How much protection is enough?

When choosing sunscreen products, consider the SPF (sun protection factor), a measure of the time it would take a person to burn in the sun without sunscreen vs. the time it would take them to burn with sunscreen.

• SPF up to 15: These low numbers are used by people “working on their tans,” though dermatologists warn this level of protection isn’t enough to defend skin from sun damage and skin cancer. Labels now include a warning that these products aren’t proven to protect against skin cancer or skin aging.
• SPF 15 to 30: Current wisdom considers SPF 15 the minimum protection needed, but most healthcare professionals prefer people of all skin types and colours to stick with SPF 30, which blocks out 98% of UVB light.
• SPF 50: While it may be tempting to grab the sunscreen with the highest rating, according to the USUSFDA, there’s no proof that products with an SPF above 50+ are as effective as they’re rated.
• Broad-spectrum formulas: Since both UVB and UVA rays contribute to skin cancer and skin aging, it’s best to use a product that limits exposure to both. “Broad-spectrum” claims are limited to products with SPF 15+ that protect against both types of ultraviolet rays.
• Bronzers: A sun-free tan: The best way to protect your skin is to stay out of the sun. That’s where bronzers come in: they give you that sun-kissed glow, without exposing you to harmful ultraviolet light.

Remember that sunscreen isn’t just for beach days. “In my experience, those showing signs of premature aging have not consistently used sunscreen,” says Peggy Humphries, a licensed esthetician in Santa Cruz, California, who specialises in premature aging, sun damage, and acne. “The single best way to prevent photo-aging is to consistently use a sunscreen with an SPF 30 or higher every single day, rain or shine.”

What type of sunscreen is best?

Sunscreens are primarily chemical or mineral. Both filter out harmful UV light; the main difference is that chemical sunscreens absorb it, while mineral sunscreens reflect it. Choose a chemical sunscreen if:

• You want easy spreadability. No patience to rub in a mineral sunscreen? Opt for a sunscreen with a gentle chemical filter such as avobenzone.
• You don’t want a white sheen. Mineral sunscreens aren’t absorbed into the skin, so they can leave you looking a bit pale.

Choose a mineral sunscreen if:

• You have sensitive skin. Do chemical sunscreens make your skin burn or sting? Choose a skin-friendly mineral sunscreen with zinc oxide or titanium dioxide.
• You want to avoid chemicals. Key chemical sunscreen ingredients include forms of benzophenones, PABA, cinnamates, salicylates, digalloyl trioleate, and menthyl anthranilate. Long-term effects of these chemicals have not been systematically documented in human studies, but certain healthcare professionals and watchdog groups have raised concerns about chemicals such as oxybenzone, which may interfere with normal hormone systems in the body.

Whichever product you choose, make sure it protects from UVA radiation (the kind that causes aging and skin cancer) in addition to UVB.

How often should I reapply?

One factor that can affect SPF is how well the sunscreen stays on, even after you’ve broken a sweat or gone swimming.

• Water-resistant – Every 40 or 80 minutes: Sunscreens labelled “water-resistant” will indicate how long they work, so limit your swim to that amount of time.
• Sweat-resistant – Every 30 minutes: “Sweat-resistant” applies to products that offer protection after 30 minutes of heavy perspiration.
• Regular sunscreen – Every 2 hours: Whatever you’re doing, it’s a good idea to reapply sunscreen every two hours, at a minimum.