Heat-related illness

‘Heat-related illness’ is a term that describes a range of progressive heat-related conditions.

The human body needs to maintain a body temperature of approximately 370C.

If the body has to work too hard to keep cool, it starts to overheat and a worker begins to suffer from heat-related illness.

Heat-related illness is a newer term that replaces the term ‘heat stress’.

It is used to describe a range of progressive heat related conditions, including:

  • dehydration
  • heatstroke
  • fainting
  • heat rash
  • heat cramps
  • heat exhaustion

There were 13 work-related fatalities from working in extreme heat in Australia between 2001 – 2013.

Twelve of these workers died from exposure resulting from working outdoors. The 13th worker died after working in an enclosed ceiling space during a heatwave.

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.

Identifying heat-related illness

Heat-related illness has warning signs

Warning signs of heat-related illness are:

  • feeling hot, weak and fatigued
  • clammy skin
  • headache
  • loss of concentration, poor judgement, irritability
  • confusion
  • clumsiness, slower reaction times
  • slurred speech
  • intense thirst
  • 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)

If a worker experiences any of these symptoms, they need to immediately:

  • be moved to a cool place that has circulating air
  • have all tight clothing loosened and unnecessary garments removed, including PPE
  • drink frequent, small amounts of cool (not cold) water
  • seek immediate medical advice if their symptoms don’t improve.
Dehydration - the symptoms and what to do about it

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
  • drink frequent, small amounts of cool (not cold) water
  • seek medical advice if your symptoms don’t improve.

Note on hydration

When working in heat, dehydration is a major risk, so workers must stay hydrated. Dark or reduced urine output can indicate dehydration, so ensure your workers know to observe their urine output when working in extreme heat. The NSW Health Urine Colour Chart can help workers determine if they are becoming dehydrated.

Some people are at greater risk of suffering from heat-related illness than others

How hot individual workers feel will be different in every situation. It depends on the individual worker, the work they are doing, the clothing and PPE they are wearing and the environment in which they are working.

Some workers are more susceptible to heat-related illness, eg if they:

  • have suffered it previously
  • are overweight or obese
  • are physically unfit
  • are pregnant
  • have recently consumed drugs or alcohol
  • are not acclimatised to working in the hot environment
  • suffer from heart or lung disease, or
  • take certain medications or are on a fluid-restricted diet – both of which can affect how they can be treated

In addition, research suggests that:

  • workers over 55 years of age experience a lower ability to work in a hot environment
  • younger workers (aged 25 or less) can be more susceptible to heat-related illness

PCBUs must have suitable systems in place to ensure any resulting medically-ordered work restrictions can be accommodated, so far as is reasonably practicable.

Usually, a person doesn’t realise they may be suffering from heat-related illness

The problem is that once a person is past the dehydration stage, their ability to self-assess will be affected from the symptoms they could be experiencing, such as:

  • confusion
  • fatigue
  • 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 in Australia between 2001 – 2013 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.

Heat-related illness exposure incidents can be under-reported because they are often attributed to other causes.

Symptoms like dizziness, headache, nausea, weakness, unsteady pace, irritability, disorientation and being very flushed – which are early signs of heat-related illness – are often blamed on other conditions.

Preventing heat-related illness when at work

There are a number of things workers can do to guard themselves against getting heat-related illness when working in a hot environment.

PCBUs should provide suitable training and instruction to workers so they (including those who are from culturally and linguistically diverse [CALD] backgrounds) understand to:

  • commence work well hydrated, and fit for work
  • consult with the PCBU regarding workplace heat management and monitoring
  • 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, caffeinated drinks or alcohol
  • always use the mechanical aids provided (eg fans, cooling units, trolleys, etc)
  • take their rest breaks in air conditioned areas or at the very minimum, in a shaded area
  • remove any unnecessary PPE – only if safe to do so.
  • If necessary, ingest crushed ice and/or apply ice towels

Drinking enough water is vital 

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. Fresh water is the recommended fluid to drink in hot environments because it’s best for hydrating the body.

PCBUs must provide clean drinking water for workers that is free of charge, located near each work area and available to drink at all times (not just during breaks).

It’s important to know that drinking satisfies your thirst first, before it will start to replace any fluid loss. So, 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 at least a small cup (200ml) of cool water every 15 to 20 minutes.

If water supplied for certain industrial processes or for fire protection is not suitable for drinking, ensure these water supply points are marked with signs warning that the water is unfit for drinking.

Don’t replace drinking water with energy drinks, soft drinks or coffee - which can increase urine output and dehydrate you much more quickly. This can make working in the heat – whether indoors or outdoors – even more dangerous. Alcohol should be avoided when working in the heat because it also causes increased urine output.

Temperature is just one of many factors to consider 

The WHS Regulation 2017 (the WHS Reg) requires employers and other PCBUs  to ensure, so far as is reasonably practicable, that workers working in extremes of heat can carry out their work without risk to their health and safety.

The WHS Reg does not state a precise temperature at which workers should stop work because exposure to heat-related illness depends on a number of factors.

In addition to the air temperature, other essential environmental factors are the:

  • humidity
  • amount of air movement
  • radiant temperature of surroundings either from the sun or from furnaces, ovens and working under a metal roof

Then there are the worker’s personal factors to consider, such as the:

  • clothing and equipment being worn
  • type of physical activity being done and the length of time it is done for
  • physical fitness of the worker.

Indoor work environments can increase the risk of workers being exposed to heat-related illness.

Non air-conditioned work environments can pose their own challenges because they can be more exposed to outdoor environmental conditions but have limited options for natural airflow and ventilation – whether due to the building’s design, layout and/or construction materials used. This means seasonal variances within the workplaces must also be considered.

It should be noted that in periods of excessive and/or extended hot weather, depending on the insulation and construction materials used in the building or structure, it is not uncommon for:

  • the temperature inside non air-conditioned premises to exceed the external air temperature, and
  • the building, once ‘heated up’ and depending on the construction and insulation, may retain heat for some period of time.

PCBUs with non air-conditioned workplaces must know when their workers could be at risk of exposure to heat-related illness and have systems in place to eliminate the risks so far as is reasonably practicable, then reduce the risks and monitor exposed workers.

Further information
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