Understanding the basics about UV radiation and how it damages your skin is an important first step in learning how to safeguard yourself against skin cancer. 

Exposure to sun causes most of the Wrinkles and Age Spots on our faces and bodies. When it comes to Skin Cancer, a major Risk Factor is prolonged exposure to Ultraviolet (UV) Radiation.

The good news is that the danger posed by UV radiation can be greatly reduced by you! Yes, you can still enjoy outdoor activities while limiting your skin cancer risk by taking simple, smart protective measures.

What is ultraviolet radiation

What Is UV (Ultraviolet Radiation)
  • Ultraviolet is a form of electromagnetic radiation with wavelength from 10 to 400 nm, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight, and constitutes about 10% of the total electromagnetic radiation output from the Sun
  • UV light has shorter wavelengths than visible light, so your eyes can’t see UV, but your skin can feel it
  • Tanning beds and lamps are also sources of UV rays

What UV radiation does?

How UV Affects You 
  • Unprotected exposure to UV rays damages the DNA in skin cells, producing genetic defects, or mutations, that can lead to skin cancer (as well as premature aging.)
  • These rays can also cause eye damage, including cataracts and eyelid cancers
  • Damage from UV exposure is cumulative and increases your skin cancer risk over time
  • While your body can repair some of the DNA damage in skin cells, it can’t repair all of it. The unrepaired damage builds up over time and triggers mutations that cause skin cells to multiply rapidly. That can lead to malignant tumors
  • The degree of damage depends on the intensity of UV rays and the length of time your skin has been exposed without protection

    Types of Ultraviolet Radiation

    Types of Ultraviolet Radiation
    • There are three types of UV radiation
    • UVA
    • UVB
    • UVC

    Damaging UVA Effects

    Damaging Effects of UVA Radiation
    • UVA rays cause tanning, and the shorter wavelengths of UVA also cause sunburn
    • There is no such thing as a safe or healthy tan.
    • UVA radiation is proven to contribute to the development of skin cancer
    • UVA is connected to the “broad-spectrum protection” you see on the labels of sunscreen products
    • Early sunscreens only protected your skin from UVB rays, but once it was understood how dangerous UVA rays were, sunscreen manufacturers began adding ingredients to protect you from both UVB and UVA across this broader spectrum.
    • UVA rays, while slightly less intense than UVB, penetrate your skin more deeply. Exposure causes genetic damage to cells on the innermost part of your top layer of skin, where most skin cancers occur. The skin tries to prevent further damage by darkening, resulting in a tan
    • Over time, UVA also leads to premature aging and skin cancer.
    • UVA radiation is the main type of light used in most tanning beds. Once thought to be safe, we now know it is just the opposite
    • UVA is everywhere. UVA accounts for up to 95 percent of the UV radiation reaching the earth.
    • These rays maintain the same level of strength during daylight hours throughout the year. This means that during a lifetime, we are all exposed to a high level of UVA rays
    • UVA can penetrate windows and cloud cover

    Damaging UVB Effects

    Damaging Effects of UVB Radiation
    • UVB penetrates and damages the outermost layers of your skin Overexposure causes suntan, sunburn and, in severe cases, blistering
    • UVB is connected to the Sun Protection Factor (SPF) on labels of sunscreen products.
    • The SPF number tells you how long the sun’s radiation (including some of the UVA) would take to redden your skin when using that product compared to the time without sunscreen.
    • UVB intensity fluctuates. While the sun’s rays are strongest and pose the highest risk late-morning to mid-afternoon from spring to fall in temperate climates and even greater timespans in tropical climates
    • UVB rays can damage your skin year-round, especially at high altitudes or on reflective surfaces like snow or ice.
    • UVB rays can be filtered and do not penetrate glass

    UVC Rays

    And What About UVC?
    • UVC is the shortest wavelength of the three forms of UV.

    • The shorter the wavelength, the more harmful the UV radiation. However, lucky for us, UVC isn't able to penetrate earth's atmosphere.

    • So while UVC is the most dangerous it's not a risk to the typical person because the sun's natural UVC emissions don't penetrate  earth's atmosphere naturally at all

    • UVC is absorbed completely by the ozone layer.


    • This is not to say that UVC isn't dangerous. Although naturally occurring UVC doesn't permeate earth's atmosphere, inorganic sources of UVC radiation exist and are dangerous when not used properly.

    • The people who need to be concerned about UVC radiation are those working with these man-made sources of UVC, like welding torches and mercury lamps among others 

    Time of Day

    Time of The Day
    • UV rays are strongest in the middle of the day, between 10 am and 4 pm

    Season Of the year

    Season Of The Year
    •  UV rays are stronger during spring and summer months. This is less of a factor near the equator

    Distance from the Ecuator

    Distance From The Ecuator (Latitude)
    •  UV exposure goes down as you get further from the equator


    • More UV rays reach the ground at higher elevations

    Cloud Cover

    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

    Reflection on surfaces

    Reflection Off Surfaces
    • UV rays can bounce off surfaces like water, sand, snow, or pavement, leading to an increase in UV exposure
    The UV Index

     As noted above, the amount of light reaching the ground in any given place depends on a number of factors. To help the people better understand the strength of UV light in their area on any given day, The National Weather Service and The Environmental Protection Agency (EPA) have developed the UV Index. 

    The UV Index gives people an idea of how strong the UV light is in their area on a scale from 1 to 11+. A higher number means greater risk of exposure to UV rays and a higher chance of sunburn and skin damage that could ultimately lead to skin cancer,

    The UV Index is given daily for regions throughout the country. Further information about about the UV Index can be found on the EPA's website