Physiological strain of next generation combat uniforms with chemical and biological protection: importance of clothing vents

Abstract

This study examined whether vents in the arms, legs and chest of new protective assault uniforms (PTAU) reduced heat strain at 35°C during a low dressed state (DS_low), and subsequently improved tolerance time (TT) after transitioning to DS_high compared with the battle dress uniform and overgarment (BDU+O). Small but significant reductions in rectal temperature (T _re), heart rate and vapour pressures over the thigh and shin were observed during DS_low with vents open (37.9 ± 0.2°C, 120 ± 10 b/min, 3.7 ± 0.4 and 3.5 ± 1.0 kPa) versus closed (38.0 ± 0.1°C, 127 ± 5 b/min, 4.3 ± 0.3 and 4.6 ± 0.5 kPa). During DS_high T _re was reduced and TT increased significantly with the PTAUs (1.1 ± 0.2°C/h and 46 ± 24 min) versus BDU+O (1.6 ± 0.2°C/h and 33 ± 16 min). The vents marginally reduced heat strain during DS_low and extended TT during DS_high compared with BDU+O.

Practitioner Summary: Clothing vents in chemical and biological protective uniforms can assist with heat transfer in situations where the uniforms must be worn for extended periods prior to exposure to a hazardous condition. Once the vents are closed, exposure time is increased and the increase in body temperature reduced.

Keywords:

• uncompensable heat stress
• core temperature
• wind
• evaporative heat loss

Acknowledgements

The authors are indebted to the participants for committing their time and effort for this project. Also, the technical assistance of Mrs. Debbie Kerrigan-Brown, Mr. Doug Saunders, Capt. Lori Coady, Capt. Tony Maurais, Capt. Erin Smith, Lt. Olivier Larouche and Lt. Gordon Pajuluoma is gratefully acknowledged. This study was conducted in accordance with Canadian TriCouncil Policy Statement on ethics in human research. The authors declare that they have no conflict of interest.