Occupational thermal stress: what it is and how to prevent it

Workers’ exposure to extreme temperatures affects productivity and can pose a risk to their health. In some parts of Spain, weather conditions expose professionals who work outdoors to below-zero temperatures during the winter months and extreme heat in summer. Likewise, there are indoor jobs that also involve challenging environmental conditions. In both circumstances, workers are exposed to occupational thermal stress. 

The various regulations aimed at preventing occupational risks in Spain include occupational thermal stress among them. This is the case of Royal Decree 486/1997, which establishes the minimum health and safety provisions in workplaces. It addresses this concept in greater depth in its annex, “Environmental conditions in workplaces”. More specifically, the National Institute for Safety and Health at Work (INSST) produced a Technical Guide for the Assessment and Prevention of Risks Related to the Use of Workplaces which, updated in 2015, proposes a pathway to reduce risks and improve the wellbeing of professionals who, among other situations, are exposed to extreme temperatures.  

What is occupational thermal stress?  

Occupational thermal stress is understood as the feeling of discomfort experienced by workers due to imbalances in body temperature caused by excessive heat loss or accumulation. According to this definition, there can be heat stress or cold stress. 

This circumstance can occur in both outdoor and indoor work. In either case, there are factors that increase the risk of occupational thermal stress: 

• Older age. Older people’s bodies are more vulnerable, taking longer to acclimatise to extreme conditions. 
• Physical fitness. Poor physical fitness reduces resistance to extreme situations and increases susceptibility to cardiovascular disorders. In particular, at high temperatures, being overweight increases the risk of occupational thermal stress.
• Medical history. Conditions such as diabetes, kidney failure, or respiratory tract or cardiovascular system disorders affect adaptation to extreme temperatures, so people who have them should not carry out work that may cause occupational thermal stress. 
• Medication. It is necessary to know the effects of the medications taken by workers, as some of them influence thermoregulation, reducing the distribution of body heat.  

Based on these shared concepts, it should be noted that there are significant differences between occupational cold stress and heat stress. The National Institute for Safety and Hygiene at Work has produced two Technical Prevention Notes setting out the consequences and recommended good practices to reduce the risk of cold stress -NTP Cold stress- and heat stress -divided into two NTPs: Thermal stress and thermal strain: risk assessment (I) and Thermal stress and thermal strain: risk assessment (II)-. 

How can occupational thermal stress be prevented?   

Based on these recommendations, and taking into account each worker’s personal circumstances, it is possible to implement a series of preventive measures that reduce the risk of occupational thermal stress. It is important, however, to distinguish between cold and heat stress, as the needs in each case are different.  

Measures to prevent occupational heat stress 

High temperatures are common in Spain in summer, with heatwaves exceeding 40 degrees across much of the country.   Taking preventive measures for professionals who work outdoors during the summer is essential to maintain productivity and reduce the risk of occupational thermal stress. 

For this reason, the INSST has developed a website outlining the main measures that should be implemented to protect workers’ health and safety. Similar precautions should also be taken in indoor roles that require direct and continuous contact with high temperatures. Here are the main ones:

• Provide equipment with loose-fitting garments made from lightweight fabric and suitable, breathable footwear. 
• Protect the head with a hat or cap to prevent the sun from directly affecting the worker. 
• Establish an acclimatisation period to hot conditions of between 7 and 15 days. 
• When working outdoors, carry out work planning that reduces or avoids exposure during the middle of the day. 
• For indoor work, where possible, install climate-control equipment at the workstation. When work circumstances prevent this, establish nearby air-conditioned spaces that allow workers to rest at an appropriate temperature. 
• Maintain constant hydration.
• Increase rest periods.
• Provide places for breaks in shaded areas or, where possible, in air-conditioned rooms. 
• Provide mechanical aids when handling loads and limit tasks that require lifting heavy weights. 
• Encourage teamwork, ensuring that no professional works without colleagues nearby. 
• Reapply sunscreen frequently. 
• Train workers in specific good practices to prevent occupational thermal stress in their role. 

Measures to prevent occupational cold stress 

Occupational exposure to cold environments can alter workers’ body temperature, causing health problems. Taking appropriate preventive measures can reduce the risks associated with exposure to cold at work, whether outdoors during the harshest winter months or in indoor spaces with very low temperatures.

• Have specific protective clothing. Garments must provide thermal insulation and protection against moisture. Learning about the essential equipment for working in cold storage rooms can serve as a guide to the type of suitable clothing. 
• Adequate protection for the extremities. The parts of the body that are in direct contact with surfaces are key to preventing cold stress. In this regard, there is a specific Technical Note focusing on “Protective clothing and gloves against cold”. Likewise, feet are an area of the body that is especially sensitive to low temperatures, so workers need professional footwear that keeps them warm and also has a slip-resistant sole to reduce the risk of slips. These boot models for working in cold environments meet these needs. 
• Take regular breaks in designated heated areas.
• Schedule outdoor activities according to the weather forecast, avoiding the hours with the lowest temperatures. 
• Regularly check that alert devices are working properly when working indoors.
• Use mechanisms that reduce manual handling. 
• For outdoor workstations, provide radiant heat devices. 
• Provide ongoing training for workers on the protective measures they should take into account. 

Having suitable footwear is essential to reduce the risk of workers experiencing occupational thermal stress. The Shoes For Crews catalogue includes a wide variety of quality models suitable for the most extreme environmental situations. In addition, our patented slip-resistant sole is perfectly suited to complex work environments. Contact us and we will help you find the most suitable footwear for your team.