Title: Working in Cold Environments:
1Working in Cold Environments Preventing
Cold-related Injuries and Illnesses
2What this presentation covers
- How the body maintains thermal (heat) balance,
constant internal temperature - How the body reacts to cold conditions
- Injuries and illnesses caused by exposure to cold
- Preventive measures to minimize the hazards from
cold exposure
See the module Cold-related Injuries and
Illnesses for more detailed descriptions of
hypothermia, frostbite, and other cold injuries.
3Introduction
- Exposure to cold can occur when working outdoors
or in artificial cold environments. Working for
prolonged periods or in extreme cold conditions
can lead to cold-related injuries and illnesses,
permanent tissue damage, and death.
Examples of artificial cold environments
- Cold storage rooms, refrigerated warehouses
- Freezers
- Refrigerated tractor trailers
4Workers at Risk of Cold Exposure
Examples of industries/jobs at risk of exposure
to cold
- Building, road, and other construction, repair
- Airport ground personnel/ support
- Ski resorts and other outdoor recreation
- Ferries Longshore/dock work
- Fishing, crabbing, diving
- Logging
- Trucking, other transport
- Agriculture and dairy
- Food processing, packing, storage
- Cold storage, warehousing
- Ice making
- Window cleaning
- Police, fire, and emergency response
- Postal, delivery services
- Sanitation/trash collecting
- Utilities, communications
5Maintaining Temperature Balancing Heat Loss and
Heat Production
- Most of the bodys energy is used to maintain an
internal (core) body temperature of approximately
98.6F (37C).
Normal core body temperature 98.6F (37C)
Bodys core area (internal organs, especially
ones vital for survival)
The body does this through balancing heat loss
and heat production. In cold conditions, the
body reduces heat loss and increases heat
production.
- Heart
- Brain
- Lungs
- Liver
- Kidneys
6Maintaining Temperature Balancing Heat Loss and
Heat Production
- Over time, your body will decrease blood flow to
your extremities and outer skin and shift it to
the body core to keep the internal organs warm.
However, this allows exposed skin and the
extremities to cool rapidly and increases the
risk of cold-related injuries, such as frostbite
and hypothermia.
7Challenges from Cold Conditions
- Cold conditions force your body to work harder to
maintain its temperature. The challenges you
face from a cold environment include
- Air temperature
- Wetness rain, snow, ice, humidity sweat wet
clothes water - Air movement wind speed (5 miles per hour and
higher) blown air from fan in cold rooms, etc.
8Wind Chill Effect
- Wind chill is the perceived temperature (what it
feels like) resulting from the effect of wind
(wind speed) in combination with cold air (air
temperature). The combined effect increases the
rate of heat loss from exposed skin. The stronger
the wind at a given temperature, the cooler the
wind chill will be.
(Refer to Wind Chill Chart on next
slide) Example When the air temperature is
-15F and wind speed is 10 mph, your exposed skin
receives conditions equivalent to the air
temperature being -35F. Frostbite will develop
in 30 min. If the wind speed doubles to 20 mph,
it will feel like its -42F and frostbite will
occur in only 10 minutes.
9Example If the temperature is -15F and wind
speed is 10 mph, it will feel like its -35F,
and frostbite will develop in 30 minutes. If the
wind speed doubles to 20 mph, the time for
frostbite to occur drops to only 10 minutes.
Wind Chill Chart
Back toprevious slide
Source National Oceanic and Atmospheric
Administration (NOAA), National Weather Service
10How the Body Loses Heat
RESPIRATION heat loss from lungs warming
inhaled cold air, which is then exhaled
EVAPORATION heat loss in the form of vapor
when body uses heat to evaporate moisture from
skin surface (perspiration or sweat)
RADIATION heat loss from exposed body areas
to the environment due to the difference between
the temperature of the body and that of the
cooler air (when air is lt98.6F)
CONVECTIONheat loss from wind removing the
layer of warm air next to the skin rate of heat
loss depends on wind/air speed
or blown air from fan, etc.
CONDUCTION heat loss through
contact with a cooler object and transfer of heat
to the cooler object increases when in contact
with cold wet objects (generally, conduction
accounts for 2-3 of total heat loss in dry
conditions with wet clothes the loss is
increased 5x, and rate of heat loss is 25x
faster when a person is immersed in cold water)
11How the Body Loses Heat
Each of these means of heat loss can play a large
or small role in the development of a
cold-related injury. In addition to air
temperature, air movement (wind speed), and
wetness, the skin surface area that is exposed to
the cold is a factor in the amount of heat lost
from the body.
Factors in heat loss
- Air temperature, wind speed, wetness
- Area of skin surface exposed to cold
(particularly in radiation) - Contact with cold water or surfaces
12How the Body Produces Heat
Your body must produce an equal amount of heat to
counter-balance the heat loss in order to survive
and stay active in the cold. Heat is produced
in the following ways
- Metabolism biochemical reactions in the body
which produce heat as a by-product - Physical Activity (exercise/work) muscles
produce most of the heat during physical work
- Shivering inefficient quivering of the muscles
that increases the bodys heat production
limited to a few hours because of depletion of
muscle fuel stores and the onset of fatigue
13How the Body Produces Heat
Factors important in heat production
Factors influencing heat retention and tolerance
to cold
- Food intake
- "Fuel" (glycogen) store
- Fluid balance
- Size and shape of the body (surface to volume
ratio) - Layer of fat under the skin
- Decreased blood flow through the skin and
extremities - Insulation (clothing)
14Cold Stress
If your body begins to lose heat faster than it
is produced, your core body temperature drops
below normal, and cold stress may result.
Cold stress doesnt only happen when conditions
are below freezing it can also be brought about
by temperatures in the 50's coupled with some
rain and wind.
15How does cold affect work performance?
Uncomfortably cold working conditions (combination
of temperature, wetness, wind)
COLD STRESS
- Immediate signs
- decreased alertness
- restlessness, lack of concentration
- impaired performance of complex mental tasks
- impaired ability to perform manual tasks
- numbness, muscle weakness, stiffened joints
- Lower work efficiency
- Higheraccident rates
16Factors Increasing Risk of Cold Injuries/Illnesses
In general, people in good physical health are
less susceptible to cold injury. In addition to
weather conditions, the following factors may
increase the risk of developing a cold injury
- Previous cold-related injury
- Predisposing health conditions Cardiovascular
disease, Diabetes, Anemia, Sickle cell
disease, Vibration/White finger disease, other
conditions associated with poor circulation,
Hypertension, Asthma - Fatigue, poor physical condition
- Poor nutrition
- Medication Anti-depressants, Sedatives,
Tranquilizers, Others - Alcohol Decreases awareness impairs the bodys
ability to regulate temperature and increases
risk for hypothermia - Caffeine Increases urine production, contributes
to dehydration
17Factors Increasing Risk of Cold Injuries/Illnesses
(Continued)
- Nicotine (Smoking) increases risk for
cold-induced skin injury (such as frostbite,
immersion foot) promotes development of
peripheral vascular disease - Wearing tight clothing restricts circulation
- Under-activity can lead to decreased body heat
production - Over-activity can lead to wet skin, clothing, or
shoes from sweating - Under-dressing exposed fingers, nose, ears
uncovered head - Over-dressing can result in wet skin and
clothing from sweating - Length of exposure
- Age older adults may be at more risk than
younger - Dehydration Causes bodys natural defense
mechanisms to fail and person becomes more
susceptible to cold injuries
18Injuries/Illnesses from Cold Exposure
Working in freezing conditions or under prolonged
exposures to temperatures above freezing, along
with other factors, can cause cold-related
injuries and illnesses, tissue damage, possible
amputation, or death.
- Hypothermia is a serious medical emergency
- Frostbite, frostnip, chilblains, and immersion
injury most commonly affect the extremities -
toes, fingers, ears, nose
19Injuries/Illnesses from Cold Exposure
Injury/Illness Cause
Hypothermia occurs when core body temperature decreases to below 95F can occur in air temperatures below or above freezing (or water temperatures serious medical emergency, can be fatal
Frostbite ice crystal formation in skin and other tissues of the body at or below freezing (32F) causes permanent damage and destruction to blood vessels and other structures, can result in amputation
Frostnip ice crystal formation only in the very outer layer of the skin causes no permanent damage
Chilblains mild cold injury due to prolonged and repeated exposure for several hours to temperatures above freezing (32F to 60F) affected skin is swollen, red, tingly, painful, and itchy
Immersion injury (Trench foot) exposure of wet feet (or hands, other body areas) to cold temperatures over hours to days at or above freezing (32F to 50F) damages nerves and muscles can cause permanent damage
The module Cold-related Injuries and Illnesses
covers these topics at greater depth.
20Preventive Measures
- Planning Plan for work in cold weather and
implement controls to reduce and minimize
exposure and the risk of cold stress. - Planning for the conditions
- Engineering controls
- Work practices
- Appropriate clothing
- Personal protective equipment
- Training Provide training in the recognition and
treatment of cold-related injuries and
illnesses. Supervisors, workers, and
co-workers should watch for signs of cold stress
and allow workers to interrupt their work if they
are extremely uncomfortable. - Awareness Being aware of how your body is
reacting to the cold is important in preventing
cold stress.
21Planning
Monitor temperatures and air movement
- Indoors Take readings of temperature and air
movement in all cold work areas at the start,
middle, and end of each shift, at least every
four hours. - Outdoors The weather report can be used.
Postpone work to a warmer day. Schedule heavy
work during the warmer parts of the day if
possible. - Where there is air movement from wind,
ventilation, or travel in an open vehicle like a
forklift, use the wind chill index to evaluate
the hazard rather than the air temperature. The
wind chill index takes into account the wind
blowing the heat away from the body. If you know
the temperature and speed of air movement, the
wind chill can belooked up in the wind chill
chart.
Click to go to Wind Chill Chart on Slide 9
22Engineering Controls
- Use radiant heaters, warm air jets, and contact
warm plates to warm workers. - Shield work areas from drafts or wind to reduce
wind chill. - Provide heated warming shelters, e.g., tents,
cabins, or rest rooms, for continuous work in
temperatures below freezing. - Cover equipment handles, especially metal handles
and bars, with thermal insulating material when
temperatures drop below freezing (steel conducts
heat away even faster than water). - Design machines and tools so that they can be
operated without having to remove gloves or
mittens. - In refrigerated rooms, minimize air speed as much
as possible with properly designed air
distribution systems. If workers are
simultaneously exposed to vibration and/or toxic
substances, reduced limits for cold exposure may
be necessary.
23Clothing
- The following are recommendations to protect your
body, hands, feet, and head when working in cold
environments
- Body Wear at least three layers of loose-fitting
clothing to trap air and provide insulation, and
allow better ventilation.
- Inner wicking layer made from polyester,
polypropylene, or other synthetic material that
draws moisture away from the skin and helps keep
it dry. - Middle insulating layer made of wool, down,
fleece, or other material with loft that will
hold the bodys heat.
24Clothing
(Continued)
- Body Wear at least three layers of loose-fitting
clothing to trap air and provide insulation, and
allow better ventilation.
- Outer layer for wind and water protection, made
of breathable waterproof fabric that allows
some ventilation (like Gortex or nylon) and is
windproof, and that may also need to be resistant
to oil, fire, chemicals, or abrasion.
Any additional layer(s) of clothing should be
large enough not to compress the inner layers and
decrease the insulation properties.
25Clothing
- Head Wear a wool knit cap or a liner under a
hard hat to reduce excessive heat loss. A mask
also helps protect the cheeks and nose. Up to 40
of body heat can be lost when the head is left
exposed.
26Clothing
- Hands Wear gloves and mittens to prevent
cold-related injuries as well as prevent
accidents and maintain dexterity. The ACGIH
recommends wearing gloves when the air
temperature is - below 60.8F for sedentary work
- below 39.2F for light work
- below 19.4F for moderate work
- below 0F, wear mittens, which protect better
than gloves - Use glove/mitten liners for extraprotection.
- Use fingerless gloves with mittensfor work
requiring dexterity.
The American Conference of Governmental
Industrial Hygienists
27Clothing
- Feet Wear insulated boots with removable felt
liners remove liners daily for complete drying.
Leather mukluk or pack type boots are porous,
allowing the boots to "breathe" and letting
perspiration evaporate. - If work involves standing in water or slush
(e.g., fire fighting, farming), boots must be
waterproof. - If there are crushing hazards, boots must be
steel-toed.
- Wear warm thick socks. If you wear two pairs of
socks, inner liner socks made of polypropylene
will help keep feet dry and warmer (silk, nylon,
or thin wool will work also). Outer thicker
socks should be larger so inner socks are not
compressed.
28Clothing
- (Socks, continued)
- Make sure socks are not too thick this may
result in tightness and loss of insulating
properties, and increase the risk for cold
injuries. If the socks are too thin, the boots
will fit loosely and may lead to blisters. - Change socks if they get wet or damp
General
- Keep clothing dry. Remove snow and moisture from
clothes prior to entering heated shelters.
While resting in a heated area, remove outerwear
to allow perspiration to evaporate. - Keep extra complete change of dry clothing,
shoes, hat, gloves, etc., available in case work
clothes become wet. The body loses heat faster if
skin is in contact with wet clothing, and will
chill rapidly. Excess perspiration will increase
heat loss, so remove extra layers of clothing
whenever you feel too warm.
29Personal Protective Equipment
- Face and Eye Protection
- In extremely cold conditions where face
protection is needed, use eye protection that is
separate from the nose and mouth to prevent
fogging and frosting eye shields or glasses - Wear eye protection appropriate for the work
- Wear eye protection that protects against
- ultraviolet light from the sun
- glare from the snow
- blowing snow/ice crystals
- high wind chill conditions to protect the
corneas of the eyes from potentially freezing
30Work Practices
- Work Practices are important preventive measures.
- Pace the work to avoid excessive sweating. Change
into dry clothes if clothes become wet. New
employees should be given enough time to get
acclimatized to cold and protective clothing
before assuming a full work load. - Avoid sitting or standing still for prolonged
periods. - Take frequent breaks, in shielded areas out of
the cold, to avoid fatigue since energy is needed
to keep muscles warm. - Work in pairs to keep an eye on each other and
watch for signs of cold stress. - Consume warm, high calorie food such as pasta to
maintain energy reserves. Working in the cold
requires more energy to maintain body heat.
31Work Practices
- Drink plenty of warm liquids often, especially
when doing strenuous work, to prevent
dehydration. Avoid caffeine, which increases
urine production and contributes to dehydration. - Avoid alcohol.
- When it is cold, do not brush up against metal
surfaces with bare skin. The skin may stick to it
and get immediate frostbite. - Greases and oils get thick and hard which makes
equipment difficult to use. Follow the proper
procedures and use the right tools. Tools also
get brittle in the cold, so use caution when
working with them. - Avoid skin contact when handling evaporative
liquids (gasoline, alcohol, cleaning fluids)
while de-icing and fueling below 40F. These
materials in contact with the skin greatly
increase heat loss from the body.
32Work Practices
American Conference of Governmental Industrial
Hygienists (ACGIH) Recommended Guidelines
- The following slide shows the ACGIHs
recommendations for working in cold conditions.
The exposure times are based on the wind chill
factor. The work/break schedule applies to any
four-hour period with moderate or heavy activity. - The warm-up break periods are of 10 minute
duration in a warm location. The schedule assumes
that "normal breaks" are taken once every two
hours. - At the end of a 4-hour period, an extended break
(e.g. lunch break) in a warm location is
recommended. - More information is available in the ACGIH
publications "2000 TLVs and BEIs" and
"Documentation of TLVs and BEIs."
33ACGIH Recommended Guidelines
TLVs Work/Warm-up Schedule for Outside Workers based on a Four-Hour Shift TLVs Work/Warm-up Schedule for Outside Workers based on a Four-Hour Shift TLVs Work/Warm-up Schedule for Outside Workers based on a Four-Hour Shift TLVs Work/Warm-up Schedule for Outside Workers based on a Four-Hour Shift TLVs Work/Warm-up Schedule for Outside Workers based on a Four-Hour Shift TLVs Work/Warm-up Schedule for Outside Workers based on a Four-Hour Shift TLVs Work/Warm-up Schedule for Outside Workers based on a Four-Hour Shift TLVs Work/Warm-up Schedule for Outside Workers based on a Four-Hour Shift TLVs Work/Warm-up Schedule for Outside Workers based on a Four-Hour Shift TLVs Work/Warm-up Schedule for Outside Workers based on a Four-Hour Shift TLVs Work/Warm-up Schedule for Outside Workers based on a Four-Hour Shift TLVs Work/Warm-up Schedule for Outside Workers based on a Four-Hour Shift
Air Temperature - Sunny Sky Air Temperature - Sunny Sky No Noticeable Wind No Noticeable Wind 5 mph Wind 5 mph Wind 10 mph Wind 10 mph Wind 15 mph Wind 15 mph Wind 20 mph Wind 20 mph Wind
C (approx) F (approx) Max. work Period No. of Breaks Max. Work Period No. of Breaks Max. Work Period No. of Breaks Max. Work Period No. of Breaks Max. Work Period No. of Breaks
-26 to -28 -15 to -19 (Norm breaks) 1 (Norm breaks) 1 (Norm breaks) 1 (Norm breaks) 1 75 min. 2 55 min. 3 40 min. 4
-29to -31 -20to -24 (Norm breaks) 1 (Norm breaks) 1 75 min. 2 55 min. 3 40 min. 4 30 min. 5
-32 to -34 -25to -29 75 min. 2 55 min. 3 40 min. 4 30 min. 5 Non-emergency work should cease Non-emergency work should cease
-35 to -37 -30 to -34 55 min. 3 40 min. 4 30 min. 5 Non-emergency work should cease Non-emergency work should cease Non-emergency work should cease Non-emergency work should cease
-38 to -39 -35 to -39 40 min. 4 30 min. 5 Non-emergency work should cease Non-emergency work should cease Non-emergency work should cease Non-emergency work should cease Non-emergency work should cease Non-emergency work should cease
-40 to -42 -40to -44 30 min. 5 Non-emergency work should cease Non-emergency work should cease Non-emergency work should cease Non-emergency work should cease Non-emergency work should cease Non-emergency work should cease Non-emergency work should cease Non-emergency work should cease
-43 below -45 below Non-emergency work should cease Non-emergency work should cease Non-emergency work should cease Non-emergency work should cease Non-emergency work should cease Non-emergency work should cease Non-emergency work should cease Non-emergency work should cease Non-emergency work should cease Non-emergency work should cease
Table applies only if workers are wearing dry
clothing and doing moderate to heavy work
activity. For light to moderate work activity,
move down one line to decrease maximum work
period and increase the number of breaks.
2000 TLVs and BEIs - Threshold Limit Values for
Chemical Substances and Physical Agents and
Biological Exposure Indices. Cincinnati
American Conference of Governmental Industrial
Hygienists (ACGIH), 2000 - page 176.
34Training
- Training in recognition and treatment is
important.
- Educate supervisors and workers on
- symptoms of cold related disorders, and signs of
cold stress to watch for - proper clothing habits
- safe work practices
- physical fitness requirements for work in cold
- emergency procedures in case of cold injury
- Allow workers to interrupt their work if they are
extremely uncomfortable. - Supervisors should also ensure that work
schedules allow appropriate rest periods. All of
these measures should be incorporated into the
relevant health and safety plans.
35Resources
- WISHA
- http//www.lni.wa.gov/
- OSHA
- http//www.osha.gov
- NIOSH
- http//www.cdc.gov/niosh/homepage.html
36- Thank you for taking the time to learn about
safety and health and how to prevent future
injuries and illnesses.