Regulating body temperature in warmer months can be challenging under even the most normal circumstances. However, situations requiring flame-resistant (FR) garments can create extra obstacles due to the natural insulation properties of FR clothing. This is why, when developing an FR garment program for hot environments, special considerations must be taken to keep workers as safe and comfortable as possible on the job.
Extreme Heat and the Risk of Heat-Stress
Heat stress commonly is experienced by workers exposed to extreme heat and can result in heat stroke, heat exhaustion, heat cramps or heat rashes, according to the Centers for Disease Control and Prevention. In fact, the U.S. Bureau of Labor Statistics (BLS) reports that "exposure to environmental heat" caused 177 deaths and 13,580 cases of days away from work in the private sector workforce from 2003 to 2008.
Heat stress can be attributed to external factors like temperature, but other factors such as workplace uniforms also can contribute to the impact of these sources of heat. A worker may not consciously realize the effect of his or her garments on core body temperature.
This is why choosing the right clothing is a key factor in regulating temperature while working in a physical role – just like for exercising. The CDC recommends wearing "light-colored, loose-fitting, breathable clothing" to avoid trapping in excess heat. Considering how the company uniform can affect a worker's thermal comfort is essential when evaluating and specifying flame-resistant garments.
Total Heat Loss: The FR Garment Measure You Can't Ignore
A FR garment's total heat loss (THL) rating should be a key consideration when heat stress is a challenge. Most commonly used in the firefighting industry, THL is a method to measure the maximum workload or metabolic activity rate a person can sustain while maintaining thermal comfort in a garment. To classify this, THL measures the amount of conductive (dry) and evaporative (wet) heat loss that occurs through the fabric of a protective garment. In a controlled testing lab, fabric samples are placed on specially designed plates that simulate hot, sweaty skin to precisely measure the heat transferring properties of fabrics. In hot conditions, a fabric that holds less heat is more desirable.
Choosing FR Garments with Hot Environments in Mind
In hot environments, choosing garments with high THL performance is important for employees as well as management. Employees in physical roles may face discomfort, physiological strain, decreased productivity and performance and potentially increased accident rates on the job. A uniform with better performance can impact these challenges.
THL combines the performance of several fabric properties, including air permeability and moisture wicking.
Air permeability is a key contributing factor to good THL performance. Certain garments have a low air permeability rate, which limits evaporation and normal heat dissipation through airflow. This in turn increases body temperature and sweating.
Retaining moisture reduces a fabric's THL rating because it decreases the evaporative cooling capability. So, the same cotton that feels comfortable around the house becomes a liability in an extremely hot work environment. For example, cotton shirts are soft and comfortable in moderate temperatures, but when exposed to increased levels of sweat, they become saturated and will be less comfortable.
FR chemical treatment can impact air permeability and moisture management as well.
The natural reaction to facing a hot environment in heavy clothing is to make modifications to the garments, affecting their intended purpose. Rolling up sleeves or leaving a coverall unzipped are common modifications that unravel FR safety protocols, and in some cases may add the risk of entanglements.
Taking Steps to Keep Workers Safe
By selecting FR garments with THL measures in mind, safety managers can take steps to ensure employees will remain safe and comfortable in the workplace. In addition to preventing accidents, selecting the right FR garment can help increase productivity as workers may require fewer, shorter breaks and less time off related to heat stress issues.
Lowering heat stress should be considered an important part of managing safety in a warmer workplace. By specifying garments that are lightweight, breathable and moisture-wicking, safety managers can help prevent heat-related accidents and injuries.
In addition to specifying optimal garments for hot environments, safety managers should take the initiative to educate employees on selecting the right garments, should they provide their own. Safety managers and employees also should be aware of the risks of overheating on the job. OSHA suggests providing information on the "health effects of heat, the symptoms of heat illness, how and when to respond to symptoms, and how to prevent illness."
Each garment should be assessed not only in terms of breathability, but moisture-wicking ability and weight as well. Finally, safety managers and employees should be well-educated on the risks of overheating on the job.
Cortlandt Minnich is the new business development director for TECGEN FR at INVISTA.