sunscreen explained: spf, pa ratings and more
why you should reapply often and even wear it if you're staying indoors.
5 minute read
everything you need to know about sunscreen.
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the first few heat waves of summer have hit in what will likely be a summer spent primarily outdoors, and the sunburns are already starting to roll in.
at this point, most sun-bathers are aware that burns are a primary cause of skin cancer, however, not many are aware that any unprotected exposure to the sun can play a role in developing cancer – even if you’ve perfected the art of getting that golden tan without burning.
tanning is a sign that the skin is taking damage, according to the fda. as a protection measure, the skin releases melanin to try and stop the uv rays from penetrating any further, but the damage has already been done.
over 80,000 people in canada are diagnosed with skin cancer each year, with more than 5,000 being melanoma, the deadliest form of skin cancer, according to the canadian skin cancer foundation. approximately 90 per cent of skin cancers are caused by exposure to the sun’s uv rays, so protecting yourself is important.
sunscreen is typically the first line of defence when it comes to being outdoors, although it’s not the only method of protection in the sun. we spoke to dr. rohan bissoondath, physician and a founder of preventous collaborative health, about how to stay safe this summer.
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know your spf and pa ratings
sunscreens typically comes with an spf, or sun protection factor. this rating gives an indication of how well the sunscreen will protect you from harmful uvb rays, a type of ultra-violet light given off by the sun that can cause damage to your skin cells like burns and blisters.
the spf number is an indication of how much more you will be protected than if you went without the sunscreen. for example, an spf rating of thirty means that, under ideal conditions, it will take approximately thirty times longer to get a sunburn, according to skincancer.org.
however, uvb radiation isn’t the whole story when it comes to potential sun damage. while uvb rays cause immediately visible damage to your skin, uva rays have a longer wavelength and can penetrate more deeply. this damages the dna in the innermost part of the top layer of your skin, the area where most skin cancers occur, according to bissoondath.
“exposure [to uva] causes genetic damage to cells on the innermost part of your top layer of skin, where most skin cancers occur,” says bissoondath. “the skin tries to prevent further damage by darkening, resulting in a tan and premature aging.”
“broad spectrum” sunscreens contain ingredients that help block both uva and uvb rays, reducing your chance of developing skin cancer and premature ageing.
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some sunscreens now include a rating system alongside the spf rating, to help consumers determine how much protection they are getting. the pa rating (which stands for protection of uva), ranges from one plus (pa+) to four (pa++++), with four pluses being the most protective against uva.
most medical-grade sunscreens will carry a pa++++ rating, as well as a higher spf. if you are unable to find a sunscreen that uses the pa system, bissoondath recommends looking for ingredients like zinc oxide and avobenzone – both of which protect against uva and uvb rays.
know your ingredients and formulations
in general, sunscreens can be divided into two broad categories: chemical and physical. chemical sunscreens use ingredients like avobenzone and octisalate to absorb the sun’s rays before they can cause damage while physical sunscreens include minerals like titanium dioxide and zinc oxide to scatter and block the sun’s rays before they gets to your skin.
consumers may find that one type of sunscreen is more comfortable or easier to put on than another, but all these ingredients have been tested and shown to be effective at protecting the skin. so if you’re trying a chemical style sunscreen and find that it irritates or dries out your skin, try a physical sunscreen – or one that combines both types of ingredients.
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bissoondath says that reactions to sunscreens are rare, however, when trying any new product on your skin it’s best to do a patch test first. apply a small amount to the inside of your arm and wait for 24-48 hours to see if you’ve reacted. sensitives may also develop with any kind of skin care product with extended use.
many other skincare products also include an spf factor, like moisturizers and bb creams, however they may not include uva protection. if want to primarily rely on these products, make sure they have a broad-spectrum protection, that you put enough on, and that every area of exposed skin is protected.
reapply often – even when you’re indoors
the most common mistake people make when using sunscreen is not using enough and not reapplying. most spf ratings are dependent on applying a thick layer of sunscreen over your entire body and re-applying every few hours throughout the day, as the ingredients will break down over time.
it’s also important to wear sunscreen indoors, in the winter, or if it’s cloudy out, as uva rays can penetrate through both windows and clouds. even in an office environment (remember that?), blue light from our computers and led lights give off high-energy visible light (hev), which can penetrate the outer-most layer of our skin cells.
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“both hev light and the sun’s uv rays generate free radicals, or reactive oxygen species, which cause skin cells to produce enzymes that break down collagen and elastin in the skin,” says bissoondath. “even though hev light is not associated with skin cancer, unlike uv rays, you can benefit from using sunscreen inside if you want to prevent early signs of ageing.”
look for quality sunscreens
recently there have been a range of controversies where independent labs testing products off the shelves don’t get to the spf ratings advertised on the bottle.
bissoondath recommends looking for sunscreens that are health canada approved and have the skincancer foundation seal. canadians can also report adverse reactions or complaints about the quality of sunscreens to health canada.
finally, to protect their skin, sunscreen isn’t the only method consumers should be practicing. other things to look out for include wearing protective clothing, hats, and planning outdoor activities for times when the sun isn’t at its peak.
to make sure you are getting the protection you need, talk to a skin specialist or doctor to get expert advice, and opt for medical-grade sunscreens and skincare products that are backed by science.
