Seasonal variations of epidermal biophysical properties in Kunming, China: A self-controlled cohort study

Epidermal biophysical properties can be affected by many factors, including body site, age, gender, ethnicity, disease, temperature, humidity, and ultraviolet (UV) radiation. Information about variation of epidermal biophysical properties with seasons is still limited. In the present study, we determined seasonal variation of epidermal biophysical properties of women in Kunming, China.A total of 72 women, aged 22.96 ± 2.11 years, were enrolled in this study. Transepidermal water loss rates (TEWL), stratum corneum (SC) hydration, sebum content, melanin index (MI), erythema index (EI), and L*a* values were measured on the right cheek and the right forearm, using a non-invasive skin physiological instrument in the spring, summer, autumn, and winter in Kunming, China.On the cheek, TEWL, SC hydration, sebum, MI, and L*a* values varied greatly with seasons (P .05). SC hydration, sebum, MI, and a*value peaked in the summer, but went lowest in winter. In contrast, TEWL and L*value went lowest in summer but peaked in winter. Similarly, SC hydration, MI, and L*value also varied with seasons on the forearm (P .05). In addition, SC hydration, sebum, MI, EI, and a*value of the cheek were higher than that of the forearm (P .001), but L*values of the cheek were lower than that of the forearm (P .001). There were no correlations among TEWL and MI, EI, and L*a*values in any season (P .05).Both epidermal permeability barrier function, sebum, and skin pigment in healthy women vary seasons in Kunming, China.