Working safely in hot conditions

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Heat stress may affect people in all parts of Western Australia during our summer months and may affect workers at some workplaces throughout the year. The effects of heat stress range from discomfort to life threatening illnesses such as heat stroke.

Read more on how to avoid heat illness when working in hot conditions.

Hot workplaces are common in Western Australia. Heat may result from:

  • hot climatic conditions
  • heavy work in moderately hot conditions
  • hot work processes (such as welding or working in foundries)
  • radiant heat from the environment and surroundings
  • work where heavy protective clothing must be worn or
  • any combination of these factors.

The Work Health and Safety Act 2020 requires the employer or person conducting a business or undertaking (PCBU) to provide and maintain a working environment in which workers are not exposed to hazards or risks to their health and safety. This applies to any risk to safety and health, including illness from working in heat conditions.

What is heat stress?

Heat stress is the total heat burden to which the body is subjected by both external and internal factors. Heat stress causes increased blood flow to the skin, which allows the release of heat. When physical work is performed, blood is diverted to the muscles resulting in a lower release of heat through the skin.

The body must therefore balance the heat transferred into the body, the heat generated in the body and the heat coming out of the body.

Heat illness

If the body can’t balance its heat inputs, heat stress may lead to heat illness (or heat strain), a physical response designed to reduce body temperature.

Types of heat illness include:

  • discomfort - flushed skin, increased sweating, heat rashes (prickly heat)
  • mild heat illness - feeling tired, weak or dizzy, cramps, reduced work capacity, reduced attention span, irritability
  • heat exhaustion - fainting, headache, low blood pressure, nausea, clammy, pale or flushed skin, normal to high body temperature of up to 39°C
  • heat stroke - irritability, confusion, speech problems, hot dry skin, convulsions, unconsciousness, body temperature above 40°C, cardiac arrest - potentially fatal, a life threatening condition that requires immediate first aid and medical attention.

Are some people more prone to heat illness than others?

Some people are less tolerant of heat than others and working in hot conditions may aggravate their pre-existing illnesses and conditions. People who are at greater risk of heat illness and should heed medical advice are those who:

  • are medically unfit
  • are on certain medications
  • overweight
  • have heart disease
  • are pregnant
  • abuse alcohol
  • are not acclimatised to the hot conditions.

Acclimatisation can take 7-14 days to take effect and can be reduced after 3 days away from hot work. Acclimatisation is entirely lost after 4 weeks away from hot work and so medical advice should always be followed.

Managing the risk of heat illness

In identifying, assessing and controlling risks associated with heat illness, employers should consult with workers likely to be exposed to heat as well as with any elected health and safety representatives.

Identifying risk factors

The key risk factors to consider are:

  • air temperature
  • humidity (high humidity limits the evaporation of sweat which is a key cooling mechanism for the body)
  • radiant heat from the sun or other sources such as furnaces, ovens and hot vessels
  • air movement or wind speed
  • workload – the intensity and duration of the work
  • physical fitness of the worker including acclimatisation and any pre-existing conditions such as obesity, heart/circulatory diseases, skin diseases or use of certain medicines that affect the body’s ability to manage heat (e.g. diuretics, antidepressants and anticholinergics
  • clothing (including protective clothing that may restrict air flow across the skin and hinder evaporation of sweat).

Assessing the risk of heat illness

The risk assessment should be carried out by a person competent in heat assessment and may include use of an appropriate heat stress index. A commonly used and recognised index is the Wet Bulb Globe Temperature (WBGT) which takes into account air temperature, radiant heat, humidity and air movement and adjustments such as physical workload, clothing and the work organisation.

The Thermal Work Limit (TWL) is an alternative approach being used increasingly in Australian workplaces, particularly in the resource industry. It accounts for all of the major factors mentioned above and provides guidance on managing workloads and fluid intake.

If the assessment indicates a risk of heat illness occurring, PCBUs need to put control measures in place. Workers considered more at risk due to factors such as pre-existing medical conditions should be medically assessed.

Where the employer has implemented practical controls, but is unsure as to whether there is a still a health risk, various forms of risk assessment tools can be utilised:

Some of these assessments require information such as the WBGT.

This should preferably be measured in the work area, however as a guide, the Bureau of Meteorology provides WBGT values for major centres and occupational hygienist can also assist with such assessments.

In some cases, such as when full impermeable suits are worn, direct physiological monitoring of each worker may be required to monitor heat stress.

Reducing the risk of heat stress

There is a recommended order of control measures that eliminate or reduce the risks of injury or harm and often a combination of controls will be necessary.  

Engineering

Engineering controls are an effective way of reducing heat stress and preventing or minimising occurrence of heat illness. Examples include:

  • increasing air movement using fans
  • installing shade cloth to reduce radiant heat from the sun
  • installing shields or barriers to reduce radiant heat from sources such as furnaces or hot vessels
  • removing heated air or steam from hot processes using local exhaust ventilation
  • installing air conditioners or coolers to reduce air temperature
  • locating hot processes away from people and
  • insulating /enclosing hot processes or plant.

Organisation of work

 

Reducing heat stress requires careful work organisation, such as:

  • rescheduling work so that hot tasks are performed during the cooler part of the day or in the cooler times of the year
  • reducing the time an individual spends doing the hot tasks, e.g. by job or task rotation
  • arranging for more workers to do the job
  • providing additional rest breaks in cool, shaded areas and
  • using mechanical aids to reduce physical exertion.

Providing training and information

Training and information will enable workers to:

  • identify hazards associated with heat stress
  • recognise symptoms of heat stress and heat illness
  • identify appropriate first aid procedures
  • understand how to avoid heat illness
  • recognise the potential dangers associated with the use of alcohol and/or drugs and
  • use appropriate protective clothing and equipment.

Toolbox and pre-start meetings are key to reinforcing actions that prevent heat illness.

Providing personal protective clothing

Providing PPE such as reflective aprons and face shields can reduce exposure to radiant heat. Ice vests and liquid and air circulating systems can be worn under PPE where appropriate.

Outdoor workers should be provided with protection against ultraviolet exposure such as a wide brim hat, loose fitting, long sleeved collared shirt and long pants, sunglasses and sunscreen.

Preventing heat illness

There are many ways heat illness can be prevented in your workplace:

  • replace lost fluids - encourage drinking 250 ml of water every 15 to 20 minutes during hot work conditions. Regulation r. 41A of the Work Health and Safety (General) Regulations 2022 requires that a supply of clean, cool drinking water is provided and readily accessible to workers. Workers should be encouraged to start their shift fully hydrated. Keeping well hydrated is a critical factor in avoiding heat illness which should be reiterated to your workers during workplace inductions.
  • limit caffeine, carbonated drinks, alcohol and tobacco use
  • have rest breaks in a cool place
  • do not take salt tablets unless specifically advised by your doctor
  • inform your PCBU if you have an underlying health condition that may increase your risk of heat illness
  • maintain a healthy diet with regular exercise
  • wear cool clothing, a wide brimmed hat and use sunscreen
  • take a break and tell your manager if you are feeling tired, dizzy or weak or having trouble concentrating.

Although water is generally adequate for fluid replacement, low joule cordials and electrolyte replacement solutions may be provided to encourage fluid intake. High sugar cordials and sports drinks are not recommended.

Allowing for acclimatisation

Workers, in particular those with fly-in fly-out (FIFO) contracts may experience significant differences in climatic conditions between the workplace and their off-work location, especially after an extended absence.

Suitable acclimatisation procedures should be considered for workers who are subject to hot work conditions. These procedures should be developed in consultation with workers and consider the particular shift roster schedules used.

Other preventative measures

Other controls to eliminate or reduce heat stress include providing:

  • adequate supervision of workers
  • first aid facilities, instruction and training and access to medical help.

Employers should plan ahead and ensure that all the necessary measures for preventing heat illness can be implemented when hot weather is predicted.

How should heat illness be treated?

When one of your workers is experiencing heat illness:

  • ensure the person rests in the coolest available area and drinks cool, but not cold fluids
  • provide an electrolyte supplement or sports drink if available.

If the symptoms do not reduce quickly or if symptoms of heat stroke are present, contact a doctor, nurse, ambulance service or first aid officer for assistance.

Heat exhaustion

Symptoms of heat exhaustion can include:

  • fainting
  • headache
  • low blood pressure
  • nausea
  • clammy
  • pale or flushed skin
  • normal to high body temperature (up to 39°C).

To treat heat exhaustion:

  • move your worker to a cooler environment with good air movement
  • loosen their clothing and if necessary remove unnecessary clothing
  • provide cool, but not cold fluid, for them to drink if they are conscious
  • sponge them with cold or iced water
  • seek medical attention if the person does not recover quickly or vomits.

Heat stroke

Symptoms of heat stroke can include:

  • irritability
  • confusion
  • speech problems
  • hot dry skin
  • convulsions
  • unconsciousness
  • body temperature above 40°C
  • cardiac arrest - potentially fatal
  • a life threatening condition that requires immediate first aid and medical attention.

To treat heat stroke:

  • follow the DRSABCD action plan
  • immerse the person in a bath of cold/iced water. If immersion is not practical, dip towels in iced water and place them on the person
  • apply cold packs/wrapped icepacks to the neck, groin and armpit areas
  • call 000 for an ambulance
  • provide water to drink if the person is fully conscious and able to swallow
  • seek urgent medical attention if the person becomes unconscious or has a seizure.

Make the job safe - talk about health and safety at work

If you believe there are problems with heat stress at your workplace you should discuss them with your employer and your health and safety representative.

Other sources of information 

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