UVA: the deepest penetration
UVA rays penetrate directly into the hypodermis, the deepest layer of the skin. For a long time, they were thought to be harmless because, unlike UVB, they don’t cause sunburn, so there is no discomfort when they penetrate the skin. However, UVA rays are the main culprits of skin ageing because they cause a loss of elastin in skin cells. The skin loses its suppleness, dries out, and wrinkles appear and deepen. UVA rays are also involved in the development of certain skin cancers and melanomas.