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.
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How do you protect again UVA?
SPF indicates the sunscreen's UVB protection, but there's no rating system for UVA protection. Heath Canada recommends broad-spectrum sunscreens, which offer protection against both types of radiation. These are sunscreens with physical filters, such as zinc oxide or titanium dioxide, which work by physically blocking, scattering and reflecting both UVA and UVB rays.
Not all suncreens that protect against UVA are labeled broad spectrum. "If it doesn't say broad spectrum on the bottle, check the label for Parsol 1789 or avobenzone," says Dr. Jason Rivers, a clinical professor of dermatology at the University of British Columbia and practicing dermatologist in downtown Vancouver. "This offers protection against UVA rays."
Environmental groups, such as Friends of the Earth and Environmental Working Group warn against the possible toxic effects of substances in sunscreens. Ingredients like zinc oxide, titanium dioxide and oxybenzone are all on their watch list. Dr. Rivers says these risks are more theoretical than real. Some studies have reported some adverse side effects in mice, but he says they have not been found in people.
Ashley Lemire, a media relations manager with Health Canada, says all sunscreens are regulated as drugs in Canada and have to meet certain criteria to be sold. Zinc oxide, titanium dioxide and oxybenzone are all on Health Canada's list of acceptable sunscreen ingredients, which "are recognized as safe and effective at the concentrations listed and are consistent with international scientific understanding," says Lemire. (Check out Health Canada's sunscreen guidelines here.)
Types of sunscreen
With the variety of gels, creams and sprays available, it can be confusing knowing which works best. Dr. Rivers says they're all essentially the same. "It's not the type of sunscreen, but how it's applied," he says. "Most people don't put enough on." About 2 tablespoons (30 millilitres),of sunscreen is what is needed to properly coat the entire body.
Look for the following to make sure you're getting proper skin protection:
• A CDA logo, which means the sunscreen has been evaluated and has met the guidelines of the Canadian Dermatology Association.
• A Drug Identification Number (DIN) or Natural Health Product Number (NPN) ensures the sunscreen is approved by Health Canada.
• An SPF of at least 30 for UVB protection.
• The words broad spectrum.
• Zinc oxide – Dr. Rivers says this is a safe substance that offers both UVA and UVB protection.
• A UVA blocker, such as avobenzone.
Other tips to protect yourself from sun damage
• Avoid prolonged sun exposure between 11a.m. and 4p.m.
• Wear wide-brim hats, and clothes that cover you up.
• Don't forget about your eyes! Always wear sunglasses.
• Reapply sunscreen after swimming or heavy perspiration.
• Don't confuse temperature and UV! UV rays can be damaging to the skin, even if it's cloudy or cold out.
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