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Cold
Stress |
The Occupational Safety and Health Act (OSH Act) requires employers to comply with hazard-specific safety and
health standards. In addition, pursuant to Section 5(a)(1) of the OSH Act, employers must provide their employees with a workplace
free from recognized hazards likely to cause death or serious physical harm. Emergency Preparedness Guides do not and cannot enlarge or
diminish an employer's obligations under the OSH Act.
Emergency Preparedness Guides are based on presently available information, as well as current occupational safety and health provisions
and standards. The procedures and practices discussed in Emergency Preparedness Guides may need to be modified when additional, relevant
information becomes available or when OSH Act standards are promulgated or modified. |
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During emergency response activities or recovery operations, workers may be
required to work in cold environments, and
sometimes for extended periods. Cold
stress is a common problem encountered in these types of situations. The
following frequently asked questions will help workers understand what cold stress is, how it may affect their health
and safety, and how it can be prevented.
How cold is too cold?
When the body is unable to warm itself,
cold related stress may result. This may include tissue damage
and possibly death. Four factors contribute to cold stress: cold air
temperatures, high velocity air movement, dampness of the air, and contact with
cold water or surfaces. A cold
environment forces the body to work harder to maintain it's temperature.
Cold air, water, and snow all draw heat from the body. Wind
chill is the combination of air temperature and wind speed.
For example, when the air temperature is 40°F, and the
wind speed is 35 mph, your exposed skin receives conditions
equivalent to the air temperature being 11° F. While it is obvious
that below freezing conditions combined with inadequate clothing
could bring about cold stress, it is also important to understand
that it can also be brought about by temperatures in the 50's
coupled with some rain and wind.
How does the body react to cold conditions?
When in a cold environment, most of your body's energy is used
to keep your internal temperature warm. Over time, your body
will begin to shift blood flow from your extremities (hands,
feet, arms, and legs) and outer skin to the core (chest and abdomen).
This allows exposed skin and the extremities to cool rapidly
and increases the risk of frostbite and hypothermia. Combine
this with cold water, and trench foot may also be a problem.
What are the
most common cold induced problems?
Hypothermia, Frostbite, and Trench Foot.
What is
Hypothermia?
Hypothermia which means "low
heat", is a potentially serious
health condition. This occurs when body heat is lost faster than it can be replaced. When the
core body temperature drops below the normal 98.6° F to around
95° F, the onset of symptoms normally begins. The person
may begin to shiver and stomp their feet in order to generate heat. Workers
may lose coordination, have slurred speech, and fumble with items
in the hand. The skin will likely be pale and cold. As the body
temperature continues to fall these symptoms will worsen and
shivering will stop. Workers may be unable to walk or stand.
Once the body temperature falls to around 85° F severe hypothermia
will develop and the person may become unconscious, and at 78°,
the person could die.
Anyone working in a cold environment may be at risk for cold
stress. However, older people may be at more risk than younger
adults, since older people are not able to generate heat as quickly.
Certain medications may prevent the body from generating heat
normally. These include anti-depressants,
sedatives, tranquilizers and
others.
Treatment depends on the severity of the hypothermia. For cases
of mild hypothermia move to warm area and stay active. Remove
wet clothes and replace with dry clothes or blankets, cover the
head. To promote metabolism and assist in raising internal core
temperature drink a warm (not hot) sugary drink. Avoid drinks
with caffeine. For more severe cases do all the above, plus contact
emergency medical personnel (Call 911 for an ambulance), cover
all extremities completely, place very warm objects, such as
hot packs or water bottles on the victim's head, neck, chest
and groin. Arms and legs should be warmed last. In cases of severe hypothermia treat the worker very
gently and do not apply external heat to re-warm. Hospital treatment is required.
If worker is in the water and unable to exit, secure collars,
belts, hoods, etc. in an attempt to maintain warmer water against
the body. Move all extremities as close to the torso as possible
to conserve body heat.
What is
Frostbite?
Frostbite occurs when the skin actually freezes and loses water.
In severe cases, amputation of the frostbitten area may be required.
While frostbite usually occurs when the temperatures are 30° F
or lower, wind chill factors can allow frostbite to occur in
above freezing temperatures. Frostbite typically affects the
extremities, particularly the feet and hands. The affected body
part will be cold, tingling, stinging or aching followed by numbness.
Skin color turns red, then purple, then white, and is cold to the touch. There may be blisters in severe cases.
Do not rub the area to warm it. Wrap the area in a soft cloth,
move the worker to a warm area, and contact medical personnel.
Do not leave the worker alone. If help is delayed, immerse in
warm (maximum 105 °F), not hot, water. Do not pour water
on affected part. If there is a chance that the affected part
will get cold again do not warm. Warming and recooling will cause
severe tissue damage.
What is Trench
Foot?
Trench Foot or immersion foot is caused by having feet immersed
in cold water at temperatures above freezing for long periods of time. It is similar to frostbite,
but considered less severe. Symptoms usually consist of tingling,
itching or burning sensation. Blisters may be present.
Soak feet in warm water, then wrap with dry cloth bandages. Drink
a warm, sugary drink.
What preventive measures should I take?
Plan for work in cold weather. Wearing appropriate clothing and
being aware of how your body is reacting to the cold are important
to preventing cold stress. Avoiding alcohol, certain medications
and smoking can also help to minimize the risk.
Protective Clothing is the most important way to avoid cold stress.
The type of fabric also makes a difference. Cotton loses its
insulation value when it becomes wet. Wool, on the other hand,
retains its insulation even when wet. The following are recommendations
for working in cold environments:
- Wear at least three layers of clothing. An outer layer
to break the wind and allow some ventilation (like Gortex® or
nylon). A middle layer of down or wool to absorb sweat and
provide insulation even when wet. An inner layer of cotton
or synthetic weave to allow ventilation.
- Wear a hat. Up to 40% of body heat can be lost when the
head is left exposed.
- Wear insulated boots or other footwear.
- Keep a change of dry clothing available in case work clothes
become wet.
- Do not wear tight clothing. Loose clothing allows better
ventilation.
Work Practices and
planning are important preventative measures.
Drink plenty of liquids, avoiding caffeine and alcohol. It is
easy to become dehydrated in cold weather. If possible, heavy
work should be scheduled during the warmer parts of the day.
Take breaks out of the cold. Try to work in pairs to keep an
eye on each other and watch for signs of cold stress. Avoid fatigue
since energy is needed to keep muscles warm. Take frequent breaks
and consume warm, high calorie food such as pasta to maintain
energy reserves.
Engineering controls can be effective in
reducing the risk of cold stress. Radiant heaters may
be used to warm workers. Shielding work areas from drafts or
wind will reduce wind chill. Use insulating material on equipment
handles, especially metal handles, when temperatures drop below
30° F.
Training in recognition and treatment
is important. Supervisors, workers and coworkers should watch
for signs of cold stress and allow workers to interrupt their
work if they are extremely uncomfortable. Supervisors should
also ensure that work schedules allow appropriate rest periods
and ensure liquids are available. They should use appropriate
engineering controls, personal protective equipment and work
practices to reduce the risk of cold stress. All of these measures
should be incorporated into the relevant health and safety plans.
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Last Updated: 23 February 2005
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