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UV Exposure Categories

What is the Ultraviolet (UV) Index?

In response to the increasing incidence of skin cancer, cataracts, and other effects from exposure to the sun's harmful rays, the National Weather Service (NWS), the US Environmental Protection Agency (EPA), and the Centers for Disease Control and Prevention (CDC) collaborated on a sun-awareness information program. An important part of this program is the Ultraviolet (UV) Index, developed by the National Meteorological Center of the National Weather Service.

The Index is a next-day forecast that estimates the amount of ultraviolet radiation that will reach the earth's surface - providing important information to help you prevent overexposure to the sun's rays. The Index also includes the effects of cloud cover on the anticipated UV exposure level for the next day.

What are the UV exposure categories?

Index Values

Exposure Categories

0 - 2

Minimal - An index reading of 0 to 2 means minimal danger from the sun's UV rays for the average person.

3 - 4

Low - An index reading of 3 to 4 means you may be at risk of skin damage from the sun's rays - many people can experience a sunburn in 45 minutes.

5 - 6

Moderate - An index reading of 5 to 6 means you may be at some measurable risk of skin damage due to the sun - many people can experience a burn in only 30 minutes.

7 - 9

High - An index reading of 7 to 9 means you may be at high risk of harm from unprotected exposure to the sun - many people can burn in under 15 minutes.

10 +

Very High - An index reading of 10 and above means you are at maximum risk of harm from unprotected sun exposure - many people burn in as little as 10 minutes without protection.

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