Hot and Cold Working Environments

When working in a variety of industries where climate or varying degrees of temperature are a factor, the hazard can not be readily managed using just engineering controls alone. In these circumstances some of the most effective ways of managing these environments is by introducing some simple administrative controls for example:

 Cold working environments

  • Ensure the personal protective equipment issued is appropriate
  • Provision of mobile facilities for re-warming and encourage the drinking of warm fluids such as soup or hot chocolate
  • Introduce more frequent rest breaks
  • For outdoors work, can the job be delayed and undertaken at warmer times of the year without compromising on safety
  • Educate workers about recognising the early symptoms of cold stress.

 Hot working environments

  • Provide more frequent rest breaks and introduce shading to rest areas
  • Provide free access to cool drinking water
  • Encourage the removal of personal protective equipment when resting to help encourage heat loss.
  • Educate workers about recognizing the early symptoms of heat stress
  • For outdoors work, reschedule work to cooler times of the day and
  • Introduce shading in areas where the individuals are working


When the body is unable to cool itself through sweating, serious heat illness may occur. The most severe heat induced illnesses are heat exhaustion and heat stroke. If actions are not taken to treat heat exhaustion, the illness could progress into heat stroke and possibly death.
An excess of heat in the body is termed thermal stress. Heat is exchanged between the body and the environment, using physiological processes. Environmental factors determining the level of heat stress include:

  • air temperature;
  • relative humidity;
  • air movement; and
  • radiant temperature of the surroundings

Heat stress is high in an environment characterised by high ambient temperatures, high humidity and low air movement such as in a sauna. Hot work induces heat stress when more heat is absorbed into the body than can be dissipated. The short-term effects of heat stress are to:

  • reduce concentration and thus promote accidents;
  • aggravate effects of other workplace hazards; and
  • induce heat illness.

The long-term effects of heat stress include chronic heat exhaustion or birth deformities and other reproductive problems.
Some examples of controlling the risk of heat stress using the Hierarchy of Control include:

Control Method Example
Elimination Remove manual labour through mechanised tasks. Design and plan to eliminate manual tasks. Select and purchase equipment with the lowest heat emission rating
Substitution Replace a hot process with a cold one. Acclimatised personnel to replace unacclimatise personnel (new workers; those returning from long breaks e.g. holidays or annual leave)
Isolation Provide a cooled work environment separated from the heat sources eg:

  • operator cabins
  • maintain insulation
  • provide shade for outdoor work
Administration Training in the effects of heat on the body:

  • job rotation
  • hydration testing
  • fitness assessments
  • procedures for working in the heat
Personal Protective Equipment The use of cooling vests, uniforms made from breathable fabric. Light colours, sunscreen, sunglasses and hats for outdoor work.

(From the Canadian Centre for Occupational Health and Safety:

Symptoms of heat induced illnesses

Heat rash   –   The symptoms of heat rash include excessive sweating, resulting in the sweat gland becoming blocked and therefore reduces your ability to sweat more and lose heat.
Heat Exhaustion   –   The symptoms of heat exhaustion are headaches, dizziness, light headedness, weakness, mood changes (feeling irritable or confused), vomiting, decreased and dark coloured urine, fainting and clammy skin. If heat exhaustion is not treated, the illness may advance to heat stroke.
Heat Stroke   –   The symptoms of heat stroke are dry pale skin (no sweating), hot red coloured skin (looks like sunburn), mood changes (feeling irritable or confused), seizures, fits, collapse and unconsciousness.
All cases of heat stroke must be taken seriously as there is a high risk of death resulting from a lack of treatment. Medical attention must be sought as soon as possible. All cases of heat stroke must be treated as an emergency and the patient taken to hospital.


Our bodies are unable to acclimatize to cold in the same manner that they can adapt to heat. When the body is unable to warm itself, serious cold-related illnesses and injury may occur and permanent tissue damage and death may result. Cold related illness can slowly overcome a person who has been chilled by low temperatures, brisk winds or wet clothing. Cold stress is associated with low temperature, high air movement and humidity, for example, from a blast of cold, wet wind.

Lowering of body temperature (hypothermia) has an effect on the brain, causing erratic behaviour and numbness, muscular weakness and cramps. Hypothermia can occur when land temperatures are above freezing or water temperatures are below 37° C. Its symptoms are fatigue and drowsiness, uncontrolled shivering, cool bluish skin, slurred speech, clumsy movements, irritable, irrational or confused behaviour.

Localised exposure to cold may cause frostbite and chilblains. Frostbite occurs through freezing in deep layers of skin and tissue causing waxy-white skin, skin becomes hard and numb and usually affects the fingers, hands, toes, feet ears and nose first.
Long-term effects of working in the cold include arthritis, rheumatism, chest complaints and heart disease, because of the strain on the heart caused by circulatory changes.

All cases of cold illnesses must be taken seriously and medical attention must be sought as soon as possible. All cases of frostbite must be treated as an emergency and the patient taken to hospital.

 Controlling exposure
Identify the environment and workplace conditions that have the potential to lead to cold induced illness and injury. Employees should learn the signs and symptoms of cold-induced illnesses and what to do to the affected person.

  • Select appropriate clothing for cold, wet and windy conditions. Layer clothing to adjust to changing environmental temperatures.
  • Wear a hat and gloves in addition to underwear that will keep water away from the skin (polypropylene)
  • Take frequent short breaks in warm dry shelters to allow the body to warm up.
  • Avoid exhaustion of fatigue because energy is needed to keep muscles warm.
  • Use a buddy system (work in pairs)
  • Drink warm, sweet beverages and avoid drinking caffeine or alcohol.
  • Eat warm, high calorie foods like pasta.

 Prevention of hot/cold temperature injuries
The range of thermal comfort for workers has been found to be 19 deg C to 30 deg C. Extreme temperature can occur through a variety of different industries especially those that include working outdoors. Safety systems and procedures should be developed, communicated, implemented and reviewed. Included in this should be a formal heat/cold policy or agreement which would consider the following:


  • Induction for new workers
  • Emergency and first aid
  • PPE
  • Rest periods
  • Workplace monitoring
  • Fitness for work
  • Job rotation
  • Work rates


  • Employees self pace the rate of work task to fit the worker
    • Supervise and action changes in the workplace if adverse effects of hot and cold are identified
    • Environmental monitoring


  • Work-load
  • Acclimatisation of new/returning employees and contractors
  • Shift arrangements
  • Remove manual labour through mechanised tasks
  • Select and purchase equipment with the lowest heat emission rating
  • Isolate the hot/cold temperature source form the work environment
  • Maintain insulation

 Workers at risk of injury from extreme temperatures
– Those with predisposing health conditions such as cardiovascular disease, diabetes and hypertension.
– Those taking certain medication (check with your doctor and ask if any medicines currently being taken by yourself could affect you while working in a hot/cold environment).
– Those who are in poor physical condition, have a poor diet or are elderly.
– Outdoor workers such as construction and building workers, gardeners, etc – particularly during summer months.



Working in Heat
This publication from Safework SA provides guidance information on working in hot environments

Work environment – heat stress
Safeguard from Safework SA identifying the causes, effects and ways to deal with heat stress.

Working in the Cold
Information from the Canadian Centre for Occupational Health and Safety.

Mine safety tips (heat) –
Working in the heat –
WorkSafe Victoria