Turnout gear is essential for the safe performance of firefighting duties. Firefighters rely on the protective properties of their turnout gear and should be familiar with the use, care and limitations of that gear. Ironically, the same gear that protects the firefighter also imposes a physiological burden on the firefighter; specifically, the weight and insulative properties of turnout gear contribute to the cardiovascular and thermoregulatory strain experienced by a firefighter. National Fire Protection Association (NFPA) 1971, Standard on Protective Ensembles for Structural Firefighting and Proximity Firefighting, contains material performance requirements for the thermal protective performance (TPP) and total heat loss (THL) that must be provided by the gear.
While fire departments routinely put careful thought into the selection of their turnout gear, much less thought has typically been given to the clothing worn beneath the turnout gear, despite the fact that the station pants/shirt as well as the clothing worn next to the skin, the base layer, contribute to the thermal protection and burden experienced by the firefighter. In addition, the textile properties of the base layer may affect the performance and comfort of the firefighter. The base layer may be considered the foundation of the total protective ensemble that is worn by the firefighter. Thus, it is important to carefully consider the protection provided, the burden imposed, and the comfort of various base layers.
Many firefighters wear a standard cotton T-shirt; however, other materials/textiles have been promoted as being able to better wick sweat away from the body and lower skin temperature compared with 100% cotton T-shirts. These technical textiles are often marketed to athletes, who wear the garments as a single layer, and have recently been introduced to the military and fire service as providing potential benefit.
Several types of technical materials are reported to provide physiological benefits to the wearer under different conditions. Based on previous research, however, it is unclear if these technical materials would provide benefits when worn under turnout gear. Even if technical base layers do not provide an advantage during work cycles in full personal protective equipment (PPE), technical materials have the potential to be of benefit during planned rehabilitation periods of emergency operations when firefighters routinely doff their turnout gear. The purpose of this paper is to describe a research study that investigated differences in protection, physiological impact and comfort among four base layers.
In this research study, we examined the influence of the base-layer material worn under structural turnout gear on physiological and perceptual strain during an alternating work/recovery protocol. The study also incorporated materials performance testing to determine how the inclusion of different base layers with turnout gear affected the performance measures (TPP and THL) required by the NFPA standard. For both types of testing (human performance and materials performance), all layers of clothing worn by the firefighter (base layer and structural turnout gear) were considered as part of an integrated clothing ensemble.
Ten male participants (average age of 21 years) were asked to complete an alternating work/recovery exercise protocol on four separate occasions. On each occasion, participants wore a different base layer material and station pants under firefighting turnout gear. The four base layer materials were chosen for their different properties, including flame resistance for the three technical base layers:
• Cotton – Low cost, user-accepted, comfortable, readily absorbs sweat, may dry slowly
• Modacrylic/rayon synthetic blend – Modacrylic is durable and has excellent fire-resistant properties; rayon adds comfort as well as wicking properties and dries quicker than cotton