Overexposure to UV rays is a major risk factor for skin cancers and cataracts. Humans on Earth are exposed to UV radiation of various wavelengths, which can be subdivided in: UVA (320 to 400 nm) and UVB (290 to 320 nm). UVA rays are not absorbed by the ozone layer, while about 98% of UVB rays normally are. UVB rays have more energy, are the main rays that cause sunburns, and are thought to cause most skin cancers.
Show More »« Show Less