What makes ultraviolet rays harmful

Seek shade from 11 a. Cover up with a wide-brimmed hat and wear loose-fitting, light-coloured, tightly-woven clothing. Wear sunglasses that block 99 to percent of UV radiation.

Apply broad-spectrum lip balm and sunscreen on any exposed skin, even when it's cloudy. Use SPF 30 or higher. Reapply every two hours, or after working, swimming, playing or exercising outdoors. Top of the page Next Section: Related Information. Previous Section: Related Information Top of the page.

While it has some benefits for people, including the creation of Vitamin D, it also can cause health risks. Even though UVA radiation is weaker than UVB, it penetrates deeper into the skin and is more constant throughout the year.

Beneficial effects of UV radiation include the production of vitamin D, a vitamin essential to human health. Vitamin D helps the body absorb calcium and phosphorus from food and assists bone development. This Web page provides an overview of the major health problems linked to overexposure to UV radiation.

Understanding these risks and taking sensible precautions will help you enjoy the sun while reducing your chances of sun-related health problems. Each year, more new cases of skin cancer are diagnosed in the U. One in five Americans will develop skin cancer in their lifetime. One American dies from skin cancer every hour. Unprotected exposure to UV radiation is the most preventable risk factor for skin cancer.

Melanoma, the most serious form of skin cancer, is now one of the most common cancers among adolescents and young adults ages While melanoma accounts for about three percent of skin cancer cases, it causes more than 75 percent of skin cancer deaths. UV exposure and sunburns, particularly during childhood, are risk factors for the disease. Not all melanomas are exclusively sun-related—other possible influences include genetic factors and immune system deficiencies.

Non-melanoma skin cancers are less deadly than melanomas. Nevertheless, they can spread if left untreated, causing disfigurement and more serious health problems. There are two primary types of non-melanoma skin cancers: basal cell and squamous cell carcinomas. If caught and treated early, these two cancers are rarely fatal. Other UV-related skin disorders include actinic keratoses and premature aging of the skin.

UV rays are in the middle of this spectrum. They have more energy than visible light, but not as much as x-rays. There are also different types of UV rays, based on how much energy they have.

Higher-energy UV rays are a form of ionizing radiation. This means they have enough energy to remove an electron from ionize an atom or molecule.

Ionizing radiation can damage the DNA genes in cells, which in turn may lead to cancer. Different types of UV rays reach the ground in different amounts. The amount of UV exposure a person gets depends on the strength of the rays, the length of time the skin is exposed, and whether the skin is protected with clothing or sunscreen. Most skin cancers are a result of exposure to the UV rays in sunlight. Both basal cell and squamous cell cancers the most common types of skin cancer tend to be found on sun-exposed parts of the body, and their occurrence is typically related to lifetime sun exposure.