What Factors Affect UV Risk?
The main types of UV rays that can affect your skin include UVA rays and UVB rays. UVB rays have more energy and are a more potent cause of at least some skin cancers, but both UVA and UVB rays can damage skin and cause skin cancer. There are no safe UV rays.
Everyone’s skin reacts differently to UV (ultraviolet) rays, but anyone can get skin cancer. Most skin cancers are caused by too much exposure to UV rays, mostly from the sun, but from artificial sources, such as indoor tanning beds and sun lamps. People who get a lot of exposure to UV rays are at greater risk for skin cancer, so it’s important to understand what affects how much UV you are exposed to and how your skin might respond.
What affects the strength of UV rays from the sun?
The strength of the sun’s UV rays reaching the ground depends on a number of factors, such as:
- Time of day: UV rays are strongest in the middle of the day, between 10 am and 4 pm.
- Season of the year: UV rays are stronger during spring and summer months, and in early fall. This is less of a factor near the equator.
- Distance from the equator (latitude): UV strength and exposure goes down as you get further from the equator. People who live in areas with year-round, bright sunlight have a higher risk of skin cancer.
- Altitude: More UV rays reach the ground at higher elevations.
- Cloud cover: The effect of clouds can vary, but it's important to know that UV rays can get through to the ground, even on a cloudy day and even on a cold day.
- Reflection off surfaces: UV ray