The UV Index

for Measuring Ultraviolet Radiation Risk

The U.S. National Weather Service daily forecasts of ultraviolet levels use these numbers for various exposure levels:

UV Index Number	Exposure Level	Time to Burn	Actions to Take
0, 1, 2	Minimal	60 minutes	Apply SPF 15 sunscreen
3, 4	Low	45 minutes	Apply SPF 15 sunscreen; wear a hat
5, 6	Moderate	30 minutes	Apply SPF 15 sunscreen; wear a hat
7, 8, 9	High	15-25 minutes	Apply SPF 15 to 30 sunscreen; wear a hat and sunglasses
10 or higher	Very high	10 minutes	Apply SPF 30 sunscreen; wear a hat, sunglasses, and protective clothing

"Time to Burn" and "Actions to Take" apply to people with fair skin that sometimes tans but usually burns. People with lighter skin need to be more cautious. People with darker skin may be able to tolerate more exposure.