The Definitive Guide to Choosing a Sunscreen

Choosing an effective sunscreen is a bit more complicated than just picking your SPF. Here's what you need to know for full sun coverage

Credit: Flickr / Ashley Loves Pizza

Before baring your body, make sure your sunscreen will protect from both UVB and UVA rays

Sunscreen isn’t just for summer—it’s your year-round, anti-aging, anti-cancer armor, if you choose the right one

UV rays are present all year long, which is why I’m a firm believer that everybody should wear sunscreen every day, especially during the summer. Whether you do it for your health (to help prevent skin cancer), or for comfort (to help prevent burning) or for your vanity (to help prevent wrinkles and hyperpigmentation) the reasons for adding sunscreen to your morning routine are stacking up.

Sunscreens come in many forms now (cream, stick, spray, lotion and even powder) and the new generation of sunscreen formulas are much more effective and more comfortable to wear, so there’s definitely one that’ll fit your skin type and activity level. You may have to try a few before you find the right one, but it’s an investment in time and money that’ll pay off hugely in your future.

Photodamage: What UVA and UVB Rays Are Doing to Your Skin

Without any sunscreen, your poor, plump, delicate skin is being fried by UV rays, top to bottom, inside out. When you go outside and feel the warmth of the summer sun, that’s UV damage by UVB rays (think “b” for “burn”).

When you go outside on a cloudy day any time of the year, your skin’s still being damaged by the more insidious UVA rays (think “a” for “aging”). Those are the two main forms of photodamage that can be prevented by wearing sun protection. A broad-spectrum sunscreen used daily is your best protection to deflect and absorb harmful UV rays.

UVA represents about 95% of UV radiation reaching Earth’s surface, 20 times more than UVB rays. UVA rays are the invisible enemy (you don’t feel them like the warmth that comes from UVB) and are present all year round from sunrise to sunset. UVA can go through glass, windshields and windows, so lotion-up even if you’re “just” in your car. They will do long-term harmful damage to your skin (aging, cancer, allergies) as they penetrate all the way deep down to the dermis. Their effects could take years to surface but when they do, it’ll be ugly, as demonstrated in this New England Journal of Medicine image of a 69-year-old trucker.

UVB rays make up only about 5% of the UV radiation that reaches Earth’s surface, yet because its effects are discernible in the form of heat and darkening skin, most people still mistakenly perceive UVB as the only real threat. These rays are present predominantly during the summer and are strongest between 10 am and 2 pm.

When I see somebody who’s deeply tanned, all I see is the damage they’ve done to their skin. I think about how much UVB exposure it took to get to that level of tan (or burn) and think about how they’ve actually received 20 times that amount in the form of UVA rays.

I don’t buy into most of the “anti-aging” claims purported by the cosmetics industry, but I do believe sunscreens are the only true and best anti-aging practice we can adopt to prevent photodamage and signs of premature aging. And it’s not just wrinkles, but also hyperpigmentation, the thickening of the skin and the roughening up of its texture. UV rays really do a number on our delicate skin and it can all be largely prevented with an effective sunscreen worn daily. It’s easy, it’s inexpensive and the benefits are multiple.

What to Consider When Choosing a Sunscreen

You can’t judge a sunscreen by its container. Just because it says “broad spectrum” doesn’t mean it’ll protect you from UVA rays at all, and just because it says “UVA/UVB” doesn’t mean it’ll cover most or even part of the UVA spectrum, and just because it says “SPF60” doesn’t mean it’ll offer anything more than moisture and possibly a chalky white cast.

Yes, it’s possible to buy a name-brand sunscreen and have it offer you little sun protection. And even you find a good one, it’s useless if you don’t apply it correctly. So keep these pointers in mind:

SPF & UVB: SPF refers only to UVB rays, not UVA. So if the SPF is all you’re looking at when you buy a bottle or box of sunscreen, you may still be exposing yourself to the more harmful UVA rays.

PPD & UVA: Protection against UVA rays is measured in PPD (persistent pigment darkening). We don’t have any kind of measurement or standards for this in Canada or the US. Many other countries in Asia, Europe and in England already have a ratings system for UVA (albeit relatively new) but this concept is still not popular here, so people are largely unaware of this issue.

Unfortunately, to get a full understanding on how much UVA protection your sunscreen offers, you’ll need to read the active ingredients and learn which ones work and which ones don’t. Online calculators exist, such as the sunscreen simulator from BASF, but they only approximate and don’t take all factors into consideration. Still, they’re good for those starting to wrap their heads around this topic.

Photostability: This refers to a sunscreen’s ability to stay effective upon exposure to heat and light. Sun protection ratings are developed in vitro, that is, in controlled lab conditions. In the real world, some sunscreens actually lose much of their efficacy the second they’re exposed to the very elements they’re supposed to protect us from.

Photostability is dependent on a number of factors including the combination of ingredients used and the percentages of each active ingredient. Unless you have a background in organic chemistry, your best bet is to look for patented formulas that contain a combination of chemical ingredients with names like Mexoryl®, Tinosorb® and Helioplex®. These are generally regarded as offering broad spectrum protection and are photostable. All physical actives such as zinc oxide and titanium dioxide are photostable but don’t protect you from UVA rays.

Physical vs. Chemical: Sunscreens are generally of three kinds. If they contain physical blockers such as zinc oxide and titanium dioxide, they’re physical sunscreens and will deflect UV rays. Sometimes they’re labelled “all natural” or “chemical free” and are a good choice for those with particularly sensitive skin, although they can often leave a chalky white cast that is rather pronounced in flash photography. They’re great for protecting against UVB rays but offer little protection against UVA rays.

Sunscreens with ingredients such octocrylene, octinoxate and avobenzone are chemical sunscreens, which will absorb UV rays and dissipate them in the form of heat. Some people find avobenzone in particular to be irritating (and some avo-based formulations can stain light clothing), but chemicals are especially good at protecting you against UVA rays.

Then there’s the third kind: those that combine both physical and chemical ingredients, to give you the best of the both worlds. This type is very common.

Mixing Ingredients: Anytime you’re looking at a sunscreen with chemical ingredients, you need to be aware of how they interact with other ingredients, including any SPF actives in your makeup. Shockingly, products from name-brand labels can often contain chemicals that destabilize one another, greatly lowering your sun protection.

Avobenzone is one of the most common chemical actives in sunscreens, but needs to be stabilized, ideally, with octocrylene. Other chemicals such as oxybenzone will stabilize avobenzone too, but only partially. Stay away from products that mix octinoxate with avobenzone as this combination degrades very quickly.

When looking at sunscreens with both chemical and physical properties, avoid the avobenzone all together, as zinc oxide and titanium dioxide will both destabilize avobenzone (although the physical actives will remain intact).

If you’re layering makeup on top of your sunscreen, you need to check the ingredients of both products against one another and ensure, ideally, you’re applying like-for-like. If you’re mixing your chemicals, be aware that you could be destabilizing your sun protection. I think SPF in makeup is a great concept in theory, but ridiculous in reality and always try to buy makeup without any SPF just to avoid this issue all together.

¼ tsp: This is how much you need to use just for your face. Double it if you’re covering your neck and chest as well. It doesn’t sound like a lot but measure it out and you’ll be surprised at how much it actually is.

Sunscreens were designed to provide the advertised protection level only if applied at a coverage rate of 2 mg per cm2. Anything less and you reduce the protection exponentially. Apply ½ that amount and it’s not ½ the protection, it’s closer to 1/15. This is another reason why you shouldn’t rely on your makeup for sun protection. Outside of Kabuki theatre, absolutely no one should ever apply ¼ tsp of makeup to their face. 

Read more about recommended broad spectrum photostable sunscreens.