Another reaction of interaction with the sun is keratinization—the skin cells on the surface hardening. Dead skin cells do not exfoliate and prevent the release of sebum from the pores.
It also increases sweating. Sweat and grease come to the surface and improve the breeding ground for bacteria. It is no coincidence that in the summer, the appearance of acne increases.
The UV rays dry and thin the skin. The body reacts and produces more sebum to compensate for the loss.