Skin cancer. Prolonged exposure to ultraviolet radiation from the sun can lead to melanoma and other skin malignancies. Clear evidence establishes ultraviolet radiation, especially the non-ionizing medium wave UVB, as the cause of most non-melanoma skin cancers, which are the most common forms of cancer in the world
They increase that when they are around smoking because believe it or not the person who is smoking hurts the people around them more then themselves weather they realize it or not they are harming the environment.