UVA rays cause skin aging and wrinkling and contribute to skin cancer, such as melanoma. Because UVA rays pass through the ozone layer, they make up the majority of our sun exposure. Beware of tanning beds because they use UVA rays.

UVB rays are also dangerous, causing sunburns, cataracts (clouding of the eye lens), and immune system damage. They also contribute to skin cancer. Melanoma, the most dangerous form of skin cancer, is thought to be associated with severe UVB sunburns that occur before the age of 20. Most UVB rays are absorbed by the ozone layer, but enough of these rays pass through to cause serious damage.