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UV Index

The UV index forecasts the intensity of ultraviolet (UV) light for any given day. The index helps people know what precautions to take to avoid sunburn or other skin damage from being in the sun too long.

The UV index is listed on the weather page of many daily newspapers. Sun protection measures, such as wearing sunscreen, should always be taken when the UV index is 5 or above. The UV index is measured on a scale of 0 to 11+.

  • 0 to 2: Low exposure to UV rays is expected for that day. It is important to remember to wear sunglasses on bright days and to cover up the skin if it burns easily. Snow and water can reflect the sun's rays and increase the UV strength. Skiers and swimmers should take special care: they should wear sunglasses or goggles, and apply sunscreen with an SPF of at least 15.
  • 3 to 5: Moderate exposure is expected for that day. Anyone who will be outside should cover his or her skin and eyes. Staying in the shade between 10 a.m. and 4 p.m. when the sun is the strongest is best.
  • 6 to 7: High exposure is expected for that day. Protective measures include covering up by wearing a wide-brimmed hat and sunglasses, staying in the shade between 10 a.m. and 4 p.m., and using a sunscreen with an SPF of at least 15.
  • 8 to 10: Very high exposure is expected for that day. Protective clothing, a wide-brimmed hat, and sunglasses should be worn. Other protective measures include staying in the shade between 10 a.m. and 4 p.m. and using a sunscreen with an SPF of at least 15. Doing routine outdoor activities such as gardening or playing sports should be based on how long the person will be exposed to the sun.
  • 11+: Extreme exposure is expected for that day. Unprotected skin can burn in minutes. Everyone should cover up and wear a hat and sunglasses. White sand and other bright surfaces reflect UV and will increase UV exposure. It is very important to stay in the shade between 10 a.m. and 4 p.m. and to use a sunscreen with an SPF of at least 15. The sunscreen should be reapplied every 2 hours.
By Healthwise Staff
Primary Medical Reviewer William H. Blahd, Jr., MD, FACEP - Emergency Medicine
Specialist Medical Reviewer H. Michael O'Connor, MD - Emergency Medicine
Last Revised September 1, 2011

WebMD Medical Reference from Healthwise

Last Updated: September 01, 2011
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.