The earth's atmosphere absorbs UVC wavelengths. UVA rays cause aging, wrinkling, and loss of elasticity. UVA also increases the damaging effects of UVB, including skin cancer and cataracts. People with fair skin , with a northern European heritage seem to be most susceptible. Due to a reduction of ozone in the earth's atmosphere, the level of UV light today is higher than it was 50 or 100 years ago.
Ozone serves as a filter to screen out and reduce the amount of UV light.
With less atmospheric ozone, a higher level of UV light reaches the earth's surface. They are quite easily detected and may be successful treatment by excisional biopsy. However, non-melanoma skin cancer places people at high risk for developing additional skin cancers. Basal cell carcinoma accounts for more than 90 percent of all skin cancers in the United States. It is a slow-growing cancer that seldom spreads to other parts of the body.