Transcript Working In Cold Environments

Working In Cold Environments
Things to Consider
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Where is cold a problem?
Effects of cold on the body
Regulations covering cold
Risk Assessment
Controls
Where is cold a problem?
• Outside work
• Food production
– Chilled
– Frozen
• Controlled environments
• Warehousing
• Winter driving
Why Be Concerned?
• The body needs to maintain a core
temperature of 37C. This thermal
balance must be maintained.
How is heat lost from the body?
• Radiation
• Difference in Temp between body and
surrounding environment. Greater the more
skin is exposed
• Conduction
• Heat loss through direct contact with cooler
object.
How is heat lost from the body?
• Convection
• Loss of heat to the surrounding air as the air
moves across the surface of the skin. Heat loss
depends upon air temperature and wind
speed. Wind speed ceases to have an
increased effect above 50mph
How is heat lost from the body?
• Evaporation
• Heat loss due to the conversion of water from
a liquid to a gas
– Sweating – to remove excess heat
– Insensible perspiration – to maintain humidity of
70% next to skin. Particularly in cold dry
environment
– Respiration – as heated air enters the lungs and is
exhaled with an extremely high moisture content
Thermal Balance
• To survive in cold the body must
balance the heat losses with the heat
production of the body
• To look at this we must consider the
Cold Challenges on the body. These
are:
– Temperature
– Wind
– Wetness
Thermal Balance
Heat Production
- Food Intake
- Activity
- Shivering
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Heat Retention
- Decreased Superficial
Blood Flow
- Clothing
=
Cold Challenge
Hypothermia
Heat Production
- Food Intake
- Activity
- Shivering
+
Heat Retention
- Decreased Superficial
Blood Flow
- Clothing
<
Cold Challenge
Personal Factors
• Size and shape of the body (surface to
volume ratio)
• Layer of fat under the skin
• Decreased the blood flow through the
skin and outer parts of body
• Insulation (layering and type of
clothing)
Personal Factors
• Response in Men and Women
– Core cools more slowly in women.
However, they are not able to create as
much metabolic heat
– Extremities cool more quickly in women
– As a result women are at a greater risk of
cold injury
Personal Factors
• Predisposing conditions
– Age – old and very young
– Diseases of the blood circulatory system
– Injuries resulting in blood loss or altered
blood flow
– Previous cold injury
– Fatigue
– Consumption of alcohol or nicotine
Personal Factors
• Acclimatisation
– People do not acclimatise to cold very
well
– Frequently exposed body parts can
develop some degree of tolerance to the
cold
Effects of cold on the body
• Impairment of complex mental
processes
• Manual tasks impaired due to loss of
dexterity
• Blood redirected from extremities to
keep core warm
• Reduced muscular strength
Effects of cold on the body
• Stiffened joints
• Reduced mental alertness
• Corneas of eyes can freeze with high
wind chill
• Cold injuries
Cold injuries
• Non freezing
• Freezing
• Hypothermia
Non Freezing Injuries
• Chilblains
• Mild injury caused by prolonged and repeated exposure
for several hours to air tempretures from 0c to 16c.
Redness of skin, swelling, tingling and pain
• Immersion foot
• Where foot has been wet but not freezing cold for days
or weeks. Can occur up to 10c. Primary injury to nerve
and tissue. Symptoms include tingling, numbness,
itching, pain, swelling of legs, feet or hands, Blisters
may develop. Gangrene can develop
Non Freezing Injuries
• Trenchfoot
• Wet cold disease. Similar to Immersion Foot
but occurs at lower temperatures. Onset can
range from hours to many days. Average three
days.
Freezing Injuries
• Frostnip
• Mildest form of freezing injury. Occurs when ear lobes,
noses, cheeks, fingers or toes are exposed to cold and
top layers of skin freeze. Affected area turns white and
feels numb
• Frostbite
• Common injury on exposure to extreme cold or contact
with extremely cold objects. May occur on contact with
cold gases. Occurs when tissue temp falls below 0c or
blood flow is obstructed. Blood vessels can be severely
and permanently damaged. In mild cases symptoms
include inflammation of skin accompanied by slight
pain. Severe cases can lead to burning or prickling
sensations resulting in blisters. Frostbitten skin is
susceptible to infection leading to gangrene. Can lead
to amputations
Hypothermia
• This is the condition that is caused by
the bodies core temperature dropping.
• First symptom is feeling of cold and
pain in exposed parts of body
• As temp drops the feeling of cold and
pain diminishes
Hypothermia
• Muscular weakness and drowsiness are
experienced. This is the onset of the
hypothermia and occurs when the core temp
reaches 33c
• Additional symptoms include: interruption of
shivering, diminished consciousness and
dilated pupils
• 27c coma, 20c heart stops, 17c brain stops
Stage
Core Temp
Signs & Symptoms
Mild
Hypothermia
37.2 – 36.1c
Normal Shivering May Begin
36.1 – 35c
Cold sensation, goose bumps, unable to perform complex tasks
with hands, shivering can be mild to severe, hands numb
35 – 33.9c
Shivering, intense, muscles in coordination becomes apparent,
movements slow and laboured, stumbling pace, mild confusion,
may appear alert. Use sobriety test, if unable to walk a 30 foot
straight line, the person is hypothermic
33.9 – 32.2c
Violent shivering persists, difficulty speaking, sluggish thinking,
amnesia starts to appear, gross muscle movements sluggish, unable
to use hands, stumbles frequently, difficulty speaking, signs of
depression, withdrawn
32.2 – 30c
Shivering stops, exposed skin blue of puffy, muscle coordination
very poor, inability to walk, confusion, incoherent/irrational
behaviour, but may be able to maintain posture and appearance of
awareness
30 – 27.8c
Muscle rigidity, semiconscious, stupor, loss of awareness of others,
pulse and respiration rate decrease, possible heart fibrillation
27.8 – 25.6c
Unconscious, a heart beat and respiration erratic, a pulse may not
be palpable
25.6 – 23.9
Pulmonary oedema, cardiac and respiratory failure, death. Death
may occur before this temperature is reached
Moderate
Hypothermia
Severe
Hypothermia
Regulations
• HSaW Act 1974 – General Duties – Safe
working Environement
• Management Regs – Reg 3 Risk
Assessment
• Workplace Regs – Reg 7 – Tempreture
in all workplaces inside buildings shall
be reasonable during working hours
Regulations
• Acop goes on to suggest minimum
levels of:
• 16c sedentary work
• 13c physical effort
• Acop allows for special circumstances
such as food where lower temps are
required and it is impractical to take
other steps – localised chilling etc.
Risk Assessment
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Use the normal hierarchy
Is cold process required?
Can exposure to cold be prevented?
Consider how people may be affected
by the cold?
• Select suitable controls for residual
risk
• First Aid Risk Assessment
Controls
• Warm working station within cold area
• Exposure product to warm room for
short period
• Pre-chill products
• Chilling stations on line
• Floor matting to raise feet off cold
floors
Controls
• Suitably heated rest rooms
• Work rest regimes to limit time spent
in cold area
• PPE – free to user and suitable for
conditions
• Training for First Aiders
Further information
• BS7915:1998 Ergonomics of the thermal
Environment – Guide to the design and
evaluation of working practices for
cold indoor environments
• HSE Information Sheet – FIS3(rev1)
March 1999