Page 30 - OHS, September 2024

PPE: HEAD & FACE PROTECTION
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
As heat stress becomes an increasingly critical issue in in- dustrial 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 Vas- matzidis’s “Effects of heat stress on cognitive performance: the cur- rent 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 im- pacts of heat stress by enhancing the breathability and thermal regu- lation 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, mov- ing beyond consideration to concrete action. Several states have already enacted OSHA-approved state policies aimed at protect- ing 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 com- pared to traditional foam-based helmets. These advanced helmets are designed to address the demands of a warming world, offer- ing 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 temper- ature at safe levels of around 37 degrees Celsius or 98.6 degrees Fahrenheit. As the surrounding relative humidity increases, the ef- fectiveness 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; in- stead, it perceives moisture through a combination of temperature and tactile cues. This leads to a strong interaction between tem- perature 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,
It is crucial for health and safety experts to understand the differences between the Heat Index and Wet Bulb Globe Temperature to effectively manage heat stress.
sun exposure and other environmental factors. ThThis 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 expe- rienced by the wearer. However, for assessing heat risk in broader workplace environments, the Wet Bulb Globe Temperature rep- resents 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 ef- fectively manage heat stress.
Test Setup
ecognizing the need for better evaluation methods, it was neces- sary 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 semi- permeable membrane that only allows water vapor to pass, mim- ics 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 re- flects real-world conditions as closely as possible. By simulating actual workplace environments, this testing method provides a
28 Occupational Health & Safety | SEPTEMBER 2024
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