Sun Safety: A Public Service Announcement

On a “spring” day when the high was still 45F in Boston, I came across a highly practical blog posting "What Doctors Wish Patients Knew," by the American Medical Association. This edition talked about sun safety.

It struck me as so practical that I wanted to share it widely and waited a couple of months to when it felt like some of us might actually run the risk of exposing any skin to sun.

Here goes: A few highlights of the tips shared by two dermatologists, Drs Evelyn Jones and Klint Peebles.

First, the science. Always good to understand the underlying science when you want to get the best outcomes for yourself and your family.

UV A = for Aging (passes through glass)

UV B = for Burning (blocked by glass)

The ultraviolet light from sunlight causes damage and increases our risk of skin cancers. We break down that UV light into two main components: Ultraviolet A (longer wavelength, less energy) and Ultraviolet B.

UV A, according to Dr. Peebles, is the "aging" ray. UV A causes wrinkling, fine lines, and age spots, and DOES pass through glass, which is why people who drive a lot notice more sun spots and freckles on the left side of their face or left arms. So as I'm sitting at my desk inside, with the sun shining brightly on my face, it still makes sense to put on sunscreen, even if I'm stuck indoors for most of the day, just to avoid worsening wrinkles.

UV B is mostly blocked by glass. B is the "burning" ray.

The Best Protection is our Clothing

And second, the protections we can take. Covering our skin with clothes, hats, shoes is the best and most effective. For the skin that remains exposed, we typically have two choices: chemical vs physical sunscreens.

In his classic book, The Design of Everyday Things, Don Norman talks about how important it is that we understand how things work, so that we can use them most appropriately. He may not have been thinking about suncreens at the time, but his words certainly apply.

Rub IN and Absorb the Chemical Sunscreens

Chemical sunscreens—or what I think of as the regular sunscreens—contain active ingredients like oxybenzone, octinoxate, octisalate, and others. These must get rubbed into the skin. The molecule, say oxybenzone, absorbs the sun's rays and converts them into heat before they can penetrate the skin further and cause any damage. That's a chemical reaction and uses up the molecule of oxybenzone in the process. That's why you have to reapply regular sunscreen every couple of hours.

Three key implications:

First, for full effect, you have to wait before going outdoors, as much as 30 minutes!.

Second, chemical (or regular) sunscreens can lead to more sensitivities (eg rashes).

Third, they have to be rubbed in—parents who do the drive-by spray — aiming for those arms and legs as the kids run by, sometimes half-wet, aren't getting the effect they hope for. The sunscreens need to be rubbed in—a superficial layer on skin won't work as effectively.

The dermatologists also remind us that ideally using SPF 30 or more is preferred.

Zinc/Titanium Sunscreens Work Immediately

Physical sunscreens—the ones that have zinc oxide or titanium dioxide and make you look like a white ghost unless you rub them in deeply—work completely differently. They sit on the surface of the skin and deflect the rays. Unlike chemical sunscreens, they are effective immediately. Skin reactions are less common. And most of the "baby-proof" sunscreens are just physical blockers, because they're less likely to irritate babies (note that sunscreen is recommended at six months and older)

Apply Daily and Frequently

Lastly the doctors make the great point that if you're worrying about bottles that are nearing their expiration dates (typically these bottles last 3 years), then you're probably not using them right. They recommend daily use—cloudy days still allow 80% of the UV rays to pass through. Indoors still exposes you to UVA. And if you're out and about, between water and sweat, you should be reapplying every couple of hours.

That's our public service announcement on sunscreens. Of course the safest way to protect yourself is to stay covered and avoid the peak sun hours of the day. And by the way, stay safe and hydrated!