Explaining the UV Index, how it determines burn time, plus sunscreen tips

SYRACUSE, N.Y. – The official start of summer is next week! This is the time of year where the UV index becomes dangerous. How is it calculated and what do the numbers mean in terms of how long it takes to get sunburnt?

The UV Index ranges on a scale of 1 to 11, rarely but sometimes higher than 11. A low UV Index is 1-2 with a burn time of 60 minutes. A medium UV Index is 3-5 with a burn time of 45 minutes, this is when it is recommended to find shade during the middle of the day, which is peak UV index hours. A high UV Index is 6-7 with a burn time of 30 minutes, this is when you should limit your time outdoors in the sun. A very high UV Index ranges from 8-10 with a burn time of 20 minutes, which is when you should try to avoid the sun as much as possible during peak hours between 10am to 2pm. An extreme UV Index is 11 or higher with a burn time of 10 minutes or less, this is especially dangerous for your skin.

How is the UV Index range calculated? There are multiple factors including the atmospheric conditions, your location, and time of day. The sun angle also plays a big role, when it is the highest in the sky during the middle of the day, this is when the UV Index peaks. The ozone layer can impact the UV Index because it filters the UV radiation, if it is thicker/thinner in spots this can decrease/increase the UV radiation reaching Earth’s surface. The clouds also act as a filter in this way, when it is cloudier this can lower the UV Index. If you are at a higher elevation, the UV Index increases. Plus, the time of day you are outside makes a difference. The UV index is highest midday to early afternoon.

Looking at the year as a whole, the sun angle is the highest in the sky during the summer solstice, along with longer hours of daylight. This leads to more ultraviolet radiation reaching Earth and a higher UV Index. Summer begins at 4:50 PM on Thursday June 20th when the Tropic of Cancer is tilted the furthest towards the sun, causing the longest day and shortest night in the Northern Hemisphere.

Here’s some sunscreen facts and tips to stay safe in the sun. Make sure you use at least SPF 30 or higher, this blocks 97% of the suns rays. Also, use broad spectrum sunscreen that covers UVA & UVB. Keep in mind, most sunscreens only last 1-2 hours then you need to reapply. It is best to use waterproof sunscreen, which stays on better, especially when swimming or sweating. Mineral sunscreen is better for your body and the environment than chemical sunscreen. Look for zinc oxide and titanium dioxide if you want mineral sunscreen. Avoid sunscreen with oxybenzone, this can cause eye/skin irritation and is a hormone disruptor, which is in chemical sunscreens. Remember, most sunscreens expire after 3 years so toss any old bottles.

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