Cool Under Pressure: Reducing Heat Stress in the Workplace with Helmet Technology

How helmet solutions help meet OSHA's new regulations and protect workers from heat-related illnesses

• By Ben Lzicar
• Sep 10, 2024

As heat stress becomes an increasingly critical issue in industrial safety, head protection must evolve to not only shield the wearer from impacts but also mitigate heat stress. According to Page and Sheppard’s “Heat Stress: Ambient Temperature and Workplace Accidents in the US,” heat shocks significantly increase accident rates, while Hancock and Vasmatzidis’s “Effects of heat stress on cognitive performance: the current state of knowledge” found a link between heat stress and a rise in body temperature, leading to decreased cognitive performance. In a warming world, it is essential to protect workers from the impacts of heat stress by enhancing the breathability and thermal regulation of their head protection.

This pressing issue of heat-related worker protection has caught the attention of regulatory bodies and industry leaders. OSHA has recently implemented federal guidelines to address heat stress, moving beyond consideration to concrete action. Several states have already enacted OSHA-approved state policies aimed at protecting workers from heat-related injuries and fatalities. According to the Centers for Disease Control and Prevention, an average of 702 heat-related deaths occur each year. Meanwhile, the Bureau of Labor Statistics reports that 528 work-related deaths due to environmental heat exposure occurred between 2011 and 2021 in the U.S. alone.

As heat-related injuries and fatalities continue to rise, finding innovative solutions for worker protection becomes increasingly crucial. In evaluating the thermal comfort of industrial helmets, the test results indicate a significant reduction in heat stress compared to traditional foam-based helmets. These advanced helmets are designed to address the demands of a warming world, offering enhanced protection while effectively reducing heat stress for workers. As industries strive to comply with the new OSHA guidelines, solutions like these are poised to play a vital role in safeguarding worker health and safety.

What is the Heat Index and Wet Bulb Temperature?

The body works hard to regulate temperature, primarily through the evaporation of sweat. Thermoregulation keeps body temperature at safe levels of around 37 degrees Celsius or 98.6 degrees Fahrenheit. As the surrounding relative humidity increases, the effectiveness of sweat evaporation decreases significantly. Thus, as temperature and humidity rise, so does the level of heat stress.

Additionally, human skin does not directly sense moisture; instead, it perceives moisture through a combination of temperature and tactile cues. This leads to a strong interaction between temperature and humidity perception.

OSHA now uses the Wet Bulb Globe Temperature (WBGT) as a more comprehensive measure to gauge heat risk levels, taking into account not just temperature and humidity, but also wind speed, sun exposure and other environmental factors. This broader pool of data provides a more accurate representation of the potential heat stress risks in a given environment, helping to protect workers from heat-related illnesses.

In the context of the microclimate inside workers’ helmets, the Heat Index is a useful metric for evaluating the overall heat experienced by the wearer. However, for assessing heat risk in broader workplace environments, the Wet Bulb Globe Temperature represents the new, more comprehensive standard. Both methods of measuring effective temperature have their respective roles in evaluating heat factors in the workplace. It is crucial for health and safety experts to understand the differences between the two to effectively manage heat stress.

Test Setup

Recognizing the need for better evaluation methods, it was necessary to develop a test protocol to assess the thermal comfort of industrial helmets. This method involved using a head form that simulates human sweating. The head form, equipped with a semipermeable membrane that only allows water vapor to pass, mimics human thermoregulation in a controlled setting. A water basin heated to 37 degrees C or 98.6 degrees F was used to replicate skin temperature and the build-up of humidity.

Helmets were tested at room temperature, with the head form set at 37 degrees C or 98.6 degrees F. The humidity and temperature were monitored for over an hour. Sensors placed around the head form collected data on temperature, relative humidity and absolute humidity, which were then used to calculate the heat index (HI).

This comprehensive approach ensures that the evaluation reflects real-world conditions as closely as possible. By simulating actual workplace environments, this testing method provides a more accurate assessment of how their helmets perform under various thermal conditions. This level of detailed analysis is crucial in developing protective gear that not only meets but exceeds current safety standards, ensuring that workers are protected in increasingly extreme environmental conditions.

Results

The test results showed a significant reduction in heat stress for helmets with welded tube construction compared to traditional foam-based helmets. These safety helmets demonstrated a reduction in head index of up to 4.5°C/8°F.

The engineered core structure, which is 95 percent air, allows heat and humidity to escape, aiding in thermoregulation and providing greater comfort during prolonged use. This feature reduces the risk of heat-related injuries and fatalities by improving airflow and preventing sweat accumulation. Importantly, this can also help prevent the temptation to remove PPE in hot conditions, which can lead to injuries or fatalities. It is crucial for employers to understand how their choice of PPE, particularly helmets, impacts their workers' health. Investing in advanced protective solutions like those incorporating welded tube technology is vital in addressing the increasing global temperatures and ensuring the safety and well-being of workers.

As we continue to face the challenges of a warming climate, the importance of heat stress mitigation in the workplace cannot be overstated. Employers must prioritize not only the physical protection of their workers but also their thermal comfort. By adopting advanced PPE solutions that incorporate innovative technologies, industries can better safeguard their workforce against the growing threat of heat-related illnesses and enhance overall safety and productivity.

This article originally appeared in the September 2024 issue of Occupational Health & Safety.