Rapid Skin Responses to a Low Humidity Environment and the Benefits of a Fine Fiber Film
Junko Ishikawa, Akane Kawamoto, Urara Yokose, Noriyasu Ota, Takatoshi MuraseABSTRACT
Background
A short single low‐humidity stay (SSLHS) induces rapid changes in stratum corneum (SC) function, but their significance and inter‐individual variability remain unclear. We examined associations between baseline SC function and rapid SSLHS responses and evaluated whether a lotion‐free fine fiber (FF) film modulates these responses.
Materials and Methods
Forty healthy Japanese women ( n = 40) completed 6‐h stays at 60% RH and, on the next day, 20% RH (23°C). TEWL, capacitance, and skin texture were measured on the open cheek at 0, 3, and 6 h. During SSLHS, an FF film was applied to the right half of the face and assessed at 0 and 6 h. Pearson's r and within‐subject differences in absolute change (absΔ; FF − open) are reported with 95% confidence intervals (95%CI).
Results
TEWL decreased under both RH conditions, whereas capacitance increased only at 60% RH. Under SSLHS, absΔTEWL (3 h–0 h) was associated with baseline TEWL ( r = 0.661, 95%CI 0.44–0.81), capacitance ( r = −0.504, 95%CI −0.70 to −0.23), and SEr ( r = 0.518, 95%CI 0.25–0.71). During SSLHS, the FF film reduced absΔTEWL (mean difference −1.22 [95%CI −2.36, −0.09]) and increased absΔCapacitance (+2.20 [0.87, 3.54]) versus the open side. Exploratory subgroup analysis suggested larger differences in subjects classified as sensitive.
Conclusion
Rapid low‐humidity responses vary with baseline SC function, and an FF film without lotion modulates short‐term responses to low humidity.