Chemical vs. Physical Sunscreen. Which is Best?

Photo: Bare Republic

There’s good reason to slap on sunscreen whenever you head outside – skin cancer is the most commonly diagnosed cancer in Canada. And Nova Scotians have some of the highest rates of skin cancer in the country.

But it can be confusing to pick a sunscreen that’s right for you. Visit a pharmacy in the summer and you’ll see shelves of sunscreen in every imaginable form – cream, foam, lotion, stick and spray.

Some labels say “mineral,” “chemical-free” or “natural,” which doesn’t give much insight on what the sunscreens contain or how they work.

There are two types of sunscreen: chemical and physical. Both stop harmful UVA and UVB rays from damaging the skin, but they do so in different ways.

Chemical sunscreen helps the skin absorb and release UV rays. It contains chemicals like oxybenzone, octinoxate, octisalate and avobenzone that absorb into your skin. When you’re out in the sun, those chemicals interact with the UV rays, creating a chemical reaction that transforms the UV rays into heat. Your skin then releases that heat.

It takes time for the sunscreen to absorb: that’s why the bottle will recommend applying the sunscreen 20 minutes before heading out in the sun, otherwise you will burn.

People with sensitive skin may find chemical sunscreen irritating or stinging, particularly higher SPF sunscreens, which contain more chemicals to provide broad-spectrum coverage (from both UVB and UVA rays).

A recent study published in the Journal of the American Medical Association reports that the chemicals do go into the bloodstream. However, there is no data yet on whether or not they harm the body.

Physical sunscreen blocks UV rays. It contains mineral ingredients like zinc oxide or titanium dioxide, which form a protective layer on top of the skin that deflects the heat and energy from the sun. The minerals don’t sink into your skin – that’s why mineral sunscreen is often recommended for people with sensitive skin (and why most sunscreen for children is mineral based).

As soon as you slather on a physical sunscreen, it’s effective. But you’ll need to reapply it after sweating, swimming or any activity that might rub it off.

Physical sunscreen can leave a chalky residue on the skin, but some formulas contain finely ground minerals that eliminate the problem. Or, you can always channel your inner California lifeguard and rock a fun neon colour. Some physical sunscreens are made just for that purpose.

The bottom line
Ultimately, picking the right sunscreen comes down to personal preference. Look for a product with a minimum SPF of 30 that has broad-spectrum coverage. That means it will protect you from the sun’s UVB rays (the rays that cause sunburn) and UVA rays (these rays penetrate deeper, aging skin cells, and causing wrinkles and skin cancer).

What matters most is using sunscreen diligently – every time you’ll be spending time in the sun.

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