A method to reduce heat strain while clad in encapsulating outerwear

Abstract

The use of personal protective equipment (PPE) increases the risk of heat related maladies. A means to enhance heat dissipation capacity of individuals clad in PPE would be of benefit. The glabrous skin regions of the hands, face, and feet are portals for direct heat transfer between the body core and the external environment. The effects of PPE outerwear and palmar glabrous skin cooling on heat storage were assessed. Subjects engaged in fixed load treadmill exercise in a thermoneutral environment (T_a = 20–24°C) or rested in a hot environment (45 ± 0.5°C). The use of PPE outerwear increased the rate of core temperature rise by five-fold during vigorous exercise. Palm cooling using a stationary water circulation system attenuated the rate of core temperature rise by 30–60% during rest and light, moderate, and vigorous exercise while wearing PPE outerwear. However, the subjects were tethered to the system. A wearable cooling system was devised that allowed free range of motion and unrestricted mobility. The wearable system provided thermal benefits equivalent to the use of the tethering cooling system. With optimization, this wearable cooling technique could neutralize the negative thermoregulatory effects of wearing PPE while engaged in light workload activities such as those encountered by healthcare professionals working in infectious disease treatment centers. For individuals working at higher workloads, such as firefighters, a wearable glabrous skin-based cooling system could extend work bout duration as well as enhance heat loss during episodic recovery periods.

Keywords:

• Core temperature
• heat illness
• hyperthermia
• protective clothing
• temperature
• work/rest cycles

Acknowledgments

The authors acknowledge and appreciate the support of Vinh Cao and Patricia Seawell for the execution of the protocols as well as the undergraduate students who participated in the studies. Our thanks to DuPont and Camelbak Products for generously supplying the PPE overalls and the hydration packs (respectively). No external funding supported these studies.