Heat stress FAQs

What is heat stress?

Working in hot conditions can be hazardous to health.

Workers who are exposed to extreme heat or work in hot environments (both indoor and outdoor) may be at risk of heat stress.

The terms ‘heat stress’ and ‘heat illness’ are general terms used to describe a range of potentially harmful medical conditions that can happen when the body is unable to cope with working in heat. These medical conditions include:

  • Heat cramps – painful cramps in muscles, caused by heavy sweating that uses up the body’s supply of salt and water.
  • Heat exhaustion – weakness, fatigue, dizziness, visual disturbance, feeling of intense thirst and heat, nausea, vomiting, palpitations, tingling and numbness of fingers and/or toes after exposure to a hot environment.
  • Heat rash (prickly heat) – an itchy rash of small raised red spots on the face, neck, back, chest and thighs caused by a hot and moist environment.
  • Heat stroke – a life threatening condition that requires immediate first aid and medical attention, caused by overexposure to heat and often with dehydration. Symptoms are dry, hot skin, high body temperature (possibly over 41°C) and may include mental confusion which can result in collapse and fitting.
  • Worsening of pre-existing illnesses and conditions.
What causes heat stress?

Heat stress occurs when the body can’t cool itself adequately via sweating.

The key things that cause heat stress are:

  • air temperature (how hot the air is around us)
  • humidity (the moisture content of the air) in the outdoor environment or workplaces, such as laundries and mines
  • amount of air movement or wind speed
  • radiant temperature of surroundings such as the sun or other sources, including furnaces, ovens and working under a metal roof
  • clothing being worn including protective clothing such as overalls, coveralls and suits worn during insecticide spraying
  • type of the physical activity being done, and the length of time it is done for
  • physical fitness of the worker (including whether a worker is used to working in a hot environment or has any pre-existing conditions – eg overweight, heart/circulatory diseases, skin diseases or use of certain medicines).
What workers are at risk of heat stress?

Workers at risk of heat stress include (but are not limited to):

  • construction workers
  • gardeners/landscapers
  • firefighters
  • bakery workers
  • farmers
  • miners
  • boiler room workers
  • kitchen and laundry workers
  • factory workers
  • shearers.
How do I know if heat stress might be a concern at my workplace?

Heat stress may be a concern in your workplace if you answer ‘yes’ to one or more of the following questions:

  • Has anyone been affected by heat in your workplace?
  • Are fans needed to keep workers cool?
  • Is work done in direct sunlight?
  • Are there heat-producing processes or equipment in the workplace? – eg in kitchens, laundries, factories, foundries.
  • Do you wear extra clothing/personal protective equipment (PPE) such as overalls, respirators or hard hats, that can make you hot?
What are the warning signs of heat stress?

Warning signs of heat stress are:

  • clammy skin
  • confusion
  • light headedness
  • fainting
  • slurred speech
  • nausea
  • fast pulse rate
  • vomiting
  • weakness
  • short temper
  • fatigue
  • loss of concentration.
How much water should I drink when working in hot conditions?

You need to drink lots of water to keep hydrated – about 200ml every 20 minutes. It is better to have frequent small drinks of cooled water rather than infrequent large drinks.

Should I drink energy drinks, soft drinks and coffee instead of water when working in hot conditions?

No.

Coffee and energy drinks cause increased urine output and can make working in the heat more dangerous by causing you to dehydrate more quickly.

You should also not rely solely on soft drinks or caffeinated drinks.

Alcohol should definitely be avoided when working in the heat because it also causes increased urine output – eg if you drink one can of beer, you will lose more than that amount of urine.

The safest thing is to stick to drinking water.

How do I know if I am getting dehydrated?

When becoming dehydrated, you are likely to experience, in order of increasing dehydration:

  • mild to severe thirst
  • dry lips and tongue
  • a decrease in the amount of urine passed, and it will appear darker than normal
  • faster breathing and faster heart rate than normal
  • weakness or light-headness (particularly when standing)
  • dry, wrinkly-looking skin with loss of skin elasticity
  • sunken eyes (in severe cases).
Are some people more likely to suffer from heat stress?

Yes.

People are at greater risk of the effects of heat stress if they:

  • are overweight
  • are physically unfit
  • are pregnant
  • have consumed alcohol
  • are over 65 years old
  • suffer from heart diseases
  • take certain medications
  • are not used to working in the heat.
What are heat-related injuries?

Apart from heat stress, hot working conditions may either contribute to or cause other health and safety problems. For example:

  • loss of grip while handling tools, objects and controls due to sweaty hands
  • slips, trips and falls due to dizziness, fainting or fatigue
  • errors/mistakes or clumsiness due to fogged up safety glasses or heat fatigue
  • not following safe work procedures or cutting corners due to fatigue and/or discomfort
  • not using PPE due to discomfort
  • burns from contact with hot surfaces or substances
How often should rests be taken when working in heat?

Regular rest breaks in a cooler or shaded area should be taken every hour, if possible, to help your body cool off, especially where the work is hard, physical work.

The length of the break should be increased if the temperature is very high.

Is there a maximum temperature at which workers should stop?

The Work Health and Safety (WHS) Regulation 2011 requires your employer to ensure, so far as is reasonably practicable, that:

  • workers working in extremes of heat or cold are able to carry out their work without risk to their health and safety

The WHS legislation does not state a precise temperature at which workers should stop work. This is because the effects of exposure to heat depend on a number of factors – not just the temperature. These other factors include:

  • air temperature (how hot the air around us is)
  • humidity (the moisture content of the air)
  • amount of air movement or wind speed
  • radiant temperature of surroundings either from the sun or other sources including furnaces, ovens and working under a metal roof
  • clothing being worn including protective clothing such as overalls, coveralls and suits worn during insecticide spraying
  • type of the physical activity being done and the length of time it is done for
  • physical fitness of the worker, including whether a worker is used to working in a hot environment or has any pre-existing conditions - eg overweight, heart/circulatory diseases, skin diseases or use of certain medicines.
How can heat stress be prevented in indoor work environments?

Using just one control is unlikely to be effective to manage the risks associated with working in hot environments, so a number of controls might need to be used together to get the best results.

Measures to prevent or reduce the risk of heat stress include:

  • designing buildings to incorporate good air flow where hot process are located – eg via windows, shutters or roof design (to encourage ‘chimney effects’ to help dissipate the heat from the structure)
  • installing reflective or light-coloured external wall cladding and roofing
  • locating workers in air conditioned control rooms away from the hot work
  • increasing air movement using fans
  • installing shields or barriers to reduce radiant heat from sources such as furnaces
  • removing heated air or steam from hot processes using local exhaust ventilation
  • installing air conditioners to reduce air temperature
  • insulating/enclosing hot processes or plant
  • using chiller units, in extreme cases, to relieve air temperature and humidity – eg when working in enclosed roof spaces
  • placing reflective shields or coatings on radiant heat spots
  • insulating hot surfaces
  • providing mechanical equipment to reduce the need for strenuous physical work
  • installing blinds or curtains on windows to reduce direct sunlight
  • providing easy access to cool drinking water
  • Drinking enough water to maintain adequate fluid replacement. Regular meals and snacks will replace salt and electrolytes lost through sweating
  • ensuring workers are used to working in the heat and not taking medication that will weaken their ability to cope with heat stress
  • providing regular breaks away from hot processes in a clean, cool, well-ventilated area – air conditioned where possible
  • implementing a ‘buddy system’ where each worker looks after the other and ensures that their buddies are drinking water, taking breaks and not showing signs of heat stress
  • ensuring work is paced to meet the conditions
  • increasing worker rotation
  • sharing unavoidable heavier jobs between more workers.

Training should be provided and include:

  • working safely in the heat
  • the types of work that increase the risk of heat stress
  • how to identify if you, your buddy or your workmates have symptoms of heat stress, and
  • how to report it immediately.

PPE should be provided and should be:

  • comfortable to wear
  • made of suitable materia
  • ldesigned to provide protection while keeping you cool in hot conditions
  • task-specific, for example:
    • indoor workers exposed to humid heat (– eg in kitchens, laundries) should wear loose fitting, lightweight clothing for air movement
    • indoor workers exposed to radiant heat should be supplied with reflective aprons and face shields
    • foundry workers can be provided with a jacket of leather or suitably flame resistant material. High-visibility colour options can also assist with visibility in these workplaces.
How can outdoor workers be protected from heat stress and UV radiation exposure?

A range of controls should be considered when working outdoors in the heat because no one control will be completely effective.

Measures to prevent or reduce the risk of heat stress include:

  • where possible, relocating outdoor work so it is done out of sun in a covered, well ventilated building/structure that is not exposed to radiant heat sources – eg large exposed outdoor cemented areas; metal or light-coloured walls
  • where possible, starting work on the shady side of the building, and following the shade around the building as the day progresses
  • providing mechanical equipment to reduce the need for strenuous physical work
  • placing reflective shields and barriers to reduce radiant heat spots – eg in unshaded outdoor cement areas; generators and other large powered equipment that may be being used during outdoor work
  • providing screens, umbrellas, canopies or awnings over sections of the site to create shade where work is being carried out
  • providing easy access to cool drinking water
  • planning work routines so outdoor work tasks are done:
    • early in the morning or later in the afternoon when the levels of ultra-violet radiation (UVR) from the sun are lower
    • indoors or in shaded areas during the middle of the day when the levels of UVR from the sun are strongest
    • based on the ultra-violet (UV) alert issued by the Bureau of Meteorology available via their SunSmart App for iPhone and Android at bom.gov. au
  • sharing outdoor tasks and rotating staff so the same person is not always out in the sun
  • ensuring workers are used to working in hot conditions and not taking medication that will weaken their ability to cope with heat stress
  • providing regular breaks away from the sun in a clean, cool, well-ventilated (air conditioned where possible) area – eg shed or vehicle
  • implementing a ‘buddy system’ where each worker looks after the other and ensures that their buddies are drinking water, taking breaks and not showing signs of heat stress
  • ensuring work is paced to meet the conditions
  • increasing worker rotation
  • sharing unavoidable heavier jobs between more workers
  • keeping people away from hot processes
  • allowing workers to gradually get used to working in a hot environment.
  • Training should be provided and include:
    • working safely in the heat
    • the types of work that increase the risk of heat stress
    • how to identify if you, your buddy or your workmates have symptoms of heat stress, and
    • how to report it immediately.

PPE should be provided and should be:

  • comfortable to wear
  • made of suitable material
  • task-specific
  • esigned to provide sun protection while keeping you cool in hot condition
  • sultraviolet protection factor (UPF) 50+ rated long-sleeved collared shirts and long pants
  • a suitable hat
  • SPF 30+ sunscreen, and
  • appropriate sunglasses.

Outdoor work should be planned ahead to ensure all necessary measures for preventing heat stress can be implemented when hot weather is predicted.

If you work outdoors and your workplace does not offer any sun protection measures, raise the issue with your health and safety representative or manager.

What if there is no shade where I am working?

UV levels are highest between 10am and 2pm (or 11am and 3pm during daylight saving) so the best thing to do during the hot months and these times is to work indoors or in the shade.

Whenever it is reasonably practicable to do so:

  • reschedule work to cooler times of the day, or at a different location if this is practicable
  • reschedule outdoor work tasks, especially those where no shade is available, for early in the morning or later in the afternoon when UV levels are lower
  • provide screens, umbrellas, canopies or awnings over sections of the site to create shade for work areas and for taking breaks, to shield workers from the UV rays of the sun, as well as from the direct heat of the sun
  • share outdoor tasks and rotate staff so the same person is not always out in the sun.
What clothing should be worn when working in the sun?

When working in the sun, clothing made of lightweight, closely woven material with a UPF 50+ rating should be worn.

The clothing should be long pants and work shirts with a collar and long sleeves should be worn to cover as much skin as possible.

The clothing needs to balance three important workplace needs:

  • sun protection
  • staying cool in hot conditions, and
  • safety.

It is also very important that the clothing design does not create a secondary hazard – eg loose clothing can be caught in machinery.

What is the best type of hat to wear when working in the sun?

The most important thing is that the hat shades the face, ears and neck from the sun.broad brimmed styled hats should have a minimum 7.5cm brimbucket style hats should have a deep crown, angled brim of minimum 6cm and sit low on the headcaps/legionnaire style hats should have a flap that covers the neck and joins to the sides of the front peak. If wearing a hard hat or helmet, it should have a brim attachment or a legionnaire cover.

What type of sunglasses are recommended for working in the sun?

Eyes can be permanently damaged by the sun’s UV radiation, so it is preferable that sunglasses:

  • be close fitting, wraparound style
  • meet the Australian Standard (AS/NZS1067: 2003 – category 2, 3 or 4 ) and are safe for driving (this information is contained on the swing tag when purchased)
  • have an eye protection factor (EPF) 10. Safety glasses that meet AS/NZS1337 still provide sun protection
  • have polarised lenses to reduce glare and make it easier to see on sunny days.

The darkness of the lens should not be used to gauge protection from UVR. Some clear lenses may provide maximum protection from UVR, although a tint is desirable to reduce glare.

It is important to note that the price of sunglasses does not have any relationship to protection from UVR. Low cost sunglasses that comply with the sunglass standard may also provide excellent protection fron UVR.

What sunscreen is recommended for working outdoors?

It is important to remember that no sunscreen provides complete protection from UV radiation – so never rely on sunscreen alone.

The NSW Cancer Council recommends that sunscreens should:

  • be at least SPF30+, broad spectrum and water resistant
  • be applied generously to clean, dry skin 15 to 20 minutes before going outdoors
  • reapplied every two hours or more often when sweating.

Always check and follow the use by date on sunscreen.

It is also recommended to protect lips with an SPF 30+ lip balm.

What should I do if a co-worker is suffering from heat stress?
What should I do if I think my workplace temperature is too high?

If you are concerned that you are working in an unsafe and hot environment, you should alert your immediate supervisor to the problem and discuss some of the possible ways of reducing the impact on you and your co-workers.

If the supervisor will not deal with the problem or you believe the problem hasn’t been fixed, you should contact your Health and Safety Representative (HSR) if there is one, or the supervisor’s manager.

If the matter is still unresolved and you continue to believe that an unsafe situation exists, you should contact SafeWork on 13 10 50 for further advice.

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