Sunscreen: How to Choose and Use It Properly

Look for three things on the label: broad-spectrum protection, which covers both UVA and UVB rays; an SPF of 30 or higher; and water resistance if you will be swimming or sweating. In Canada, sunscreens are regulated by Health Canada.

Mineral sunscreens use zinc oxide or titanium dioxide and are often better tolerated by sensitive skin. Chemical sunscreens absorb UV and tend to feel lighter and leave less white cast. Both work well, and many Korean and European sunscreens use newer filters that feel elegant on the skin.

Higher SPF numbers add a little more protection, but how much sunscreen you apply matters more than the number on the bottle. The best sunscreen is the one you like enough to wear every day.

Most people apply only a quarter to half of the amount used in SPF testing, so they get far less protection than the label says. A good rule is about two finger-lengths for the face and neck, and about a shot glass (30 mL) to cover the body.

Apply sunscreen as the last step of your morning routine, before makeup, and give it a few minutes to set. Do not forget your ears, the back of your neck, your hairline, the tops of your feet and the backs of your hands. A long-handled applicator helps with your back.

Reapply every two hours when you are outdoors, and right after swimming, sweating or towelling off. Shade, a wide-brimmed hat, UV-blocking sunglasses and clothing add protection that sunscreen alone cannot provide.

A tan is the skin's response to DNA damage from ultraviolet light. There is no such thing as a safe tan, and a base tan provides only minimal protection, roughly equal to a very low SPF.

Indoor tanning beds emit concentrated ultraviolet radiation and are linked to a higher risk of melanoma and other skin cancers, especially when people start using them young. Sunless tanning lotions and sprays are a much safer way to get a tanned look, though they do not protect against the sun.

Check the UV index each day. When it is 3 or higher, sunscreen, shade, a hat and sunglasses all matter, even on cool or cloudy days, because most UV passes through clouds.

Makeup and moisturizers with SPF rarely give the protection on the label, because people use far less than the amount used in testing. Wear a dedicated sunscreen underneath and treat SPF makeup as a bonus.

People with darker skin still need sunscreen. Melanin offers some natural protection, but it does not prevent sun damage, uneven pigmentation or skin cancer.

We live longer and spend our time very differently than our ancestors did, so their habits are not a useful guide. Sun protection today is about preventing skin cancer and early aging over a long lifetime.