Working in extreme heat: the facts
Workers exposed to extreme heat or work in hot environments (indoor or outdoor) may be at risk of heat stress.
The human body gets rid of excess heat by sweating, so any factor that reduces the effectiveness of sweating makes it harder to for the body to regulate its temperature. Heat-related illness happens when the body can’t cool itself down by sweating.
Exposure to heat depends on a number of factors – not just temperature alone.
In addition to the air temperature (how hot the air is around you), these factors include:
- humidity – the moisture content of the air (as humidity increases, the air is less able to absorb moisture from the skin and sweating becomes less effective at cooling the body)
- amount of air movement (indoors) or wind speed (outdoors)
- radiant temperature of surroundings, such as the sun (outdoors) or furnaces, ovens and working under a metal roof (indoors)
- clothing being worn – including personal clothing being worn under protective clothing such as overalls
- type of physical activity being done and the length of time it is done for
- age and physical fitness of the worker
People are at greater risk of the effects of heat-related illness if they:
- are overweight
- are physically unfit
- are pregnant
- have consumed drugs or alcohol
- are over 45 years old (research suggests workers over 45 years of age experience a lower ability to work in a hot environment, which can make them a particularly vulnerable group as heat intensifies)
- suffer from heart or lung disease
- take certain medications or are on a fluid-restricted diet
- aren’t used to working in the heat.
Research also indicates younger workers can be more susceptible to heat-related illness – the possible reasons being physically strenuous tasks combined with a lack of skills or experience and a reluctance to raise problems with supervisors.
Common occupations that could expose workers to heat-related illness include (but aren’t limited to):
Fire fighters and other emergency workers (eg: air ambulance; etc)
Farmers, agricultural workers
External house painters
Kitchen and laundry workers
Boiler room workers
Work in confined spaces, including ceiling and roof cavities
Some factory workers
The common factors in these high-risk industries are the combination of hard physical work and being exposed to hot (and/or humid) environments, either outdoors in the sun or in indoor confined hot spaces.
Between 2001 – 2013 in Australia, 13 workers died from working in extreme environmental heat. All of these people except one (who was working in an enclosed ceiling space) died from exposure to outdoor heat.
Themes that emerged in the relevant coronial inquiries included:
- in cases of workers with colleagues nearby, there was a failure to recognise the signs of heat-related illness
- in cases of workers working alone, they either failed to recognise or to act on their symptoms, or were unable to call for help
- a lack of co-ordination between the parties responsible for workers’ safety
- the need for systems to identify when a worker is suffering heat-related illness (and allow them to seek assistance if isolated)
- the need to schedule work to avoid the hottest times of the day or season of the year
Heat-related illness might be a problem in your workplace if you answer ‘yes’ to one or more of the following questions:
- Has anyone ever been affected by heat in your workplace?
- Is work done in direct sunlight?
- Are there heat-producing processes or equipment in the workplace? – eg in kitchens, laundries, factories, foundries.
- Do workers wear extra clothing/personal protective equipment (PPE) such as overalls, aprons or respirators that can make you hot?
It is more difficult to control the environment outdoors, than it is indoors. Prolonged periods of extreme hot weather can make existing controls less effective (eg: workers may be able to be diverted to other tasks for one or two extremely hot days, but the PCBU may not have the resources to postpone work for a prolonged period of extreme heat).
Recent climate data shows that extreme heat events are occurring in Australia more often and for longer periods and this is expected to continue with greater intensity in the future. There are also increasing extremes of temperature, which has seen Australia experiencing more warm weather and extreme heat, and fewer cool extremes.
This means that workers are now exposed to hotter working environments for longer periods and these more frequent, longer heatwaves may introduce new hazards as well as affect the control options available.
If work has to be done outdoors - in extreme heat, then the PCBU must take steps to manage risks to protect workers.
Identify the amount of heavy physical work that will be required and then ensure all necessary measures to prevent exposure to UV radiation and heat-related illness are implemented.
Hierarchy of controls
PCBUs must focus on the hierarchy of controls when managing risks. Usually, a combination of controls are needed to get the best results. These include:
- planned work routines to avoid working in the middle of the day, eg: outdoor work tasks are done early in the morning and later in the afternoon when the levels of ultra-violet radiation (UVR) from the sun, as well as hopefully the temperature, are lower,
- an air-conditioned site shed
- canopies or awnings over the section of the site where work is currently being done
- mechanical aids to reduce the need for physical exertion
- an effective ‘buddy system’ is in place, where workers check each other frequently to ensure they are regularly drinking enough water, taking breaks and not showing signs of heat-related illness. (Apps may assist with monitoring worker’s physical symptoms – and may even be able to assess possible deteriorating mental states).
- easy access to cool water - located near each work area to encourage frequent drinking
- access to crushed ice (to ingest and for use as ice towel)
- cooling vests
- regular rest breaks - particularly when the work is very physical. The frequency and length of the break should be increased if the conditions become hotter and/or more humid - up to 30 minutes break every hour, in a cooler area, to help the body cool off.
- arrange for more workers to do the job
- pace the work to meet the conditions. Where possible, allow workers to self-pace (set their work rate so they are comfortable)
- reduce the length of shifts
Everyone needs to drink more water when working in a hot environment – whether it’s indoors or outdoors and regardless of how active we are.
Don’t wait until you’re thirsty – it’s much better to have frequent smaller drinks of cooled water rather than infrequent large drinks. On hot days, you should drink a small cup (200ml) of cool water every 15 to 20 minutes.
Remember - cool water, not extremely cold, because it can cause stomach cramps.
Workers with medical conditions (eg: on limited fluid intake, taking prescribed fluid or salt pills) must check with their doctor before commencing work in extreme heat.
Energy drinks, coffee and some soft drinks can increase urine output. These types of drinks can dehydrate you more quickly and make working in the heat even more dangerous.
Alcohol should definitely be avoided when working in the heat because it also causes increased urine output.
The safest thing is to stick to drinking water.
Warning signs of heat-related illness are:
- feeling hot, weak and fatigued, with clammy skin
- loss of concentration, poor judgement, irritability
- clumsiness, slower reaction times
- slurred speech
- intense thirst, also nausea and vomiting
- rapid breathing and shortness of breath
- fast, weak pulse rate; palpitations
- tingling, numbness of fingers and/or toes
- visual disturbance
- dizziness, fainting (particularly when standing)
- seizures and unconsciousness (in extreme cases)
A normal body temperature ranges between 36.5 and 37.4°C, but temperature readings vary, depending on where it is measured.
- Core body temperature refers to the temperature of the body’s internal organs, such as the heart, liver, brain and blood.
- Accurate measurement of core body temperature involves invasive medical procedures in hospital so it is a person’s peripheral body temperature (their ‘skin level’ temperature) that is commonly measured in non-invasive sites such as the mouth, ear, armpit and (less frequently) rectum because these areas are easily accessible and are believed to provide the best estimation of the core body temperature.
- Despite this, there can be as much as 1 – 2 degrees difference between the actual core body temperature and a peripheral temperature measurement. The armpit temperature tends to be the least accurate because there are no main blood vessels in the armpit area.
- Digital electronic oral and ear thermometers have largely replaced glass mercury thermometers as the instruments of choice for measuring temperature.
- Factors that can affect the accuracy of peripheral body temperature measurements include:
- Mouth - recent ingestion of food or fluid, smoking and having a respiratory rate >18 per minute
- Ear - build-up of ear wax
- Armpit - environmental temperature and perspiration
When becoming dehydrated, you are likely to experience (in order of increasing dehydration):
- mild to severe thirst
- dry lips and tongue
- decreased amount of urine passed that appears darker than normal
- increased breathing and heart rate
- weakness or light-headedness (particularly when standing)
- dry, wrinkly-looking skin with loss of skin elasticity
- sunken eyes (in severe cases).
If you experience any of these symptoms, you need to immediately:
- move to a cool place that has circulating air, such as a site shed (air-conditioned where possible) or even the cabin of a vehicle
- loosen all tight clothing and remove unnecessary garments, including PPE (mask, apron, overalls, etc)
- drink frequent, small amounts of cool (not cold) water
- seek medical advice if your symptoms don’t improve.
The problem is once a person is past the dehydration stage, their ability to self-assess will be affected from symptoms such as:
- loss of concentration
- poor judgement
- dizziness and fainting
Themes that emerged from the coronial inquiries into the 13 work-related fatalities from heat-related illness that occurred between 2001 – 2013 in Australia (noting that 12 of these deaths resulted from working outdoors) included:
- in cases of workers with colleagues nearby, there was a failure to recognise the signs of heat-related illness
- workers working alone either failed to recognise or to act on their symptoms or were unable to call for help
- the need for systems to identify when a worker is suffering heat-related illness and allow them to seek assistance if isolated.
What can be done?
Working in heat and exposure to UV radiation are known hazards for workers.
PCBUs must know when their workers are at risk of both sun and heat exposure and have systems in place to reduce the risks – focusing on the hierarchy of controls – so that all workers:
- can identify the signs of heat-related illness
- know how to – and the importance of – observing / monitoring their co-workers
- know what to do if a co-worker seems affected
- know what immediate first aid to give to an affected worker, and when to call for further medical assistance
More information can be found in Recognising and treating heat-related illness at work and Protecting your workers from extreme heat.
There are a number of things workers can do to guard themselves against getting heat-related illness. They should:
- commence work well hydrated to provide a buffer against the development of dehydration
- eat regular meals and snacks to help replace salt and electrolytes lost through sweating
- drink enough water while working to maintain adequate fluid replacement – at least a small cup (200ml) of cool (not cold) water every 15-20 minutes
- never replace water with energy or caffeinated drinks – especially in hot weather
- never drink alcohol or take drugs prior to, or at, work
- never come to work in a hot environment with a hangover
- do not take salt tablets (because the body needs more water to help it get rid of the salt – which will increase the risk of dehydration, as well as the risk of high blood pressure)
- always use the mechanical aids provided (eg: fans, cooling units, trolleys, etc)
- take their rest breaks in air conditioned areas (eg: site shed, vehicle cabin) or at the very minimum, in a shaded area, remove any unnecessary PPE (eg: aprons, gloves) and if necessary, ingest crushed ice and/or apply ice towels.
In hot and humid work environments with temperatures in the 300s, whether indoors or outdoors, regular rest breaks should be taken about every hour in a cooler (air conditioned where practicable) or shaded area to help your body cool off – especially when you’re doing hard, physical work. Make sure to drink some cool (not cold) water while on your break and, if necessary, ingest crushed ice and/or apply ice towels.
The frequency and length of the break should be increased if the conditions become hotter and/or more humid - particularly when the work is very physical. The frequency and length of the breaks should be increased if the conditions become hotter and/more humid - up to 30 minutes break every hour, in a cooler area, to help the body cool off.
PCBUs can check the daily UV levels by:
- the daily newspaper
- the Bureau of Meteorology website
- the Bureau of Meteorology and Cancer Council Australia SunSmart smart phone apps
When UV levels are 3 and above, they’re strong enough to damage the skin and eyes – and sun protection must be provided and used.
On a construction site, the site manager/supervisor and sub-contractor should review their outdoor work schedules, including when the UVR peaks, to assist in developing appropriate sun protection measures. They also need to ensure the agreed protection measures are implemented.
If it is reasonably practicable to do so:
- reschedule work to cooler times of the day, or at a different location
- schedule 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
- rotate staff so the same people are not always out in the sun
- provide regular breaks away from the sun in a clean, cool, well-ventilated (air conditioned where possible) area – eg shed or vehicle.
When working in the sun, work clothing needs to be made of lightweight, closely woven material with a UPF 50+ rating. You should wear long pants and work shirts with a collar and long sleeves to cover as much skin as possible.
The clothing needs to balance three important workplace needs:
- sun protection
- staying cool in hot conditions, and
It’s also very important that the clothing design doesn’t create a secondary hazard – eg loose clothing can be caught in machinery.
The most important thing is for the hat to shade your face, ears and neck from the sun.
Recommended hats are:
- broad brimmed styled hats (minimum 7.5cm brim)
- bucket style hats with a deep crown, angled brim (minimum 6cm width) and sit low on the head
- caps / legionnaire style hats with a flap that covers the neck and joins to the sides of the front peak.
If wearing a hard hat or helmet, make sure you have a brim attachment or a legionnaire cover.
Eyes can be permanently damaged by the sun’s UV radiation, so it is preferable that sunglasses:
- are a 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.
- have polarised lenses to reduce glare and make it easier to see on glarey days.
- The darkness of the lens shouldn’t be used to gauge protection from UVR. Some clear lenses may provide maximum protection from UVR, although a tint is desirable to reduce glare.
- The price of sunglasses doesn’t have any relationship to protection from UVR. Low cost sunglasses that comply with the sunglass standard can provide excellent protection from UVR.
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
- be reapplied every two hours – and it should be applied more often when you’re sweating.
Always check and follow the use by date on sunscreen.
It is also recommended to protect your lips with an SPF 30+ lip balm.
If you are concerned that you are working in an unsafe 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 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 NSW on 13 10 50 for further advice.
Apart from heat-related illness, working in a hot environment also contributes to, or can cause, other health and safety injuries because of a worker being possibly fatigued, physically weak, having slower reaction times and poor judgement.
Heat-related injuries can be quite common – particularly in tasks that require attention, coordination and immediate memory skills.
Examples of heat-related injuries include:
Lacerations from loss of grip while handling tools, objects and controls
Slip / trip / fall