PHOENIX - Most of us have heard of the UV Index. It's a scale used in the United States to rate the harmfulness of ultraviolet sun rays on our skin.

In case you don't have a UV Index handy, use this easy rule to tell you how much harmful sun exposure you are getting.

It's called the "shadow rule."

* If your shadow is TALLER than you are, then your UV exposure is low.

* If your shadow is SHORTER than you are, you are getting higher levels of UV radiation. Protect your skin and eyes and seek shade from direct sunlight.

Next time you're outdoors try it. You'll find that your shadow is taller in the early morning and late afternoon, and shorter around midday.