased respiration,
increased heart beats per minute, loss
of coordination, mental confusion, and
fatigue. Even lower oxygen levels result
in signs like nausea, vomiting, loss of
motor functions, convulsions, loss of
consciousness, and even death. Argon,
nitrogen, and carbon monoxide are
common gases that displace oxygen in
a confined space. Hydrogen sulfide is
heavier than air and has the ability to
disable the olfactory glands at 100–150
parts per million. The smell goes away
but the gas remains. Atmospheric
testing should be used to maintain
oxygen levels above 19.5 percent and
below 23 percent.
2. Fire hazards from a flammable or
explosive atmosphere may exist
because of flammable liquids, vapors,
or combustible dusts. Six-foot, steel-
reinforced walls in grain elevators
have been torn apart because of
combustible dust explosions. These
hazards become even more dangerous
in the presence of an oxygen-enriched
atmosphere. Atmospheric testing