What is the difference between UVA and UVB? The sun emits three types of radiation UVA and UVB and UVC. UVA: Accounts for 95% of the radiation that reaches the earth’s surface. This type of radiation can penetrate the skin deeper than UVB and due to its longer wavelength can pass through clouds and glass. It has skin cancer causing potential and also results in premature skin ageing and pigmentation. UVB: These rays cause skin burning and reddening. They do not penetrate the skin as deeply however the majority of skin cancers are due to UVB. UVC: This has the shortest wavelength and is the most damaging type, however it is completely filtered by the atmosphere and therefore does not reach the earth surface. Any easy way to remember is UVA= Ageing and UVB = Burning. However both can cause cancers.