Most skin cancers are caused by excessive UV radiation. Most of this exposure comes from the sun, but some can come from artificial sources, such as As solariums and sun lamps. People who are exposed to UV rays are at higher risk for skin cancer.
The main types of UV rays that can affect your skin are UVA rays and UVB rays. UVB rays can damage the skin and cause skin cancer. There are no safe UV rays.
What influences the UV exposure?
The strength of the sun’s UV rays reaching the ground depends on a number of factors, including:
Time of day: UV rays are strongest in the middle of the day between 10 and 16 o’clock.
Season: In spring and summer the UV rays are stronger. This is less of a factor near the equator.
Distance from the equator (latitude): The UV exposure decreases as you move away from the equator.
Height: At higher altitudes, more UV rays reach the ground.
Cloud cover: The effect of clouds may vary, but it is important to know that UV rays can reach the ground on a cloudy day.
Reflection of Surfaces: UV rays may be reflected off surfaces such as water, sand, snow, or pavement, resulting in increased UV exposure.
The UV index
The US Weather Service and the Environmental Protection Agency (EPA) have developed the UV Index, which gives you an idea of how close the UV light is to a particular day in your area, on a scale of 1 to 11+. A higher number means a higher risk of exposure to UV rays and a higher risk of sunburn and skin damage, which can eventually lead to skin cancer. The UV index is part of many weather forecasts across the country. For more information on the UV Index and your local UV index forecast, visit the EPO website at www.epa.gov/sunsafety/uv-index-1.
Other factors that influence UV exposure
Along with the intensity of the rays, the amount of UV exposure also depends on how long your skin is exposed and whether your skin is protected with clothing or sunscreen.
People living in areas with bright sunlight all year round are at a higher risk for skin cancer. If you spend a lot of time outdoors to work or recover without protective clothing and sunscreen, your risk increases.
The exposure pattern can also affect your skin cancer risk. For example, a common childhood sunburn may increase the risk of some types of skin cancer many years or even decades later.
It is also important to understand that some people are more likely to suffer skin damage from the sun for a variety of reasons.