title: A study of the behavior and mechanism of thermal conduction in the skin under moist and dry heat conditions.
abstract: OBJECTIVE
  We analyzed skin heat conduction under moist and dry heat conditions to confirm the influence of moist heat on the skin and subcutaneous region.
  
  
  METHODS
  Six healthy subjects placed their forearms in moist and dry heat air chambers, and the thickness of and moisture levels in the stratum corneum were measured. Skin surface temperatures, heat flux, and skin blood flow were measured in 11 healthy subjects.
  
  
  RESULTS
  Within 10 min, the stratum corneum in skin exposed to moist heat reached a thickness of about 150%, and water content in the stratum corneum increased to about 200%. In contrast, the thickness of water content in the stratum corneum did not change in the dry heat condition. Skin surface temperatures of skin exposed to moist heat were significantly higher after 0.5 min of exposure (P < 0.01), the skin surface heat flux was greater, and blood flow was significantly higher (P < 0.05) after 10 min than that of skin exposed to dry heat.
  
  
  CONCLUSIONS
  Stratum corneum moisture levels and skin surface heat conductivity were higher in the moist heat condition and skin blood flow was significantly greater than that in skin exposed to dry heat. Therefore, moist heat is more efficient at warming the body than dry heat.
authors.affiliation: Personal Health Care Products Research Laboratories, Kao Corporation, Tokyo, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Igaki
authors.forename: T
authors.initials: T
authors.lastname: Higashi
authors.forename: S
authors.initials: S
authors.lastname: Hamamoto
authors.forename: S
authors.initials: S
authors.lastname: Kodama
authors.forename: S
authors.initials: S
authors.lastname: Naito
authors.forename: S
authors.initials: S
authors.lastname: Tokuhara
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology; D001833:Body Temperature Regulation / Q000502:physiology*; D001834:Body Water / Q000502:physiology*; D004735:Energy Transfer / Q000502:physiology; D005260:Female; D006361:Heating / Q000379:methods*; D006801:Humans; D006813:Humidity; D008297:Male; D012867:Skin / Q000098:blood supply; D012881:Skin Temperature / Q000502:physiology*; D013227:Steam; D013814:Thermal Conductivity; D055815:Young Adult
chemical_list: D013227:Steam
keywords: blood flow; heat flux; moisture; stratum corneum; thermal resistance