Ultraviolet Radiation

Image of sun in blue sky

Radiation can naturally come from the sun through ultraviolet (UV) radiation

Ultraviolet (UV) radiation is a form of non-ionizing radiation that is emitted by the sun and artificial sources, such as tanning beds. The beneficial effects of UV radiation include the production of a vital nutrient, vitamin D; however, overexposure may present risks. Sunburn, premature aging, and skin cancer are all risks to overexposure. Keeping you and others protected from UV radiation is an important, year-round responsibility.

What are sources of UV radiation?

  • Our natural source includes:
    • The sun
  • Some artificial sources include:
    • Tanning Beds
    • Mercury vapor lighting (often found in stadiums and school gyms)
    • Some halogen, fluorescent, and incandescent lights
    • Some types of lasers

UV radiation is classified into one of three primary groups: ultraviolet A (UVA), ultraviolet B (UVB) and ultraviolet C (UVC). This grouping is based on the measure of their wavelength, which is measured in nanometers (nm= 0.000000001 meters or 1×10-9 meters).

UV Radiation
Wavelength 315-399 nm 280-314 nm 100-279 nm
Absorption Level Not absorbed by the ozone layer Mostly absorbed by the ozone layer, but some does reach the Earth’s surface Completely absorbed by the ozone layer and atmosphere

All of the UVC and most of the UVB radiation is absorbed by the earth’s ozone layer, so nearly all of the ultraviolet radiation received on Earth is UVA.  Even though UVA radiation is weaker than UVB, it penetrates deeper into the skin and is more constant throughout the year.  Since UVC radiation is absorbed by the earth’s ozone layer, it does not pose as much of a risk.


  • Beneficial effects of UV radiation include the production of vitamin D, a vitamin essential to human health.  Vitamin D helps the body to absorb calcium and phosphorus from food and assists in bone development.  The World Health Organization (WHO) recommends 5 to 15 minutes of sun exposure 2 to 3 times a week.  Additional information can be found here.
  • Artificial forms of UV radiation (lasers, lamps, or a combination of these devices) used with some topical medications that increase UV sensitivity are sometimes used to treat patients with certain diseases who have not responded to other methods of therapy.  A trained healthcare professional uses this special procedure called phototherapy to treat the following:
    • Rickets
    • Psoriasis
    • Eczema
    • Vitiligo
    • Lupus



  • Sunburn is a sign of short-term overexposure, while premature aging and skin cancer are side effects of prolonged UV exposure.
  • Some oral and topical medicines, such as antibiotics, birth control pills, and benzoyl peroxide products, as well as some cosmetics, may increase skin and eye sensitivity to UV in all skin types.
  • UV exposure increases the risk of potentially blinding eye diseases, if eye protection is not used.
  • Overexposure to UV radiation can lead to serious health issues, including cancer.  Skin cancer is the most common cancer in the United States.  The two most common types of skin cancer are basal cell cancer and squamous cell cancer. Typically, they usually form on the head, face, neck, hands, and arms because these body parts are the most exposed to UV radiation.  Most cases of melanoma, the deadliest kind of skin cancer, are caused by exposure to UV radiation.


Anyone can get skin cancer, but is more common in people who:

  • Spend a lot of time in the sun or have been sunburned
  • Have light-color skin, hair and eyes
  • Have a family member with skin cancer
  • Are over age 50

Changes in your skin are the most common signs of skin cancer. To learn more about the symptoms of skin cancer, please click the link found here.

Keeping yourself and others protected from UV radiation is an important, year-round responsibility, not just at the beach or during the summer months.  To protect yourself from UV radiation:

  • Stay in the shade, especially during midday hours.
  • Wear clothes that cover your arms and legs.
  • Wear a hat with a wide brim to shade your face, head, ears, and neck.
  • Wear sunglasses that wrap around and block both UVA and UVB rays.
  • Use sunscreen with sun protection factor (SPF) 15 or higher, and both UVA and UVB protection.

The UV Index scale helps us understand how harmful UV radiation can be on a given day. This useful tool forecasts the strength of the sun’s harmful rays. Remember, the higher the number, the greater chance of overexposure leading to health concerns.

Related Links

Basic Information about Skin Cancer

This web site provides basic information about the health effects of ultraviolet radiation and the difference between UVA, UVB, and UVC.

National Institute for Occupational Safety and Health (NIOSH) Hazards to Outdoor Workers:  UV Radiation

Provides information about the risks of UV radiation to outdoor workers, symptoms of sunburn and first aid tips.  NIOSH also provides a listing of recommendations for protection from UV radiation that   employers can distribute to workers who perform duties outdoors.

Travelers Health –Yellow Book: Chapter 2, the Pre-Travel Consultation Sunburn

Provides information for travelers about overexposure to the sun, health risks from UV rays, and preventive actions that travelers can take to avoid overexposure.

Skin Cancer Prevention Progress Report

In July 2014, the Office of the Surgeon General released The Surgeon General’s Call to Action to Prevent Skin Cancer, establishing skin cancer prevention as a high priority for our nation. The “Skin Cancer Prevention Progress Report” summarizes recent prevention efforts and highlights new data, developments, and success stories following the Call to Action.

Artificial Tanning Sunbeds: Risk and Guidance [PDF – 4 MB]

While the World Health Organization (WHO) does not recommend the use of UV tanning devices for cosmetic purposes, it is recognized that sunbeds continue to be available to the public. This practical guide, prepared by Craig Sinclair, WHO, is intended for government health authorities, to assist them in the development of public health policy in relation to sunbeds.