What is the UV Index?

understanding the uv index

The Sun Authority

Did you know that the risk of UV damage to your eyes and skin correlates with your geographic location? For example, someone who is on vacation in Alaska is in less of a risk zone than someone who is sunbathing in Florida.

In the United States, the strength of UV radiation is measured by the UV Index. The National Weather Service calculates the UV Index daily so that people in all areas of the country know how at-risk they are. Season, variations in weather, cloud cover, elevation, and depletion of the ozone layer are all factors that determine the daily UV index, which is measured on a scale from 1 to 11+.

What the UV Index Scale Means:

0-2: Low Risk

This means you’re in a low-risk zone. Even though the risk is low, remember that it’s still important to wear sunglasses on sunny days, or when you’ll be around snow, water, or any reflective surface.

3-5: Moderate Risk

This means you’re in a moderate-risk zone. Ensure you wear sunglasses and avoid being in the sun during the afternoon hours when sunlight is strongest.

6-7: High Risk

This means you’re in a high-risk zone. You run the risk of harm if you venture into the sun unprotected. Wear sunglasses and a wide-brimmed hat, and use at least SPF 15 sunscreen. Try to stay inside during the afternoon hours.

8-10: Very High Risk

This means you’re in a very high-risk zone. You should take extra measures to stay protected. Stay in the shade whenever possible, and always be armed with sunglasses, a wide-brimmed hat, and at least SPF 15.

11+: Extreme Risk

This means you’re in an extreme-risk zone. You need to take all measures to stay protected, including sunglasses, a wide-brimmed hat, and re-application every couple hours of a sunscreen with at least SPF 15 protection. If you’re on the beach, UV rays are increased, as the sun’s rays reflect off bright sand and water. In a beach situation, polarized sunglasses are best. Stay in the shade whenever possible.

The important lesson to take away is that low risk or high, your eyes and skin must be protected from UV rays. Sunglasses with 99 to 100 percent UV protection and at least SPF 15 sunscreen will keep you healthy and having fun in the sun. Be sure to check out our pages on protecting your eyes and skin for more info!

UV Rays On Cloudy Days

Just because you can’t see the bright, shining sun doesn’t mean it can’t hurt you. UV rays can still zap you on cloudy days, and it’s just as important to wear sunscreen on these days as on sunny days. Basically, we recommend wearing sunscreen all day, every day, year-round. If that’s not feasible, at least check the UV Index so you’re prepared.

As for your eyes, sunglasses are a must — yes, even on cloudy days. Don’t go driving in the dark, though. There are certain lens tints that enhance vision and create contrast on an overcast or cloudy day. Try amber, brown, light blue, rose, or yellow-tinted sunglasses for low-light situations. You can learn more about the benefits of different lens tints here.

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