Effect of room humidity on the formation of fine wrinkles in the facial skin of Japanese

Background/purpose: Changes in humidity are commonly known to influence the condition of the skin. Previous studies of the skin dealt with variations in relative humidity (RH) either through statistical analysis or by maintaining room humidity at a constant level; however, the range of humidity and the length of acclimation varied in each study. This study aimed to determine whether the generally used ranges of RH are truly acceptable for studies of human skin. Methods: Skin conductance, elasticity and fine wrinkles were assessed on the eyelids of 20 volunteers, first after acclimation for 30 min in a high-humidity room (70% RH) and again after acclimation for 30 min in a low-humidity room (40% RH). Results: The study found significant decreases in skin conductance and elasticity and significant increases in fine wrinkles after acclimation to low humidity compared with high humidity. Conclusion: These results indicate that even a 30% difference in RH can affect skin properties in 30 min. The importance of humidity stabilization and the necessity of acclimation to the humidity, particularly when the study concerns wrinkles, were thus confirmed.