Chapter 7 - Cold _ Heat Stress in OIl _ Gas Industry

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EG313 – Safety in Oil & Gas Industry
Chapter 7
Cold & Heat Stress in Oil & Gas Industry
Contents
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• Heat and body mechanism
• Cold stress
• Heat stress
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Introduction – Cold Stress
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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
Body Heat
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Maintaining Temperature: Balancing Heat Loss and 
Heat Production
Most of the body’s energy is used to maintain
an internal (core) body temperature of 
approximately 98.6°F (37°C). 
• Heart
• Brain
• Lungs
• Liver
• Kidneys
Body’s 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.
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Body Heat
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Maintaining 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.
Challenges From Cold Conditions
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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 mph and higher), blown air 
from fan in cold rooms, etc.
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Wind Chill Effect
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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. 
Wind Chill Effect
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• Example: When the air temperature is 15°F (-9 °C) and wind 
speed is 10 mph, your exposed skin receives conditions 
equivalent to the air temperature being 0°F (-17 °C). Frostbite 
will develop in 30 min.
• If the wind speed doubles to 20 mph, it will feel like it is -18°F 
(-27 °C) and frostbite will occur in only 10 minutes.
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Wind Chill Effect
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CONDUCTION:
Heat loss through contact with a cooler object - 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)
How Does the Body Lose Heat?
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EVAPORATION: 
Heat loss in the form of 
vapor when body uses 
heat to evaporate 
moisture from skin 
surface (perspiration or 
“sweat”)
CONVECTION:
Heat loss when one of 
the objects is in motion. 
Eg: from wind (blown 
air from fan, etc.) or 
water; rate of heat loss 
depends on density of 
moving substance.
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 
<98.6°F)
RESPIRATION: 
Heat loss from 
lungs’ warming 
inhaled cold air, 
which is then 
exhaled
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How Does the Body Produce Heat?
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• 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 
body’s heat production; limited to a few hours because 
of depletion of muscle “fuel” stores and the onset of 
fatigue.
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:
How Does the Body Produce Heat?
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• Food intake 
• "Fuel" (glycogen or 
carbohydrates) store 
• Fluid balance (water in = 
water out)
• 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)
Factors important in heat 
production:
Factors influencing heat 
retention and tolerance to 
cold:
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Cold Stress
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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 doesn’t only 
happen when conditions are 
below freezing; it can also be 
brought about by temperatures 
in the 25°C with some rain and 
wind.
How Does Cold Affect Work Performance?
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► Lower work 
efficiency
► Higher
accident rates
Uncomfortably cold working conditions
(combination of temperature, wetness, wind)
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
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Cold Injuries / Illnesses
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• 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 body’s ability to regulate temperature 
and increases risk for hypothermia 
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: 
Factors Increasing Risk of Cold Injuries/Illnesses
Cold Injuries / Illnesses
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• Hypothermia is a potentially fatal condition, occurs when 
body temperature falls below 95°F (35°C).
• Frostbite, frostnip, chilblains, and immersion injury most 
commonly affect the extremities - toes, fingers, ears, nose
Working in freezing conditions or under prolonged exposures to 
temperatures below freezing, along with other factors, can cause 
cold-related injuries and illnesses, tissue damage, possible 
amputation, or death.
Hypothermia Frostbite
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Preventive Measure
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 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. 
Planning
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• 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 be looked up in the wind chill chart.
Monitor temperatures and air movement
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Engineering Controls
19• 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.
Clothing
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• Body: Wear at least three layers of loose-fitting clothing to trap air 
and provide insulation, and allow better ventilation.
1. Inner wicking layer made from polyester, 
polypropylene, or other synthetic material 
that draws moisture away from the skin 
and helps keep it dry. 
2. Middle insulating layer made of wool, down, 
fleece, or other material with loft that will 
hold the body’s heat.
3. 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. 
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Clothing
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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. 
Personal Protective Equipment
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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
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Work Practice to Reduce Cold Risk
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• Pace the work to avoid excessive sweating. Change into dry clothes if 
clothes become wet. New employees should be given enough time to 
adjust 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 or rice to maintain energy reserves.
Working in the cold requires more energy to
maintain body heat.
Work Practice to Reduce Cold Risk
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• 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 40°F. These 
materials in contact with the skin greatly increase heat loss from the 
body.
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Training
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• 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.
Heat Stress
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Workplace Heat Illness (Heat Stress) 
Prevention
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Training
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• Prior to work in warm weather, supervisors and employees 
shall be trained on the following:
– The department’s heat illness prevention procedures
– Environmental and personal risk factors for heat illness
– The importance of consuming water throughout the work 
shift
– The importance of acclimatization.
– Common signs/symptoms of heat illness
– The importance of reporting sign/symptoms of heat illness 
to the supervisor
– Emergency response procedures
Heat Illness
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Risk Factors for Heat Illness
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• Weather conditions
– Temperature
– Humidity
– Air movement
– Radiant heat (ex: sunshine)
– Conductive heat (ex: ground)
• Higher intensity and/or duration
of physical activity
• PPE / clothing can be a factor
(i.e., tyvek overalls) 
Personal Risk Factors
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• Poor physical condition*
• Age
• Degree of acclimatization
• Water consumption
• Some medications*
• Alcohol/ drugs
* Recommend checking w/ personal physician about heat illness risk
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How Does the Body Handle Heat
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• The body tries to keep a constant internal 
temperature
• As internal temperature rises from activity, the 
body cools itself by:
– Increasing blood flow to skin surface
– Releasing sweat onto skin surface
Heat Exhaustion
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• Cause: 
– Excessive loss of water and salt through 
sweat
• Signs & Symptoms:
– Headaches, dizziness, lightheadedness 
or fainting
– Weakness and moist skin
– Muscle cramps
– Mood changes such as irritability or 
confusion
– Upset stomach or vomiting
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Heat Stroke
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• Cause: 
– Total breakdown of body’s cooling system
• Signs & Symptoms:
– Sweating stops-- skin is hot, red, and dry
– Mental confusion, losing consciousness
– Fainting
– Seizures or convulsions
Treat as a medical emergency! Can be life 
threatening
Heat Stroke
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Emergency Response Procedure
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For any of the previously mentioned symptoms:
• Immediately call 911/999
• While waiting for help:
– Move victim to cool area
– Give small cup of water (if conscious and not nauseous)
– Loosen and/or remove clothing
– Fan and mist the person w/ water
– Apply a water-soaked towel (or ice pack wrapped in towel) to head and 
ice pack to armpits
• Contact supervisor immediately!
• Anyone with symptoms must never be sent home or left unattended 
without a medical evaluation.
• Follow-up for employees evaluated for heat illness.
Prevention of Heat Illness
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Access to Water
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• Access to sufficient 
amounts of cool drinking 
water shall be available 
at all times.
• Recommend consuming 
at least four cups per 
hour for the entire shift.
Access to Shade
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• A shaded rest area shall be 
provided as close as 
practicable to the work area.
• As needed, take frequent 
cool-down breaks in the 
provided shade. 
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Work Planning and Supervision
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• Assess weather conditions:
– Weather forecasts 
– Current weather
• Note: high humidity drives up the 
heat load
• For warmer periods:
– Schedule outdoor work during 
cooler parts of the day
– For most strenuous tasks, plan a 
staff rotation
Work Planning and Supervision
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• Worker acclimatization
– People adapt to outdoor temperature increases 
within 4-14 days.
– To minimize the risk of heat illness:
• Adjust work schedules and intensities during a 2-week 
period
• New employees or those returning from extended 
leaves – acclimatization is especially important
– May not be adapted to local weather or work intensity
– Be extra vigilant withthese employees
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Work Planning and Supervision
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• For outdoor temperatures ≥85°F (29 °C), supervisors shall ensure:
• Shade is present for employee rest breaks. 
– When a worker has brief periods of outdoor work without nearby 
shade, the employee shall be instructed on how he/ she will be able to 
quickly access shade as needed for heat illness prevention
– If it is not safe or feasible to provide shade, document why the shade 
cannot be provided and what steps will be taken to provide shade upon 
request or an alternative cooling measure with equivalent protection.
• Staff are reminded throughout the day to drink plenty of water and to take 
cool-down breaks in the shade (when they feel the need to do so).
• Effective means for employees to contact the supervisor and emergency 
services.
• Regular monitoring of employees for alertness and signs/symptoms of heat 
illness.
• Close supervision of new employees.
Written Procedure
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• These steps detail how your personnel will locally:
• Provide supervisor and employee training
• Provide access to water & shade
• Monitor employees and report signs/symptoms of heat illness
• Respond to heat illnesses without delay, provide first aid and emergency 
services.
• Provide clear and precise directions to the worksite.
• Train all supervisors and employees on these procedures. 
• Document training conducted
• Maintain the procedures on-site or close to the site, so that it can be made 
available to representatives of Cal/OSHA upon request.
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Summary of Supervisor Responsibilities
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• Obtain heat illness prevention training
• Be aware of your staff’s heat stress potential
• Develop and train staff on written local heat illness 
prevention procedures
• Provide access to water and shade.
• Plan and manage work activities accordingly to reduce 
the risk of heat stress
• Be able to recognize any warning signs of heat illness
– Promptly respond to symptoms of heat illness!
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Emergency Response
Thank You