Get the Facts on Sunscreen!

June 26, 2021 By ,

We are looking at some seriously hot temperatures this weekend in the PNW, and this forecast seems to be just the beginning of what could be a very warm summer. That means that many of us will be heading into the great outdoors to enjoy the sunshine as well as seek refuge from the heat at home. But getting outside in the summer can increase your risk of sunburn. Sunscreen is always your best option to avoid a sunburn’s searing pain and potential risk of skin cancer later. But how do you choose the right one? Let’s take a look at what’s considered the right SPF, the right type, and how to apply it.

What is SPF?
SPF stands for Sun Protection Factor. The SPF numbers you see on bottles and tubes indicate the amount of time you can be in the sun while wearing that formula and avoid burning as compared to the time it would take to get the same level of burn without any sunscreen. That means that applying SPF 15 sunscreen will give you 15 times the amount of sun exposure than you would have without it before you start to toast in the sun. What the means is that SPF 30 will give you 30 times the amount of time in the sun before you start to burn. From there, you start getting into SPF 50, SPF 100, and sometimes even higher.But there are a few catches to that scale of time. Factors such as skin type, location on the globe, weather conditions, and even some medications can alter your base level of time before you start to burn without sunscreen. That means that your prolonged time in the sun with sunscreen also changes with these factors. Fair skin, proximity to the equator or the sun (higher sea level), less clouds, and some antibiotics can all make you more likely to burn more quickly.

SPF can also indicate the amount of ultraviolet (UV) light blockage. Sunscreens with SPF 15 will block approximately 93% of UV rays. SPF 30 will block 97% of rays. SPF 50 blocks 98%, and SPF 100 blocks 99%. That’s why you should always use at least SPF 30 when you’re choosing a sunscreen.

What is Broad-Spectrum Sunscreen?
There are three types of UV light that we get from the sun: UVA, UVB, and UVC. UVA rays cause skin aging as they penetrate below the surface of the skin and effect the firmness and elasticity of your collagen fibers there. UVA rays are what give you a tan by increasing melanin production in the skin. UVB rays are the nasty ones that cause sunburns and skin cancer. We don’t worry too much about UVC rays since they are repelled by (what’s left of) the earth’s ozone layer. When you’re shopping for a sunscreen, always look for the ones labeled “broad-spectrum.” These kinds of sunscreens block most of the types of UV light from the sun.

Mineral or Chemical?
Sunscreens can generally be divided into two groups: mineral and chemical. These two types of sunscreens work on different principles of UV light protection.

Mineral sunscreens sit on top of the skin and work like a reflecting shield to bounce the UV rays off the skin. They usually contain zinc oxide with or without titanium oxide and can also sometimes contain other chemicals that should be on the label. They are effective right after you apply them.

Chemical sunscreens absorb the UV rays and then release them as heat. These are made with chemicals such as avobenzone, octinoxate, oxybenzone, and homosalate that are carbon-based rather than minerals. These sunscreens take up to 30 minutes to be effective and must be applied before going into the sun. There is evidence that these chemicals can be absorbed into the blood stream also. When buying these sunscreens, look for those that are labeled “reef safe” as some of
these chemicals can damage coral reefs.

How Do I Put on Sunscreen Correctly?
First, you should apply your sunscreen at least 30 minutes before you go outside. This allows the sunscreen to have enough time to provide the maximum benefit. You may need to wait less time if you are using a mineral sunscreen but read the label to be sure.

Use enough to cover your entire face and body but don’t get it in your eyes or mouth. An average-sized adult or child needs at least one ounce of sunscreen to evenly cover the body from head to toe.

Reapply at least every two hours, and more often if you’re swimming or sweating. There is no such thing as waterproof sunscreen, so reapply after you drip dry or towel off. However, there are water-resistant sunscreens that will stand up better to water and sweat. These types of sunscreens usually indicate on the label the amount of time they will resist water.

And even if it’s cloudy, you should still apply sunscreen. UV rays can penetrate clouds up to 80%!

Be sure to cover these frequently forgotten spots:

  • Ears
  • Nose
  • Lips
  • Back of neck
  • Hands
  • Tops of feet
  • Along the hairline
  • Areas of the head exposed by balding or thinning hair

The Take Home Message
At the end of the day, the key to sunburn prevention involves picking a high enough SPF and reapplying the sunscreen regularly. I recommend a broad-spectrum sunscreen with no less than SPF 30. You should never go more than two hours before reapplying your sunscreen. And remember that there is no such thing as a waterproof sunscreen. If you are sweating or going for a dip, you should reapply more regularly.

I wish you all a great start to the summer! Please take care, stay cool, drink your water, and wear your sunscreen!

Seth Alley, DC, CCSP

Clinic Director

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