Heat stress management: a plan for hot working conditions

Heat stress management means working out where and when your workers are exposed to heat, putting controls in place, and responding quickly when someone shows signs of heat illness. The person conducting the business or undertaking (PCBU) must manage heat risks so far as is reasonably practicable under the primary duty of care. The WHS laws don't name a heat stress plan, but in practice a written plan covering assessment, controls, training, monitoring and emergencies is the clearest way to show you've done it.

What heat stress is

Heat stress happens when the body can't cool itself. Sweating stops working well, core temperature rises, and fluids and electrolytes are lost. It's caused by a mix of high temperature, humidity, physical work, hot plant, poor airflow and clothing that traps heat. Outdoor work in direct sun, enclosed spaces such as tunnels and roof cavities, and work in sealed or heavy PPE all raise the risk.

Heat stress can get worse quickly, so learn the signs early. The table below sets out the common stages.

Treat any confusion or collapse as an emergency, even if the person says they feel fine.

Find where the heat risk is

Start by working out where people are exposed. Look at three things:

• The environment. Air temperature, humidity, direct sun and airflow. Measure at different times of day, because the afternoon can be very different from the morning. A Wet Bulb Globe Temperature (WBGT) monitor, a heat index chart or an infrared thermometer gives you consistent readings.
• The tasks. Outdoor work such as construction, landscaping, farming and utility repairs. Indoor work near furnaces, ovens, boilers and hot metal. Heavy lifting or sustained physical effort. Work in unventilated spaces like attics, basements and tunnels.
• The equipment. Hot plant surfaces and radiant heat from machines, and any heavy or sealed PPE that stops the body from cooling.

Then identify the people who are most at risk. New workers and anyone not yet used to hot conditions are a priority, because they haven't acclimatised. Older workers, people with health conditions and people wearing heavy PPE also need closer attention.

Control the risk

Use the hierarchy of controls and start with the most effective measures:

Engineering and administrative controls do most of the work. PPE helps, but it's the last line of defence. Make sure water is available in quantity, and that people drink it before they feel thirsty.

Where plant can't be moved away from workers, shield or insulate hot surfaces to cut radiant heat. Our guide to managing the risks of plant in the workplace covers plant-related hazards in more detail.

Train your crew

Controls only work if people know what they're for. Training should cover:

• The warning signs of heat illness, and how to tell a heat cramp from heat stroke
• First aid for heat emergencies, including cooling
• How to use cooling equipment and when to take breaks
• Why drinking enough fluid matters, and how to notice dehydration

Run refresher training before the hot weather starts, and again during a heatwave. Hands-on practice works better than a slideshow. Run a drill for a mock heat stroke, so the crew knows who calls 000, who gets the cooling kit and who stays with the casualty. Put a simple poster with the signs and the response near the water supply.

Monitor and review the plan

A heat plan has to keep working through the season. Build in a few regular checks:

• Temperature logs for each work area, recorded through the day
• Worker feedback, through a short survey, a toolbox talk or an anonymous report
• Incident and near-miss reports for any heat-related problem

Use what you find to adjust the controls. If people aren't drinking enough, add water stations. If breaks aren't working, change the work-rest cycle or add cooling. If one task keeps causing heat illness, move it to cooler hours or make it less physically demanding.

A short daily checklist keeps this simple:

• Are temperatures recorded for the day?
• Does everyone know the heat stress signs?
• Are water and rest areas stocked and accessible?
• Are the rest areas shaded or cooled?
• Were there any heat-related incidents or near misses?

Do you need a written heat plan?

The WHS laws require you to manage risks from extremes of heat and cold. The guide for managing the risks of working in heat and the code of practice for managing the work environment and facilities give practical guidance on how to do it. Neither names a heat plan as a legal requirement, but a written plan is the most practical way to show that you've assessed the risk, controlled it and reviewed it.

Heat can also be a hazard in a SWMS for outdoor high-risk construction work, so include it in the SWMS where it applies.

Templates to start from

• A heat stress SWMS for high-risk work in hot conditions
• A hot conditions safety policy to set the rules for everyone on site
• A hot conditions risk assessment form to record each area and task

How SafetyDocs helps

Most crews don't have time to write a heat plan from scratch, and the hot conditions documents often sit in a folder nobody opens until the first heatwave. SafetyDocs gives you expert-written heat templates, with your job, client and site details filled in. Workers can read the document and sign it on their phone from a text or QR code, and when the plan changes, everyone who signed the old version is asked to sign the new one.

Common questions

Do I need a heat stress management plan? The WHS laws require you to manage heat risks, and a written plan is the practical way to do that. Your state regulator can tell you what it expects for your industry.

What temperature should work stop at? The law doesn't set one temperature that stops work everywhere. Base the decision on your risk assessment, monitoring and conditions on the day, and write the trigger into your plan.

What do I do if a worker collapses in the heat? Call 000 straight away. Move the person to a cool area, cool them quickly with water, and stay with them until help arrives.

Do workers have to drink water every hour? The aim is that workers can drink enough without asking. Make water available in quantity, encourage regular drinking, and build breaks into the schedule.

This is general information, not legal advice. Check the current law with your WHS regulator.