Skin characteristics following repeated exposure to simulated outdoor and indoor summer temperatures in South Korea and Southeast Asia.

BACKGROUND Although changes in skin depend on the external environment, researchers have performed only a few studies on effect of the actual environment. Most studies have researched skin characterization based on changes in the humidity or temperature. AIM/OBJECTIVE This study aimed to evaluate changes in the skin based on the difference in indoor and outdoor temperatures and humidity during summer in South Korea and Southeast Asia. METHODS Twenty-two female participants aged 25-39 years were included. Skin hydration, sebum (cheek, forehead), color, transparency, and pores of the participants were measured after a 30-min exposure to high temperature and high humidity (HTHH) environment and a 30-min exposure to low temperature and low humidity (LTLH) environment. Subsequently, exposure to HTHH environment for 30 min + LTLH environment for 30 min was performed after a total of 1 h and repeated. RESULTS Repeated exposure to HTHH and LTLH environments increased the skin's sebum content and hemoglobin index. Additionally, skin elasticity was significantly reduced, with patients in their 30s showing greater changes than those in their 20s. CONCLUSION Repeated differences in temperature and humidity cause skin aging, loosen skin vessels, and reduce skin elasticity, thereby leading to skin aging.