The safest countries are found in Scandinavia, with Finland boasting the lowest average (2.17) and Sweden, Norway and Denmark not far behind.
Closer to the equator the sun's rays have a shorter distance to travel through the atmosphere and therefore less of the harmful UV radiation can be absorbed. With increasing altitude less atmosphere is available to absorb UV radiation.
The maximum UVI of 25 is for the grid cell at 13.5° S, 172° W, centred on Cuzco in Peru. The city is at 3360 m a.s.l., with surrounding terrain extending to over 6000 m a.s.l. As the capital of the Inca empire, Cuzco seems to be well sited for sun worship.
The strength of the sun's ultraviolet (UV) radiation is expressed as a Solar UV Index or Sun Index. The UV Index does not exceed 8 in the UK (8 is rare; 7 may occur on exceptional days, mostly in the two weeks around the summer solstice). Indices of 9 and 10 are common in the Mediterranean area.
There are lower mean UVI at the regions which are northerly bordering on the Alps, Carpathians, Pyrenees and the north coast of Spain due to a high cloud cover reducing UV radiation in the atmosphere.
The UV index is listed on local weather reports. 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.
You hear people say it often - "Aussie sun is different from Europe's." However, the sun itself always has the same strength, regardless of the continent.
Credit: NASA's Earth Observatory/Robert Simmon NASA scientists analyzing 30 years of satellite data have found that the amount of ultraviolet (UV) radiation reaching Earth's surface has increased markedly over the last three decades.
Temperature does not affect UV radiation levels. The UV Index can be just as high on a cool or even cold day as it is on a hot one, especially if the skies are clear.
Health experts advise everyone, regardless of skin color, to use sunscreen with an SPF of at least 30. Although dark-skinned people won't get sunburned as quickly, they will still burn and are still susceptible to sun-induced damage—such as sun spots and wrinkles—and cancer .
UVA rays are the weakest, but they cause skin cells to age faster. UVB rays are a little stronger, and can cause sunburns and skin cancer.
UVI 1-2 is low, which generally means it's safe to be outdoors unprotected. Other classifications are moderate (3-5), high (6-7), very high (8-10) and extreme (11+). To some extent, the moderate to very high labels tell us little except that UV intensity is increasing.
The UV Index Scale
UV Index 3-5 means low risk of harm from unprotected sun exposure. UV Index 6-7 means moderate risk of harm from unprotected sun exposure. UV Index 8-10 means high risk of harm from unprotected sun exposure. UV Index of 11+ means a very high risk of harm from unprotected sun exposure.
While clouds do reduce some of the sun's UV rays, they don't block all of them, as the Skin Cancer Foundation explains. UVA rays can penetrate clouds, and they can also reach below the water's surface.
UV rays also reach below the surface of water—three feet of water blocks only 20 percent of UV rays. Sunscreen should be used even on cloudy days when up to 80 percent of UV rays can still reach the earth's surface.
According to the World Health Organization, water only reflects about 10% of the suns UV rays. Although it doesn't reflect as much as sand, this is still a significant amount of additional UV radiation that your body will be exposed to when you are in or near water.
Ultraviolet (UV) levels (the amount of damaging rays from the sun) are lower in the winter because the earth tilts away from the sun.
And while UV radiation is higher in summer than in winter, it is still present every day of the year. There are three types of UV radiation, categorised by wavelength: UVA, UVB and UVC. UVA can cause sunburn, DNA (cell) damage in the skin and skin cancer.
0 to 2: Low
A UV Index reading of 0 to 2 means low danger from the sun's UV rays for the average person. Wear sunglasses on bright days. If you burn easily, cover up and use broad spectrum SPF 30+ sunscreen. Watch out for bright surfaces, like sand, water and snow, which reflect UV and increase exposure.
On December 29, 2003, a world-record ground-level UV index of 43.3 was detected at Bolivia's Licancabur volcano, though other scientists dispute readings higher than 26.
Ultraviolet radiation causes DNA changes in the skin that can lead to premature aging and skin cancer.
Early Morning and Evening Sun
However, the sun still emits UV rays outside of peak daylight hours, even as early as 6-8 a.m. and as late as 4-6 p.m. That means you still need to wear sunscreen in the early morning and evening hours to protect your skin from the damaging effects of the sun.
What Does a UV Index 11 Mean? An index of 11 or more signifies an extreme risk of harm due to unprotected sun exposure. Routine protective measures are mandatory; otherwise, skin sunburns can occur even with minutes of exposure.
1. Alicante, Spain: For a daily dose of vitamin C. Located on Spain's southeast coast, Alicante has the highest number of sunny hours in Europe. With an average of 349 hours of sunshine per month (an average month has 730 hours in total, including nighttimes), it's a dream destination for sun lovers.
Svalbard is the place in Norway where the midnight sun occurs for the longest period. Here, the sun doesn't set between 20 April and 22 August.