Solar radiation includes, of course, visible light. UV radiation at high doses increases the risk of basal cell carcinoma and malignant melanoma . Mild sunburn is a first-degree radiation burn. In a mild sunburn, the skin is red and painful. The outer layers of the epidermis peel in 3-6 days, with itching and redness persisting up to a week or more.
Extreme sunburn can also be a second-degree burn.
Third-degree sunburn is rare, and likely requires several days of exposure. The first commercial sunscreen was developed in 1928, and contained benzyl salicylate and benzyl cinnamate . Many early products were focused on UVB, the portion of the light spectra that causes the familiar sunburn. Much newer micronized or microfine metallic oxide reflecting powders provide broad-spectrum protection against UVA and UVB radiation. Antioxidants are also being included in sunscreens as free-radical scavengers.