Physiological Responses to Wearing a Prototype Firefighter Ensemble Compared with a Standard Ensemble

Abstract

This study investigated the physiological responses to wearing a standard firefighter ensemble (SE) and a prototype ensemble (PE) modified from the SE that contained additional features, such as magnetic ring enclosures at the glove-sleeve interface, integrated boot-pant interface, integrated hood-SCBA facepiece interface, and a novel hose arrangement that rerouted self-contained breathing apparatus (SCBA) exhaust gases back into the upper portion of the jacket. Although the features of the PE increased the level of encapsulation of the wearer that could lead to increased physiological stress compared with the SE, it was hypothesized that the rerouted exhaust gases provided by the PE hose assembly would (1) provide convective cooling to the upper torso, (2) reduce the thermal stress experienced by the wearer, and (3) reduce the overall physiological stress imposed by the PE such that it would be either less or not significantly different from the SE. Ten subjects (seven male, three female) performed treadmill exercise in an environmental chamber (22°C, 50% RH) at 50% O_2max while wearing either the SE with an SCBA or the PE with an SCBA either with or without the hose attached (designated PEWH and PENH, respectively). Heart rate (HR), rectal and intestinal temperatures (T_re, T_in), sweat loss, and endurance time were measured. All subjects completed at least 20 min of treadmill exercise during the testing. At the end of exercise, there was no difference in T_re (p = 0.45) or T_in (p = 0.42), HR, or total sweat loss between the SE and either PEWH or PENH (p = 0.59). However, T_sk was greater in PEWH and PENH compared with SE (p < 0.05). Total endurance time in SE was greater than in either PEWH or PENH (p < 0.05). Thus, it was concluded that the rerouting of exhaust gases to the jacket did not provide significant convective cooling or reduce thermal stress compared with the SE under the mild conditions selected, and the data did not support the hypotheses of the present study.

Keywords:

• core body temperature
• firefighter
• heat stress
• skin temperature
• sweat rates

ACKNOWLEDGMENTS

The authors wish to express their gratitude to the Department of Defense Technical Support Working Group (TSWG) and the International Association of Fire Fighters (IAFF) for the funding (in part) and overall project management of this study. The authors also wish to thank Ms. Nicolette Shriver for her technical support of the study and Dr. Jung-Hyun Kim (National Research Council Resident Research Associate) for his contribution to the data analysis and his careful review of the manuscript.

This research was performed while one of the authors, Dr. Aitor Coca, held a National Research Council Resident Research Associateship. Finally, the authors wish to thank the subjects who generously donated their time to participate in this study.

The authors certify that the experimentation conducted on human volunteer subjects described in this study comply with the U.S. Code of Federal Regulations Title 45, Part 46, Protection of Human Subjects (Department of Health and Human Services).

The findings and conclusions of this manuscript are those of the authors and do not necessarily reflect the views of the National Institute for Occupational Safety and Health. Mention of any company name or product does not constitute endorsement by the National Institute for Occupational Safety and Health.