Influence of exposure to summer environments on skin properties

Although cosmetic companies have launched products to combat extreme environments (hot or cold) and various pollutants, research into the effects of these conditions on skin properties is lacking. We aimed to investigate the influence of exposure to outdoor environments during summer on skin properties.

We enrolled 20 women in their 20s and 40s. They were exposed to outdoor and indoor environments for 90 min each in July 2016. Skin evaluations were performed on the face (forehead and cheek) and forearm. Skin hydration level, sebum secretion, trans-epidermal water loss (TEWL), pH and greasiness were evaluated.

Skin hydration levels, sebum secretion, TEWL and greasiness in all examined regions were higher after outdoor exposure than after indoor exposure; however, skin pH decreased after outdoor exposure. Hydration levels on the forearm and sebum secretion on the face increased, whereas hydration levels and TEWL on the cheek, greasiness in all regions except the cheek, and pH in all regions decreased during the 90-min outdoor exposure. The hydration levels in all regions except the cheek, sebum secretion and greasiness on the face increased, but the TEWL and the pH declined after being indoors.

Hot environments cause the production of more sweat, increasing hydration levels, sebum secretion, TEWL, and greasiness and reducing skin pH. After acclimatization, skin hydration on the cheek decreases because of sweat evaporation. Cosmetics that are marketed for use in summer should control sweat and sebum secretion, solve related inconveniences, and provide moisture, especially on the cheeks.