TT Talk - The effects of heat stress and how to effectively manage the risk

A changing climate is creating new challenges for ports and supply chain operations. For many years, heat stress has been regarded as a risk primarily associated with tropical, desert, or traditionally hot regions of the world. Today, that assumption is becoming increasingly outdated. 

Across Europe, North America and other historically temperate parts of the globe, record-breaking temperatures and prolonged heatwaves are becoming more common. Locations that have not traditionally experienced extreme heat are now facing conditions that can present significant risks to worker health, operational performance and safety. 

For operators across ports, terminals, warehouses, transport networks and logistics facilities, this changing climate pattern should prompt an important question: have existing risk assessments kept pace with the changing environment? 

The consequences of heat stress extend well beyond worker discomfort. When the body struggles to regulate its temperature, physical and cognitive performance can deteriorate rapidly. Concentration, decision-making, reaction times and situational awareness may all be affected. In safety-critical environments, these changes can increase the likelihood of incidents, injuries and operational disruption. 

In safety-critical environments, these changes can increase the likelihood of incidents, injuries and operational disruption. 

As global temperatures continue to rise, organisations should ensure that heat stress is not viewed as an occasional seasonal issue but as a workplace hazard requiring the same systematic management approach applied to other significant risks. 

Understanding the hazard 

According to guidance published by the US National Institute for Occupational Safety and Health (NIOSH), heat stress occurs when the body's means of controlling its internal temperature becomes overwhelmed by environmental conditions and physical exertion. The World Health Organisation helpfully outlines that the core temperature of the body should not exceed 38°.  

Early symptoms are wide ranging and will inevitably differ from one individual to another depending on a range of physiological and environmental factors but will typically include headache, nausea, dizziness, weakness, irritability, confusion and heavy sweating. The subsequent effects can range from mild heat rash and heat cramps through to heat exhaustion and, in severe cases, life-threatening heat stroke. However, the indirect consequences can be equally important. Heat can contribute to fatigue, reduced alertness, impaired judgement and slower reactions, all of which have significant implications in operational environments involving vehicles, lifting equipment, cargo handling and vessel operations. 

The challenge can be particularly acute within ports and logistics facilities where workers may be exposed to: 

• Direct sunlight and radiant heat 
• High humidity 
• Physically demanding work 
• Long shifts or irregular working patterns 
• The additional thermal burden created by personal protective equipment (PPE) 

Importantly, workers may not always recognise their own level of impairment. Research into fatigue management has consistently demonstrated that individuals are often poor judges of their own alertness, meaning that reliance on self-assessment alone is unlikely to provide an effective safeguard. 

Lessons from fatigue management 

The port sector has already demonstrated the value of adopting a structured approach to managing human performance risks. 

As highlighted in the forthcoming edition of the Port Authority Bulletin, the Port Industry Association (PIA) in New Zealand has received significant recognition for its work in developing industry-wide fatigue management guidance. The collaborative project brought together regulators, worker representatives, industry stakeholders and academic expertise to create practical, science-based guidance tailored specifically to the realities of port operations. 

The resulting Building a Fatigue Risk Management System guidelines emphasise several principles that are equally relevant to heat stress management: 

• Risks should be identified and assessed systematically  
• Control measures should be monitored and reviewed  
• Workforce participation and engagement are essential 
• Organisations should foster a "just culture" that encourages reporting of concerns 
• Risk management should be based on data, science and operational experience 

These principles provide an excellent foundation for addressing the growing challenge of heat stress. Rather than relying on ad hoc measures during a heatwave, operators should consider whether a more structured heat stress management framework is required. 

Reassessing risk in a changing climate

One of the greatest dangers associated with climate change is the tendency to base risk assessments on historic conditions. 

Regions that previously experienced only a handful of hot days each year may now encounter sustained periods of extreme heat. Infrastructure, work schedules, welfare facilities and emergency arrangements that were suitable in the past may no longer provide adequate protection. 

Infrastructure, work schedules, welfare facilities and emergency arrangements that were suitable in the past may no longer provide adequate protection. 

Operators should review: 

• Historical temperature records alongside emerging climate trends 
• Tasks involving prolonged outdoor work 
• Areas with poor ventilation or high radiant heat 
• Exposure associated with vehicle cabs, warehouses and cargo handling equipment 
• Emergency response arrangements for heat-related illness 
• Whether existing PPE significantly increases thermal stress 

Heat stress should also be considered in conjunction with other factors such as fatigue, dehydration and shift work, all of which can compound the risk. 

Practical measures to reduce heat stress 

NIOSH recommends a combination of engineering controls, administrative controls and worker education to manage heat-related hazards effectively. 

Increase awareness and training 

Workers and supervisors should be trained to recognise symptoms such as heat cramps, heat exhaustion, heat stroke along with early warning signs such as dizziness, headaches, excessive sweating, confusion, or weakness. 

Training should also cover emergency response procedures and the importance of reporting symptoms promptly. 

Support acclimatisation 

One of the most effective controls is ensuring workers develop tolerance to hot conditions gradually. 

NIOSH recommends progressively increasing exposure to hot environments over a period of seven to fourteen days, particularly for new starters, workers returning from absence or personnel redeployed from cooler environments. 

This is increasingly relevant as heatwaves occur in regions where workers may have little previous experience of operating in extreme temperatures. 

Encourage hydration 

Adequate hydration remains fundamental. 

NIOSH recommends providing cool drinking water close to the work area and encouraging regular fluid intake rather than waiting until workers feel thirsty. Electrolyte replacement may also be appropriate during periods of prolonged sweating. 

Review work-rest schedules 

Work scheduling should be flexible enough to account for environmental conditions. Considerations may include moving physically demanding tasks to cooler periods of the day, increasing the frequency of rest breaks, providing shaded or air-conditioned recovery areas and rotating personnel undertaking high-exertion activities. 

Consider the impact of PPE 

Although essential for safety, PPE can impede the body's ability to dissipate heat. When assessing heat stress risks, organisations should consider whether alternative equipment can provide the same level of protection with reduced heat burden. Additional rest periods might be required when PPE is worn and the implementation of cooling strategies appropriate to the task and operating environment. 

Building resilience for the future 

Heatwaves are no longer isolated events affecting only a handful of regions. They are becoming an increasingly common operational reality across the global supply chain. 

The port sector's collaborative work on fatigue management, exemplified by the PIA initiative, demonstrates how industry-wide cooperation can deliver meaningful improvements in safety performance. Similar thinking should now be applied to heat stress. 

For organisations operating in locations that have not traditionally experienced prolonged periods of high temperature, now is the time to reassess risks, review existing controls and ensure workers are prepared for conditions that may soon become the new normal. 

review existing controls and ensure workers are prepared for conditions that may soon become the new normal. 

Managing heat stress effectively is not simply about responding to the next heatwave. It is about recognising a changing risk landscape and ensuring that people, operations and supply chains remain resilient in a warming world.