title: The effect of air permeability characteristics of protective garments on the induced physiological strain under exercise-heat stress.
abstract: OBJECTIVE
  The high values of thermal resistance (Rct) and/or vapor resistance (Ret) of chemical protective clothing (CPC) induce a considerable thermal stress. The present study compared the physiological strain induced by CPCs and evaluates the relative importance of the fabrics' Rct, Ret, and air permeability in determining heat strain.
  
  
  METHODS
  Twelve young (20-30 years) healthy, heat-acclimated male subjects were exposed fully encapsulated for 3h daily to an exercise-heat stress (35°C and 30% relative humidity, walking on a motor-driven treadmill at a pace of 5 km h(1) and a 4% inclination, in a work-rest cycle of 45 min work and 15 min rest). Two bipack CPCs (PC1 and PC2) were tested and the results were compared with those attained by two control suits-a standard cotton military BDU (CO1) and an impermeable material suit (CO2).
  
  
  RESULTS
  The physiological burden imposed by the two bilayer garments was within the boundaries set by the control conditions. Overall, PC2 induced a lower strain, which was closer to CO1, whereas PC1 was closer to CO2. Air permeability of the PC2 cloth was almost three times higher than that of PC1, enabling a better heat dissipation and consequently a lower physiological strain. Furthermore, air permeability characteristic of the fabrics, which is associated with its construction and weave, significantly correlated with the physiological strain, whereas the correlation with Rct, Ret, and weight was poor.
  
  
  CONCLUSIONS
  The results emphasize the importance of air permeability in reducing the physiological strain induced by CPCs.
authors: Heller Institute of Medical Research, Sheba Medical Center, Tel Hashomer, Israel. Yoram.epstein@sheba.health.gov.il
authors: Yoram
authors: Y
authors: Epstein
authors: Yuval
authors: Y
authors: Heled
authors: Itay
authors: I
authors: Ketko
authors: Jeni
authors: J
authors: Muginshtein
authors: Ran
authors: R
authors: Yanovich
authors: Amit
authors: A
authors: Druyan
authors: Daniel S
authors: DS
authors: Moran
mesh_terms: D000328:Adult; D001831:Body Temperature / Q000502:physiology; D015444:Exercise; D006339:Heart Rate / Q000502:physiology; D018882:Heat Stress Disorders / Q000503:physiopathology / Q000517:prevention & control*; D006801:Humans; D008297:Male; D008422:Materials Testing / Q000379:methods; D010539:Permeability; D016062:Porosity; D011481:Protective Clothing / Q000009:adverse effects / Q000592:standards*; D012881:Skin Temperature / Q000502:physiology; D013312:Stress, Physiological / Q000502:physiology*; D013546:Sweating / Q000502:physiology; D055815:Young Adult
keywords: heat strain; heat stress; protective garments; thermal resistance; water vapor resistance