What type of UV radiation is primarily responsible for skin aging?

UVA radiation is primarily responsible for skin aging due to its ability to penetrate deep into the skin layers, particularly the dermis, where it can damage collagen and elastin fibers. This damage disrupts the skin's structural integrity, leading to wrinkles and a loss of elasticity, which are hallmark signs of aging. Furthermore, UVA radiation contributes to the formation of free radicals, which can also accelerate the aging process of the skin by breaking down cellular components.

UVB radiation, while responsible for sunburn and some skin cancers, has a more superficial effect on the skin, primarily impacting the epidermis. UVC radiation is mostly absorbed by the Earth's atmosphere and does not reach the skin, making it less relevant concerning direct skin effects. Visible light radiation is not classified as ultraviolet and does not significantly contribute to skin aging in the same manner as UVA radiation does. Thus, the focus on UVA as the main contributor to skin aging highlights its unique properties and the need for protective measures against it.