Environment Canada developed the UV Index to inform Canadians about the strength of the sun's UV (ultraviolet) rays. UV rays can cause sunburns, eye cataracts, skin aging and skin cancer. The higher the UV Index number, the stronger the sun's rays, and the greater the need to take precautions. The table below outlines the sun protection actions recommended at different levels of the UV Index.
UV Index Sun Protection
UV Index
Description
Sun Protection Actions
0-2
Low
Minimal sun protection required for normal activity
Wear sunglasses on bright days. If outside for more than one hour, cover up and use sunscreen
Reflection off snow can nearly double UV strength. Wear sunglasses and apply sunscreen
3-5
Moderate
Take precautions - cover up, wear a hat, sunglasses and sunscreen especially if you will be outside for 30 minutes or more
Look for shade near midday when the sun is strongest
6-7
High
Protection required - UV damages the skin and can cause sunburn
Reduce time in the sun between 11 a.m. and 4 p.m. and take full precautions - seek shade, cover up, wear a hat, sunglasses and sunscreen
8-10
Very High
Extra precautions required - unprotected skin will be damaged and can burn quickly
Avoid the sun between 11 a.m. and 4 p.m. and take full precautions - seek shade, cover up, wear a hat, sunglasses and sunscreen
11+
Extreme
Values of 11 or more are very rare in Canada. However, the UV Index can reach 14 or more in the tropics and southern U.S.
Take full precautions. Unprotected skin will be damaged and can burn in minutes. Avoid the sun between 11 a.m. and 4 p.m., cover up, wear a hat, sunglasses and sunscreen
White sand and other bright surfaces reflect UV and increase UV exposure