068 The skin is greatly influenced by the external environment in summer

Abstract

The skin is greatly influenced by the seasonal climate changes, resulting in dry skin in winter and oily skin in summer. However, there have been few studies that investigated the changes in skin directly exposed to the external environment in summer and winter. The purpose of this study was to explore the effects of hot temperature and high humidity on the skin in summer, by comparing the changes in skin parameters of subjects after the exposure to indoor and outdoor environments in summer. We recruited 20 Korean women aged 25-40 years in July. They washed the face and the ventral forearm with cleansing soap and were adapted for 20 minutes in an air-conditioned indoor environment and an outdoor environment where the direct sunlight is blocked. The skin parameters including the skin hydration, TEWL, pH and sebum were measured under each environment using non-invasive instruments. After exposure to an external environment for 20 minutes, the skin parameters were significantly changed in the forehead, cheek, and forearm, compared to the skin parameters accustomed to the indoor condition. The most significantly affected skin parameter in an external environment was TEWL with about twofold increase in forearm and forehead. The skin pH values and sebum levels were most significantly changed in the forehead, while TEWL and hydration levels were affected most in the forearm. A brief exposure to a hot and humid environment in summer dramatically affected the skin parameters. In a hot climate, the amount of perspiration increases along with secretion of lactic acid in the sweat gland. These phenomena contributed to the decreased skin pH level while the skin hydration and TEWL levels were elevated. The sebum levels also increased especially on the forehead, where many pores are distributed. Also, the subjects were dissatisfied with their skin conditions in the outdoor environment. Therefore it is necessary to formulate the cosmetics considering seasonal climate variation.