Heat Stress Monitoring

Heat stress can be a serious concern in industries that expose workers to high temperatures, such as defence, mining, construction, manufacturing, warehousing, food production, agriculture, and emergency services. Australia’s climate varies from arid and semi-arid conditions in the outback to tropical heat in northern regions. This diversity makes heat stress monitoring a crucial aspect of work health and safety for operations conducted within Australia.

Recent reviews of Australian workplaces reveal that workers in several industries regularly face extreme temperatures, ranging from 32°C to 42°C, often exacerbated by high humidity levels. Prolonged exposure to such conditions can significantly reduce productivity, pose severe health risks, and result in non-compliance with workplace safety regulations. As experienced occupational hygienists, we specialise in assessing, monitoring, and mitigating heat stress risks, ensuring worker safety and helping businesses meet their legal and safety obligations.

Why Heat Stress Monitoring is important

Heat stress can cause health conditions ranging from heat cramps to life-threatening heatstroke. In industries where physical exertion is high and workers face extreme heat, monitoring is essential to prevent:

Serious health risks, such as dehydration, heat exhaustion, and heatstroke.
Productivity loss, as workers exposed to high temperatures may experience fatigue and illness.
Non-compliance with work health and safety regulations, which can lead to penalties.

In Australia’s hottest regions, core body temperatures of workers have been found to exceed 39.5°C, especially among occupational groups such as emergency services and underground mining. Effective heat stress monitoring helps minimise risks and keeps workers safe.

Key Factors affecting Heat Stress

Heat stress is typically influenced by several factors:

Environmental conditions – Air temperature, humidity, wind speed, and radiant heat.
Job-related factors – Physical exertion, exposure duration, and task complexity.
Worker attributes – Acclimatisation, clothing, hydration status, and fitness level.

High metabolic heat production, coupled with intense physical activity, is a key driver of heat strain, particularly in jobs that demand sustained effort, such as construction, mining, and agriculture.

Regulatory Compliance and Industry Standards

Australia’s Work Health and Safety (WHS) Acts across our jurisdictions mandates employers provide safe working conditions, including protecting workers from heat stress. As occupational hygienists, we use international standards like ISO 7933: Ergonomics of the thermal environment — Analytical determination and interpretation of heat stress using calculation of the predicted heat strain to evaluate heat stress risks and help businesses remain compliant.

The Role of an Occupational Hygienist in Heat Stress Monitoring

Occupational hygienists play a crucial role in identifying, assessing, and mitigating heat stress risks in various industries. Their expertise in workplace health and safety allows them to apply a comprehensive approach to managing heat-related hazards, ensuring that workers are protected from the physical strain caused by high temperatures.

1. Risk Identification and Assessment

An occupational hygienist conducts thorough workplace assessments to identify potential heat stress risks. This involves evaluating environmental factors such as air temperature, humidity, and radiant heat, as well as job-specific variables like physical exertion and the use of personal protective equipment (PPE). In industries such as mining, construction, and agriculture, where workers are regularly exposed to high temperatures, these assessments are critical for preventing heat-related illnesses.

Heat stress monitoring devices/tools Used:

Wet Bulb Globe Temperature (WBGT) meters to assess environmental heat load.
Physiological monitoring devices that measure workers’ core body temperature, heart rate, and sweat rate in real time.
Predictive models, such as ISO 7933’s Ergonomics of the thermal environment — Analytical determination and interpretation of heat stress using calculation of the predicted heat strain (Predicted Heat Strain (PHS)), to assess worker strain and calculate safe work-rest cycles

2. Implementation of Control Measures

Based on the results of risk assessments, occupational hygienists can assist organisations to develop and implement control measures to reduce workers’ exposure to excessive heat. These controls can be:

Engineering controls such as improving ventilation, providing shaded work areas, or installing cooling systems to lower ambient temperatures.
Administrative controls such as adjusting work schedules to avoid the hottest parts of the day, mandating frequent rest breaks, and ensuring workers are properly hydrated.
Personal protective equipment (PPE) management – Ensuring that workers wear appropriate clothing for heat dissipation and, when appropriate, using personal cooling systems such as ice vests.

3. Continuous Heat Stress Monitoring and Worker Training

Occupational hygienists can set up continuous monitoring systems in high-risk environments. Real-time heat stress monitoring tools, such as wearable heat monitors or ingestible temperature sensors, allow for immediate intervention when a worker’s core body temperature or heart rate exceeds safe levels.

In addition to monitoring, our team can conduct training programs to educate workers on:

Recognising the early signs of heat stress such as excessive sweating, dizziness, or fatigue.
Proper hydration strategies, including when and how much to drink to avoid dehydration.
Appropriate use of PPE and other personal cooling measures to mitigate the effects of heat exposure.

4. Compliance with Regulatory Standards

Helping companies comply with workplace health and safety regulations is a critical responsibility of occupational hygienists. In Australia, the various Work Health and Safety (WHS) Acts requires employers to provide safe working environments, including addressing heat stress risks. By following standards such as ISO 7933 and Thermal Work Limit (TWL), occupational hygienists can help companies ensure that the control measures and monitoring systems they implement meet regulatory requirements.

5. Tailored Solutions for High-Risk Industries

Our occupational hygienist can also develop customised heat stress management programs for industries with elevated risks, such as:

Mining – Where underground workers are exposed to high heat and humidity.
Agriculture – Where prolonged outdoor exposure leads to heat strain.
Construction – Where tasks are performed under direct sunlight with high physical exertion.
Emergency service – Where workers, especially firefighters, face extreme radiant heat.

By tailoring solutions to specific industries and specific workplaces, our occupational hygienists help mitigate heat stress risks effectively, ensuring worker safety and maintaining productivity.

Industries with High Heat Stress Risk

Heat stress risks are most pronounced in industries where workers are exposed to extreme environmental conditions and engage in physically demanding tasks. The following section outline industries where heat stress can be a significant concern, and we explain how heat stress monitoring can mitigate risks.

1. Agriculture

In the agricultural sector, workers are exposed to prolonged periods of outdoor activity in hot conditions. Agricultural workers in Australia, particularly in regions like South Australia and Queensland, can face temperatures between 32°C and 41°C. Tasks such as sheep shearing, fruit picking, and harvesting may require sustained physical effort, and the heat generated from metabolic activity can lead to high core body temperatures.

Shearers, for example, have been reported to lose up to 9 litres of sweat during a single day of shearing in hot weather. The intense physical nature of this job, combined with radiant heat from the environment, significantly increases the risk of heat exhaustion and dehydration.

Key Heat Stress Monitoring Strategies:

WBGT and PHS assessments to monitor environmental and physiological stress.
Real-time physiological monitoring to track core body temperature and heart rate.
Engineering controls such as shaded areas and hydration stations to reduce exposure.

2. Construction

The construction industry exposes workers to high heat during outdoor activities like laying foundations, framing, and tying steel reinforcements. In Western Australia, research shows that workers are regularly exposed to temperatures exceeding 37°C during the summer months. High physical exertion and exposure to direct sunlight make heat stress a critical concern in this industry.

Real-time physiological monitoring and WBGT assessments are necessary to prevent heat-related illnesses in construction workers. Additionally, the use of impermeable protective gear can exacerbate heat stress by reducing sweat evaporation, making monitoring even more critical.

Key Heat Stress Monitoring Strategies:

WBGT and Heat Stress (Basic) Calculator for initial risk assessments.
Advanced monitoring tools to track heat stress in workers wearing PPE.
Work-rest schedules and break times based on environmental conditions to allow recovery.

3. Mining

Mining, particularly underground mining, presents one of the highest risks for heat stress due to both environmental heat and metabolic heat from physical exertion. In mining regions like Mount Isa, Queensland, core body temperatures of workers have been recorded as high as 39.5°C. Deeper mines can result in high heat and humidity, creating extreme working conditions.

Key Monitoring Strategies:

WBGT assessments to measure the environmental heat load.
Wearable heat monitors to track core temperature and heart rate in real time.
Personal cooling systems for workers exposed to high heat and humidity for extended periods.

4. Emergency Services

Workers in emergency services, such as firefighters and rescue personnel, are often exposed to extreme heat while wearing heavy protective gear. Research shows that Bushfire fighters have been recorded with core body temperatures as high as 39.6°C during active fire suppression activities. The combination of physical exertion, protective clothing, and radiant heat from fires makes heat stress a concern for bodies responsible for co-ordinating fire and emergency services operations.

Key Monitoring Strategies:

Physiological monitoring devices to track body temperature, heart rate, and sweat rate during emergency operations.
Cooling equipment, such as ice vests, to help reduce body temperature.
Work-rest cycles to limit continuous exposure to extreme heat.

5. Warehousing and Food Production

Warehousing and food production can, at times, present unique heat stress risks due to confined spaces and the presence of heat-generating machinery. In warehousing environments, inadequate ventilation can trap heat, while in food production facilities, radiant heat from ovens and cooking equipment can significantly raise temperatures. Our experience shows that workers may periodically experience heat stress events, particularly in areas with limited airflow.

Key Heat Stress Monitoring Strategies:

WBGT assessments to monitor heat from machinery and environmental conditions.
Ventilation improvements to ensure proper airflow.
Hydration stations and cooling breaks to help workers manage heat stress.

6. Military and Defence

While it’s accepted that military personnel are often required to perform physically demanding tasks excessive heat in Australia can have devastating effects of military personnel health

Research show that in Northern Queensland, soldiers on patrols and forced marches have reported core body temperatures exceeding 39.5°C, especially when carrying heavy packs and equipment. These conditions, combined with the physical demands of military operations, make heat stress monitoring particularly critical in the military sector.

Key Monitoring Strategies:

Wearable monitors to track real-time physiological data during training and operations.
Predictive heat strain models to assess the impact of heavy load-carrying on heat production.
Cooling devices and hydration protocols to prevent heat-related illnesses.

Advanced Technologies in Heat Stress Monitoring

To effectively manage heat stress, we use the latest technologies:

Wearable Heat Monitors – These devices track core body temperature, heart rate, and sweat rate in real time, allowing immediate intervention when workers reach dangerous heat levels.
WBGT Meters – These meters measure temperature, humidity, and radiant heat to assess the environmental heat load.

Implementing a Heat Stress Management Program

A comprehensive heat stress management program includes:
Regular Assessments – Using advanced monitoring tools to assess heat stress risks periodically.
Worker Training – Educating workers on the importance of hydration, recognizing heat stress symptoms, and using protective equipment.
Control Measures – Implementing administrative controls, such as work-rest schedules, and engineering controls, like improved ventilation and shaded areas.
Real-Time Monitoring – Using wearable technology in high-risk environments to continuously monitor workers’ physiological responses.

Legal Liabilities from Heat Stress Events

Heat stress in the workplace presents significant legal risks for employers, who are required by law to ensure a safe working environment. Under Australia’s Work Health and Safety (WHS) Act, employers have a duty of care to manage and mitigate hazards such as heat stress. Failure to do so can lead to legal consequences, including fines, compensation claims, and reputational damage.

Breach of Duty of Care

Employers are legally obligated to protect their employees from foreseeable health risks, including heat stress. If an employee suffers a heat-related illness due to inadequate controls, the employer may be found in breach of their duty of care. This can result in:

Prosecution and fines – Regulatory bodies like Comcare and state agencies such as WorkSafe Victoria, Safework NSW and Worksafe Qld may prosecute employers for failing to comply with safety regulations, potentially resulting in hefty fines.
Compensation claims – Employees who suffer from heat stress can file compensation claims, seeking reimbursement for medical expenses, rehabilitation, and lost wages. Prolonged or severe cases could lead to claims for permanent disability, further increasing liability for the employer.

Failure to Comply with WHS Regulations

Employers must comply with regulations related to heat stress management. For instance, the Managing the Work Environment and Facilities Code of Practice and SafeWork Australia’s guidelines outline requirements for controlling hazards, including excessive heat. Failure to comply can result in:

Regulatory penalties -If employers do not conduct heat stress risk assessments, provide sufficient breaks, hydration, or cooling measures, they may face significant fines.
Worker compensation claims – Employees exposed to extreme temperatures without adequate protection can seek compensation, leading to financial liabilities for the employer.

Negligence and Personal Injury Claims

Workers who suffer from heat-related illnesses may file personal injury lawsuits against their employer, especially if they can demonstrate negligence. Negligence claims can be based on:

Failure to conduct proper risk assessments for heat stress.
Inadequate training or insufficient information provided to employees about heat risks.
Insufficient or inappropriate control measures, such as failing to provide hydration, cooling areas, or adjusting work schedules to avoid peak heat.

Reputational Damage

In addition to financial and legal repercussions, a failure to manage heat stress risks can severely damage a company’s reputation. Heat stress incidents, especially those leading to hospitalisations or fatalities, can attract media attention, damage employer branding, and create difficulty in retaining and attracting talent.

The Role of Monitoring as a Defence

Employers can significantly strengthen their legal defence by implementing continuous heat stress monitoring. Monitoring not only improves worker safety but also provides documented evidence that the employer is taking proactive steps to manage heat risks.

Demonstrating Due Diligence

Regular monitoring of heat stress conditions, such as using Wet Bulb Globe Temperature (WBGT) meters and other wearable physiological monitors, demonstrates that an employer is actively managing heat-related hazards. By consistently tracking environmental and physiological data, employers can show they are meeting their duty of care and taking reasonable steps to protect workers from heat stress.

Providing Objective Evidence

Monitoring provides objective data that can be used as evidence in legal proceedings. If a heat stress incident occurs, data logs showing temperature, humidity, and worker physiological responses can demonstrate that conditions were within acceptable safety thresholds and that interventions were made when necessary.

Compliance with Regulations

Continuous heat stress monitoring helps employers comply with SafeWork Australia and other regulatory guidelines. By documenting environmental conditions and worker responses in high-risk environments, employers can show they are fulfilling legal obligations, which can be critical in defending against claims of negligence or non-compliance.

Identifying Real-Time Hazards

Monitoring helps identify heat stress hazards in real time, allowing for immediate action to be taken. For example, if a worker’s body temperature or heart rate exceeds safe levels, employers can intervene by stopping work, moving workers to cooler areas, or providing hydration. This not only protects the worker but also helps build a defence by showing that steps were taken to prevent harm.

Enhancing Worker Safety Programs

By incorporating monitoring into heat stress management programs, employers can further demonstrate their commitment to worker safety. Documenting regular assessments, using advanced monitoring tools, and providing proper training show that heat stress risks are being proactively managed, which can help mitigate potential liabilities.

Conclusion

Heat stress poses significant risks in various industries, particularly in agriculture, mining, construction, emergency services, warehousing, and food production. Our team of occupational hygienists provides tailored heat stress monitoring solutions, ensuring compliance with safety regulations and safeguarding workers’ health. By implementing advanced monitoring tools, real-time physiological assessments, and proactive interventions, we help workplaces minimise the risks associated with heat stress and create safer, more productive environments.

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Have a question on our heat stress monitoring services or need a quotation for heat stress monitoring? Call one of our friendly team on 1300 087 888.

References

1. Safe Work Australia. (2019). Guide for Managing the Risks of Working in Heat. This guide provides a comprehensive overview of managing heat risks in Australian workplaces, including risk assessments, control measures, and strategies to mitigate heat stress in different industries. [Available here]

2. Safe Work Australia. (2019). Managing the Work Environment and Facilities Code of Practice. This document outlines the minimum requirements for providing a safe work environment, including temperature management and ventilation, which are key to controlling heat stress. [Available here]

3. WorkSafe Victoria. (2021). Working in Heat, A practical guide on addressing heat-related hazards in the workplace, focusing on both indoor and outdoor environments. It provides specific solutions and examples of heat stress management. [Available here]

4. SafeWork NSW. (2020). Managing extreme heat at your workplace, This guide offers practical advice for employers on how to manage heat stress risks in workplaces, highlighting the importance of acclimatization, hydration, and appropriate clothing. [Available here]

5. Australian Institute of Occupational Hygienists (AIOH). (2013). A Guide to managing heat stress, This position paper by the AIOH offers a deep dive into the assessment of occupational heat stress, providing best practices and methodologies used by occupational hygienists in Australia. [Available here]

6. ISO 7933:2004. Ergonomics of the thermal environment — Analytical determination and interpretation of heat stress using calculation of the predicted heat strain. This international standard provides a framework for determining heat stress in workers through the calculation of predicted heat strain (PHS). [Available here]

7. WorkSafe Queensland. (2019). Heat Stress, This guide addresses the prevention of heat stress, [Available here]

8. Australian Government Bureau of Meteorology. (2020). Heatwave: Knowledge Centre. An overview of heatwaves in Australia, their frequency, intensity, and impacts on public health, with a focus on workplace safety during extreme heat events. [Available here]

9. Blesson M Varghese, Alana Hansen, Nick Mann, Jingwen Liu, Ying Zhang, Tim R Driscoll, Geoffrey G Morgan, Keith Dear, Anthony Capon, Michelle Gourley, Vanessa Prescott, Vergil Dolar and Peng Bi, 2023, The burden of occupational injury attributable to high temperatures in Australia, 2014–19: a retrospective observational study, Published online at https://www.mja.com.au/journal/2023/219/11/burden-occupational-injury-attributable-high-temperatures-australia-2014-19 [Accessed 4/10/2024]

10. Extreme Heat Safety: What Should You Do Before Extreme Heat Occurs? Red Cross, Online at https://www.redcross.org/get-help/how-to-prepare-for-emergencies/types-of-emergencies/extreme-heat-safety.html [Accessed 4/10/2024]