The Effects of Sun Exposure

Exposure to the sun can cause acute and chronic injury to the skin. Sunburn is the visible acute injury, but chronic effects include premature aging, wrinkling of the skin and development of skin cancers including malignant melanoma. Cataract formation has also been implicated in exposure to sun.

Sunburn is caused by overexposure to ultraviolet light including UVA and UVB. UVB causes more skin damage but UVA is up to 100 times more prevalent in the earth's atmosphere. Burning occurs when the amount of exposure to UV light exceeds the ability of the body's protective pigment, melanin, to protect the skin. Light-skinned individuals may burn in less than 15 minutes of noonday exposure, while a dark-skinned person may tolerate the same exposure for hours.

First-degree burns are common and are characterized by red and painful skin within 2-4 hours of sun exposure. More severe, or second-degree burns, cause blistering and swelling of the skin and occasional fever. One blistering sunburn doubles the likelihood that an individual will develop malignant melanoma.

Tanning booths do not prevent the effects of ultraviolet damage to skin. By carefully measuring the amount of ultraviolet exposure they can prevent acute sunburn but they emit UVA light which damages the deeper layers of skin and can predispose an individual to the development of skin cancers and photo aging.