The ultraviolet index or UV index is a measurement of the strength of the sun’s ultraviolet rays. It is 0 in the dark of night and 10-11 in the middle of a summer day with no cloud cover. This index was developed by Canadian scientists in 1992. It has now been adopted by the World Health Organization and most government entities as a mechanism to assess the sun’s strength and make recommendations on sun exposure.

uv index

At first the numbers may seem random, but it is in fact a linear scale. So, if you determine that you are a skin type II and burn in 30 minutes at a UV index of 6, then you will likely burn in 15 minutes at a UV index of 12.

The UV index is one of the three key factors for managing your sun exposure. You need to know your skin type, which determines your reaction to sun, the UV index, how strong the sun is, and then determine the proper duration to give you a minimal erythemal dose of UV exposure to produce vitamin D and other healthy properties – including nitric oxide – without burning.

One of the easiest ways to know the UV index wherever you are is to download the free dminder app on your phone!

Want to understand skin type?