What Is the U.V. Index

Every day on the weather report we hear about the U.V. Index. In the newspapers we read about the U.V. Index. So what is the U.V. Index? It’s simply a calculation that was derived by the National Weather Service and the Environmental Protection Agency to tell us how much damaging ultra-violet light to expect on any given day, in any given zip code. The U.V. Index ranges from a low of 1 to a high of 11 or even, over 11. And if you want to know what actual numbers are for each category, you can go to EPA.gov/sunwise, but the U.V. Index is calculated on the basis of the amount of cloud cover, the amount of ozone in the atmosphere and the actual altitude of where that zip code is. Certainly when there are no clouds, all the ultra-violet light is coming through but believe it or not, with a completely overcast day, 31% of the damaging ultra-violet still gets through the clouds. When there’s more ozone in the atmosphere, that ozone absorbs and neutralizes the dangerous ultraviolet light, when there’s less ozone more U.V. comes through. And for those mountain climbers and skiers out there, for every 3,000 feet above sea level you are, ultra violet increases 6%. When you see what the U.V. index is, don’t be lulled into a false sense of security if it’s a low U.V. index like one or two, because even on their website they tell you with a U.V. Index of either 1 or 2, you still need to use sunscreen everyday with an SPF of at least 15 because so much of sun damage, whether it’s premature aging or skin cancer, occurs because of the accumulation of small amounts of sun exposure whether it’s 3 minutes or 5 minutes, as well as spending a whole day at the beach, because of this accumulation, it’s really very important regardless of the U.V. Index, to make sure you’re wearing a sunscreen everyday with an SPF of between 15 and 30 with UVA protection. But, the U.V. Index, I think, is a very helpful measure to remind us every day, to wear that sunscreen.