The UV radiation that reaches the Earth consists of UVA and the UVB rays that have not been absorbed in the higher levels in the atmosphere. That matters because of the health effects exposure to this radiation has on the skin, eyes and immune system. UVA rays are the ones that penetrate the skin the deepest, causing the skin to lose its elasticity and to wrinkle, the effects of which are cumulative and delayed by at least 10 years. UVB rays are responsible for the production of melanin (the tan, or the “healthy” glow, which is, in fact, the skin reacting to sun damage and trying to protect itself). You should therefore choose a broad spectrum sunscreen because only broad spectrum sunscreens protect from both UVB and UVA rays, the SPF rating only tells you which percentage of UVB rays a sunscreen blocks.
Exposure to UV radiation can cause skin cancer. The good news is that daily sun protection can reduce this risk and that when diagnosed early (check your skin regularly) it can be treated with a positive outcome. Exposure to sun and especially in environments that include snow, water and sand, apart from being hazardous to our skin, is also dangerous for our eyes. The known effects of radiation exposure, according to the WHO on the eye include inflammation of the parts of the eye, cataracts, cancer of the eye, all of which will require surgical interventions as treatment.