Avoiding heat stress in the workplace

Many occupations expose employees to hot working environments. Work with hot plant (ovens) or in hot surroundings creates the potential for heat-related illness. Workload and clothing can also be factors in heat stress for workers.

The way the body reacts to the heat stress is known as heat strain. It is important to distinguish between a condition which threatens health and safety and one which results in a feeling of discomfort.

Heat-related illness ranges from prickly heat, to heat cramps, fainting, heat exhaustion and heat stroke. Heat stroke, although uncommon, is the most serious illness and can lead to death.

Under current safety legislation, all persons conducting a business or undertaking must ensure they eliminate or minimise risks so far as is reasonably practicable. To ensure your business is adequately prepared to respond to and manage the risk of heat stress, systems should be in place to monitor the workplace. These systems should:

• identify hazards
• assess risks to identify controls
• implement controls to eliminate or reduce risk
• review control measures.

This risk-based approach must be undertaken in consultation with identified stakeholders such as employees and contractors.

Identifying hazards

The effects of heat on the body are influenced by environmental factors including:

• air temperature (how hot the surrounding air is)
• humidity (the moisture content in the air)
• air movement (air speed and circulation)
• radiant heat (heat radiating from the sun, or emitted by plant, buildings, fixtures or processes)
• work demands
• clothing worn, including personal protective equipment.

Personal risk factors (such as age, weight, diet and whether a person is on medication) should also be considered as they may increase the risk of heat stress.

In addition, a person’s degree of heat acclimatisation will affect the level of risk. Heat acclimatisation is a physiological process whereby the body is able to reduce the risk of heat strain (i.e. tolerate higher levels). Heat acclimatisation takes time and those not acclimatised will be at higher risk to heat exposure.

Risk assessment

In assessing the overall risk it is important to consider all risk elements, both environmental and personal. Not all risk elements need be present for there to be a significant risk of heat stress, although it is likely that more than one will be required. Special attention should be paid to personal risk factors, as these may cause issues even when environmental conditions are acceptable.

Any risk assessment should be undertaken in consultation with employees, as required by legislation.

Where a number of risk factors are present, a more detailed risk assessment is needed. For instance if the environmental conditions in the workplace are hot and humid and processes also involve manual work and/or wearing multiple layers of clothing.

Risk controls

As with other hazards, there is a hierarchy of controls that should be considered to reduce the risks involved, starting with elimination.

Eliminate, substitute and/or isolate the heat source

• Review the need for such sources of heat and/or the need to perform tasks outside.
• Investigate options to reduce the heat generated or released by processes.
• Change the workflow to reduce the employee’s proximity to heat.
• Isolate heat areas to minimise workers being near them.

Engineering controls

• Ensure sufficient insulation around heat sources.
• Provide barriers to shield or deflect people from heat.
• When outdoor work permits, provide shade cloth or temporary canopies.
• Introduce air flow.
• Introduce humidity controls.
• Provide equipment and mechanical assistance to ease work demands.
• Provide suitable clothing.
• Make cool water readily available.

Administrative and/or behavioural controls

• Simplify work methods to avoid demanding features.
• Schedule additional resources.
• Alter schedules to allow work during less demanding periods.
• Provide additional and more frequent breaks at cooler locations.
• Provide suitable personal protective apparel to allow air circulation along with a covering from direct heat.
• Provide suitable direct weather barriers including ensuring employees:
• wear long-sleeved clothing
• wear wide-brimmed hats
• use sunscreen with a high SPF rating
• engage in other basic sun-protection mechanisms.
• Provide replacement fluids.
• Regularly provide training on the dangers, symptoms, controls and reporting around heat stress for all who work in hot environments, associated supervisors, and first aid providers.
• With first aiders and supervisors, reinforce the key symptoms and responses.
• Ensure active and frequent monitoring of all at-risk employees.
• Continue to promote the issue through work group planning and communication sessions.

Workers and other persons must take reasonable care to comply and cooperate with the employer to effectively manage hot working environments.