Skin cancer is the most common type of cancer, although most skin cancers are preventable by protecting skin from UV (ultraviolet) radiation. Skin cancer develops when cells are damaged and grow uncontrollably. Exposure to UV rays, from the sun or sunbeds, is the most common cause of skin cancer. UV radiation from the sun is measured using a UV index – this is highest in Ireland between April and September and peaks between 11am and 3pm even on cloudy days. You are at higher risk if you spend a lot of times outdoors, due to your work or leisure activities. It is particularly important to protect the vulnerable skin of babies and young children.