The meaning and how to read it


  • The UV Index scale measures the intensity of the sun’s UV rays on a scale from 0 to 11+.
  • The lower the UV Index scale, the less likely your skin will tan in the sun.
  • The higher the UV Index scale, the greater the likelihood of burns and skin damage.
  • Visit the Insider Health Reference for more tips.

The sun’s ultraviolet (UV) rays can permanently damage your skin. In fact, ultraviolet rays are the main cause of skin cancers such as melanoma and basal cell carcinoma, speaks Beth Goldstein, Dermatologist with Central Dermatological Center

Therefore, it is important to keep an eye on the UV index in your area before spending time outdoors. It can help protect you from sun damage and subsequent health effects.

What is UV Index?

IN ultraviolet index or UV Index predicts the intensity of the sun’s UV rays on a scale from 0 to 11+.

Understanding the index will help you predict how quickly your skin will tan when exposed to sunlight and what preventive measures you should take if you plan to be outdoors. For example, the higher the UV index number, the stronger the UV raysand the faster you burn out.

The US National Weather Service (NWS) and EPA measure UV levels daily using computer model that analyzes surface UV strength along with predicted cloud cover and ozone concentration. You can see the UV Index forecast for your location on EPA website

To predict the intensity of UV radiation, the UV index takes into account:

  • Times of Day. Ultraviolet radiation is most intense between 10:00 and 15:00, when the sun is at its highest peak in the sky.
  • Season. Ultraviolet radiation is most intense in spring and summer because this is the time when the northern hemisphere is tilted towards the sun. Ultraviolet radiation decreases in the fall and is lowest in the winter as the northern hemisphere deviates from the sun.
  • Cloud cover. Heavy clouds can block UV radiation and lower the UV index.
  • Latitude… Latitude determines how close you are to the equator. The closer to the equator, the more intense the UV radiation.
  • Height… The higher the altitude, the stronger the UV rays. In fact, UV increases by about 2% for every 1000 feet of altitude.
  • Environmental factors… Trees or tall structures that block UV rays can reduce UV radiation levels. On the other hand, reflective surfaces such as water and snow can intensify UV radiation.

UV Index 0 to 2

An UV Index of 0 to 2 means you can expect low UV levels with minimal risk of sunburn. Debra Jaliman, MD, dermatologist with his own private practice and associate professor of the Department of Dermatology at Icahn School of Medicine at Mount Sinai

While an ordinary person can lie in the sun in an hour without burns“People with very fair skin should take precautions as they can burn themselves within 30 minutes,” says Jaliman.

UV Index 3 to 5

This is a moderate level of UV radiation, which means a moderate risk of burns if you are outdoors without sun protection.


According to Jaliman, the time it takes for your skin to burn at this level depends on your skin type, but generally speaking, a UV index of 3 to 5 can result in sunburn on average 30 to 45 minutes

To protect your skin, EPA recommends:

  • Looking for a shade from late morning to noon.
  • Use a sunscreen with an SPF of at least 30 on exposed skin.
  • Wearing a wide-brimmed hat, sunglasses, and protective clothing that helps block UV rays. It can be fabric with UV protection factor (UPF) 30 or morewhich means it is tightly woven and helps block UV rays.

UV Index 6 to 7

This is a high level of UV radiation, which means the average person can burn out in about 15-25 minutes without sun protection.

At this EPA level recommends:

  • Apply sunscreen with an SPF of at least 30 every two hours.
  • Wearing a wide-brimmed hat, sunglasses, and sun-protection clothing such as UPF fabric or long-sleeved trousers.
  • Avoid sun exposure during the hottest part of the day – from 10 am to 3 pm. If you need to be outside at this time, try to stay in the shade.

UV Index 8 to 10

This is a very high level of UV radiation with a high risk of sunburn. On average, you can expect a burn in about 10 minutes or less at this level of UV light, Jaliman said. EPA recommends you are taking extra precautions while outdoors, including all of the above.

“Do not go [outside] without serious protection, or just not going out, ”says Goldstein.

UV Index 11+

This is an extreme level of UV radiation, and exposure to the sun without protection at this level is dangerous. All safety precautions should be followed, including the use of sunscreen, sunglasses, wide-brimmed hats, and protective clothing. At this level unprotected skin can catch fire in minutes

Insider’s conclusion

The UV Index shows how strong the UV rays are at a specific location. This information will help you plan when to spend time outdoors and what kind of sun protection to use.

According to Jaliman, your risk of burns is higher the higher your UV Index reading, but no matter what the index says, you should always wear sunscreen when you spend time in the sun.

This may include using sunscreen with an SPF of at least 30, or wearing protective clothing such as a hat, sunglasses, or UPF clothing.

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