Understanding SPF and UV radiation
Sunscreens are rated by their sun protection factor (SPF), which measures their ability to block out UVB radiation. Though sunscreens with an SPF of up to 100 are now available, Health Canada says they don't provide as much protection as you'd think. For example, SPF 15 sunscreen blocks 93 per cent of UVB rays, whereas, SPF 30 only provides an additional 4 per cent protection. So don't worry about splurging for the bottle with the higher SPF, but make sure it's at least 30, says the Canadian Dermatology Association.
Victoria Hudec, an outreach officer at Environment Canada, points out that there are two other types of UV radiation: UVA and UVC. UVC doesn't reach the Earth because the atmosphere filters it out, but UVA does hit us, and has a number of harmful effects.
Long-term exposure of UVA can also prematurely age and wrinkle skin, says Hudec. Long-term exposure to UVB can cause skin cancer and eye cataracts, and both UVA and UVB rays cause sunburn.
Environment Canada puts out a UV index that ranges from 0 to 11-plus, and "is included in your local weather forecast whenever it is forecasted to reach 3 or more that day," says Hudec. It is divided into categories with accompanying skin protection tips.
A UV index of 3 to 5 is considered moderate and Environment Canada advises you take precaution if you will be outside for 30 minutes or longer. Six to 7 is high and is damaging to the skin. Avoid the sun between 11 a.m. and 4 p.m., but if you are out, slather on sunscreen and wear sunglasses and a hat. A UV index of 8 to 10 is very high, and means skin will burn quickly. An index of 11 or higher is considered extremely dangerous but usually isn’t found in Canada.
Page 1 of 2 - what to look for when shopping for sunscreen on page 2.
