title: Water nanodroplets make a greater contribution to facial skin moisture levels in air-conditioned rooms during winter than in summer.
abstract: OBJECTIVE
  By performing experiments in air-conditioned chamber, we previously demonstrated that the presence of water nanodroplets (mist) improved facial skin moisture levels without reducing water loss from the facial skin surface or inducing excessive humidity. Some previous studies have demonstrated that the epidermis is a less effective barrier to water in winter because the corneocytes that comprise facial skin become smaller in winter as skin turnover increases in cold environments. We hypothesized that it would be easier for mist to penetrate into the facial stratum corneum (SC) in winter than in summer. In the present study, we investigated the ability of mist to improve facial skin moisture levels in winter and summer.
  
  
  METHODS
  We examined transepidermal water loss (TEWL) as an index of barrier function and skin conductance as an index of SC hydration at the forehead, lateral canthus, and cheeks in eight healthy Japanese females (mean ± SD: 45.5 ± 3.2 years) in the presence or absence of mist in February-March and July.
  
  
  RESULTS
  In the absence of mist, skin conductance at the forehead and lateral canthus was significantly higher in summer than in winter, but these seasonal differences were diminished in the presence of mist. In the presence of mist, skin conductance was increased in winter and decreased in summer at the lateral canthus; however, these changes were not significant. Thus, our findings suggest that mist penetrates into the SC and improves skin moisture levels in winter.
  
  
  CONCLUSIONS
  We demonstrated that it is easier for mist to penetrate into the SC at the lateral canthus during winter than in summer. Thus, mist is expected to improve facial moisture levels in winter by penetrating into and remaining in the SC. Hence, mist could be used to help prevent facial skin from becoming dry in air-conditioned rooms during winter.
authors.affiliation: The Department of Physiology, School of Medicine, Aichi Medical University, Nagakute, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Ohno
authors.forename: N
authors.initials: N
authors.lastname: Nishimura
authors.forename: K
authors.initials: K
authors.lastname: Yamada
authors.forename: Y
authors.initials: Y
authors.lastname: Shimizu
authors.forename: R
authors.initials: R
authors.lastname: Nishimura
authors.forename: S
authors.initials: S
authors.lastname: Iwase
authors.forename: J
authors.initials: J
authors.lastname: Sugenoya
authors.forename: M
authors.initials: M
authors.lastname: Sato
mesh_terms: D000328:Adult; D000389:Air Conditioning / Q000379:methods*; D001834:Body Water / Q000737:chemistry*; D005145:Face; D005260:Female; D006801:Humans; D006813:Humidity; D008875:Middle Aged; D053758:Nanoparticles / Q000737:chemistry; D012621:Seasons; D012867:Skin / Q000737:chemistry*; D012869:Skin Absorption; D014867:Water / Q000737:chemistry*; D014870:Water Loss, Insensible
chemical_list: D014867:Water
keywords: biophysical parameter; hydration; mist; skin; water nanodroplets; winter