Heat illness at work

January 28, 2026

Brenniston calendar page illustration of workplace first aid heat illness response.

Heat-related illnesses can progress rapidly and become life-threatening if not recognised and treated early.

Australia’s hot summers and increasingly frequent heatwaves place workers under significant physiological stress, particularly in outdoor and industrial environments, and in high-exertion duties.

Young workers under 25, older people, pregnant workers, those with underlying health conditions, and people unaccustomed to working in hot environments face a higher risk.

Understanding how heat illness develops, and how to respond, helps employers protect workers’ health, maintain productivity and meet their duty of care.

Why is heat illness a serious workplace safety issue in Australia

Heat illness is not limited to extreme environments.

It affects workers across construction, mining, agriculture, transport, manufacturing, warehousing, hospitality and emergency services, as well as office workers in poorly ventilated spaces.

Australian workplaces are increasingly exposed to prolonged heat events, high overnight temperatures and humid conditions that reduce the body’s ability to cool itself. When combined with physical exertion, PPE, dehydration or inadequate breaks, the risk escalates quickly.

Safe Work Australia identifies heat as a foreseeable hazard, meaning employers must assess and control the risk using practical measures such as job rotation, shade, ventilation, access to hydration, and training.

How the body responds to heat stress

The body regulates temperature primarily through sweating and increased blood flow to the skin.

When overwhelmed by dehydration, humidity, heavy workload or illness, the body’s internal temperature rises.

As heat stress increases, the body moves through stages:

Dehydration
Heat cramps
Heat exhaustion
Heat stroke

Each stage is progressively more dangerous. Early recognition and prompt action can stop this progression and prevent serious harm.

Dehydration

Dehydration is usually the earliest stage of heat illness and one of the easiest to prevent. It occurs when fluid loss exceeds intake, particularly following an unrelated episode of vomiting, diarrhoea or prolonged sweating. In hot Australian workplaces, dehydration can impair concentration, coordination and physical capacity long before severe symptoms appear

Cause: Inadequate fluid intake, often following vomiting or diarrhoea.

Indications: Mild-to-severe thirst, dry lips and tongue, decreased function, reduced and/or dark urine.

First aid

1. Ensure regular and plentiful water or electrolyte drink

2. Move to a cool area, rest and reassure, loosen restrictive clothing and remove unnecessary PPE

3. Avoid caffeine, fizzy drinks, alcohol, and salt tablets

4. Seek medical attention if no improvement

Heat cramps

Heat cramps are painful muscle spasms that occur during or after intense physical activity in hot or humid conditions. They often signal fluid and electrolyte imbalance and should never be ignored. In Australian workplaces, heat cramps frequently occur in the legs or abdominal muscles during sustained exertion.

Cause: Dehydration, excessive sweating, over-exertion or poor conditioning in hot or humid conditions.

Indications: Sudden pain or ongoing cramps in the leg and/or abdominal muscles.

First aid

1. Cease physical activity and rest in a cool environment

2. Replenish fluids with water or electrolyte drink

3. Stretch and massage the affected area

4. Seek medical attention if no improvement

Heat exhaustion

Heat exhaustion is a serious condition that develops when the body struggles to regulate temperature due to overheating and dehydration. It can escalate quickly and may progress to heat stroke if untreated. Australian workplaces must treat heat exhaustion as a medical emergency requiring immediate intervention.

Cause: Dehydration and over-heating.

Indications: Weakness, thirst, exhaustion, nausea, vomiting, dizziness, pale clammy skin, fainting, rapid weak pulse and rapid breathing.

First aid

1. Lay the person down in a cool area, loosen tight clothing and raise legs slightly

2. If semi-conscious or unconscious, call Triple Zero (000) for an ambulance, place the person in the recovery position, monitor airways and breathing, prepare for CPR

3. If alert and conscious, cool down with sprayed water or a shower and give frequent sips of water or electrolytes

4. Seek medical attention if no improvement

Heat stroke

Heat stroke is a life-threatening medical emergency and requires immediate action. It occurs when the body’s temperature regulation fails completely, leading to rapid internal overheating. Without urgent treatment, heat stroke can cause organ failure, brain injury or death.

Cause: The body’s inability to cool itself after over-heating.

Indications: High body temperature, flushed dry and hot skin, lack of sweating, intense thirst, dry swollen tongue, confusion, irritability, fainting, seizure or unconsciousness.

First aid

1. Call Triple Zero (000) for an ambulance

2. Move the person to a cool environment with air circulation and remove excess clothing

3. Spray or sponge with cool water, apply ice packs or wet towels to the armpits and groin, or cover the body with a wet sheet

4. Monitor airways and breathing, prepare for CPR

5. If the person starts shivering, cease cooling until it subsides

Who is most at risk of heat illness at work

Some workers are more vulnerable to heat stress due to physiological, environmental or situational factors.

Higher-risk groups include:

New starters or workers returning after absence
Young workers who may push physical limits
Older workers with reduced heat tolerance
Pregnant workers
People with heart disease, diabetes or kidney conditions
Workers taking certain medications
People working in PPE or confined spaces
Workers unaccustomed to hot conditions

Identifying these risks allows workplaces to implement targeted controls rather than relying on one-size-fits-all solutions.

Early warning signs workplaces often miss

One of the most dangerous aspects of heat illness is how easily early symptoms are dismissed.

Thirst, fatigue, cramps or dizziness are often attributed to “just the heat” or physical exertion.

However, ignoring early signs increases the likelihood of collapse, loss of consciousness or organ damage.

Training workers to speak up—and supervisors to act—plays a critical role in prevention.

Preventing heat illness through workplace controls

Prevention is always more effective than treatment.

Australian workplaces are expected to manage heat risks using a combination of engineering, administrative and behavioural controls.

Effective prevention strategies include:

Scheduling heavy work during cooler hours
Providing shaded or air-conditioned rest areas
Ensuring constant access to cool drinking water
Encouraging regular hydration breaks
Rotating tasks to limit heat exposure
Modifying PPE where possible
Allowing acclimatisation for new or returning workers
Monitoring weather forecasts and heat alerts

Role of training and workplace culture

Training ensures workers recognise symptoms early and feel empowered to act.

Just as important is a workplace culture that supports stopping work when conditions become unsafe.

Supervisors play a key role by:

Monitoring workers for signs of heat stress
Encouraging reporting without judgement
Enforcing rest breaks
Adjusting workloads proactively

When workers know their safety comes first, they’re more likely to speak up early—preventing emergencies.

Conclusion

Heat illness at work is preventable, but only when risks are recognised, symptoms are taken seriously and action is taken early.

With Australia’s hot climate and increasing heatwaves, workplaces must be proactive in managing dehydration, heat cramps, heat exhaustion and heat stroke.

By combining education, practical controls and confident first aid response, organisations can protect workers, meet their WHS obligations and reduce the potentially fatal consequences of heat exposure.