Everything You Need to Know About Sunscreen

No doubt you understand the need for sunscreen. But just having it on hand, occupying a shelf in your medicine cabinet, a desk drawer at the office, or a pocket in your beach/pool tote, isn’t going to do much to protect you from skin cancer and premature aging.

For that to happen, you need to know when to apply it and how much to apply. You also need to make sure you’re using the right kind. I know. It seemed like such a simple thing just a moment ago. Hang in there. It’s not as complicated as it seems.

Learn to speak the language

SPF. UVA. UVB. Sunscreen bottles are loaded with abbreviations. By now, we’re all familiar with them because we see them everywhere, especially during the summertime. But recognizing them and knowing what they mean are two very different things.

Let’s start with distinguishing between the two types of ultraviolet rays. UVA rays are the ones that sink deep into our skin and make it look older and feel rougher. UVB rays are the ones that cause sunburn and skin cancer.

SPF refers to the strength of a product’s shield against UVB rays. Broad spectrum SPFs protect you against UVB and UVA rays. The number refers to the amount of time you can spend in the sun while wearing that sunscreen, while simultaneously absorbing a minute’s worth of UVB rays.

In other words, wearing a broad spectrum SPF 15 sunscreen under the sun for an hour is like being exposed to four minutes of UVB rays without SPF, according to the American Cancer Society. An hour wearing SPF 30, then, would be like exposing yourself to just two minutes of UVB rays unprotected. No single sunscreen, however, will shield you from 100 percent of the sun’s rays. The American Academy of Dermatology recommends using a broad spectrum sunscreen with an SPF of at least 30.

Some sunscreens are also described as “water-resistant.” That means they’ll stay effective for at least 40 minutes in the water. The FDA banned the use of “waterproof” as a descriptor because there’s actually no such thing. “Sports” usually means that the sunscreen is water-resistant, though it’s not a term that recognized (or tested) by the FDA.

Know when to reapply

Generally, you want to apply sunscreen 15 minutes before heading outside, to give it a chance to soak into the skin. Then reapply it every two hours in order to maintain maximum coverage.

Sweating and venturing into water changes that equation a bit. If you expect to do either, use a water-resistant sunscreen, and reapply it every half-hour, to be on the safe side. For everyday use, a standard broad-spectrum SPF sunscreen will provide sufficient protection.

Apply the right amount

It’s always a good idea to apply sunscreen generously, but, at minimum, you should be using an ounce to cover your face, legs, arms, and neck, as well as another half-ounce for your torso, according to the American Cancer Society. If it’s easier, think in terms of using a quarter-size amount for each arm and leg and your chest, back, and head and neck. Include your scalp, too, if you have thinning hair or a closely-cropped haircut.

And, I know you’ve heard this before, but it’s worth repeating: Stick to these guidelines on cloudy days, too.