Without it, life wouldn’t exist, but too much of it can be harmful to your health. The Sun is a vital part of our everyday lives — up to a certain point.

Ultraviolet rays are invisible radiation emitted from the Sun. There are UV-A, UV-B, and UV-C rays. But we simply refer to them all by the blanket term “UV Rays”.

Most of the UV-A rays make it through our atmosphere. Most, but not all, of the UV-B rays are absorbed by the ozone layer. Some make it through. UV-C rays are completely absorbed by our ozone layer and that’s good because they’re the most harmful.

It’s the UV-A and UV-B rays that are the most harmful to our bodies. They cause premature aging and skin cancer. Most skin cancers are caused by over-exposure to these rays. They can also cause potentially blinding eye diseases and impact your body’s ability to fight off illness.

UV rays are measured with a number called the UV Index. The higher the index, the stronger the rays. In the summer, the index is much higher than in the winter. When we have high index values, you can burn in less than twenty minutes. The lower the UV ray index, the longer it will take to burn.

And speaking of protecting the skin, SPF 100 may be a waste of your time. Anything around SPF 30 is almost just as protective, blocking out 97% of the harmful rays. Nothing will block out 100%. According to a Health Day poll, 80% of adults know they should be applying sunscreen every two hours but only around 30% typically do.

The percentage of rays blocked versus the SPF value

But just when you think it’s not safe to be outdoors at all, UV rays actually do have benefits. The Centers for Disease Control recommend around 5 to 15 minutes of sun exposure 2 to 3 times a week. That’s because UV rays in very small amounts can help the production of vitamin D.