Important FYI's on SPF
Grace Weatherby
/ Categories: WELLNESS, 2023

Important FYI's on SPF

Packing away heavy sweaters and wool socks in favor of shorts and tee-shirts is one of the most looked-forward to rites of spring. But as you do that, don’t forget one of the most important parts of a summer wardrobe isn’t kept in a closet or dresser.

I’m talking, of course, about sunscreen.

Wearing sunscreen every single day is one of the best things you can do to protect your skin. Not only does daily use reduce skin cancer risk, but it also helps prevent premature skin aging caused by ultraviolet (UV) rays from the sun including fine lines, wrinkles, and discoloration.

But with so many products on the market, it’s hard to know which to choose. Among your first considerations should be a product’s SPF level and broad-spectrum qualities. Here’s why they matter:


SPF stands for ‘sun protection factor.’ An SPF number tells you the amount of time that a product will protect you from getting a sunburn, specifically from the sun’s UVB rays. For example, if you begin to burn 20 minutes after being in the sun with no sunscreen, using an SPF 30 sunscreen will increase that time to 600 minutes (20 minutes x 30 SPF).

While sunscreen is available with SPF levels of 15, 30, 50, and 100, it’s always a good idea to reapply every two hours, especially if your active outdoors.

Broad Spectrum

Broad spectrum refers to products that protect you from both UVA and UVB rays, both of which can damage skin. UVA rays are associated with skin aging while UVB are associated with skin burning. That said, both UVA and UVA rays can lead to skin cancer. Only products labeled broad spectrum offer protection from both types of rays.

Of course, no sunscreen—no matter how expensive or high the SPF level—will work if you don’t use it properly.

As a rule, one ounce of sunscreen applied over the body is enough for most people (for a frame reference, one ounce is about a shot glass-worth’s). For the face, an additional nickel-sized dollop should be applied. To protect your lips, invest in an SPF lip balm and reapply whenever you reapply your sunscreen.

The Skin Cancer Foundation recommends applying sunscreen 30 minutes before going outside, then reapplying every two hours and immediately after swimming or sweating. Be aware that no sunscreen is waterproof, only water-resistant. If you’re spending time in the water, pay special attention to the clock and re-apply as soon as you get out.

A special note to anyone with small children…

If you have a child less than six months old, it’s best to keep them out of the sun rather than applying sunscreen to their delicate skin. When outside, make sure their clothing covers their tender arms and legs and use a hat to protect their face. Whenever possible, use umbrellas or other sunshades to minimize their exposure and avoid direct sunlight between the hours 10 a.m. and 2 p.m. 

One final thought before you head outside: remember that sunscreen does have an expiration date. Sunscreens are formulated to have a shelf life of up to three years when stored in a cool dry place. The three-year life applies whether they've been opened or not. Sunscreens stored in direct sun or high heat (think of that bottle so conveniently kept in your car) will degrade faster and not offer the level of protection you anticipate. In other words, taking good care of your sunscreen means it will take good care of you.


Lixia Ellis, MD, PhD is a dermatologist at SVMC Dermatology.

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