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Sun Protection 101

Posted by Administrator on 5/14/2015

Sun Protection 101

By Michael S. Spicer, MD


Do you ever have questions about sunscreen or sunblock? What works best? What SPF to use? Will using a higher SPF work better? Or even, what is SPF? Well we have all the answers to those questions.  It’s time for Sun Protection 101.

We know it can probably be a little overwhelming standing in the sunscreen aisle looking at the wide range of sunblock, sunscreen, kid’s sunscreen, anti-aging sunscreen blah, blah, blah. I’m sure in your head your wondering what is best and which one should I try? Well let’s start with the basics first.


What Are UVA and UVB? Ultraviolet (UV) radiation is part of the electromagnetic (light) spectrum that reaches the earth from the sun. It has wavelengths shorter than visible light, making it invisible to the naked eye. Ultraviolet A, (UVA) is the longer wave UV ray that causes lasting skin damage, like brown age spots and leathery skin, as well melanoma skin cancer. Ultraviolet B, (UVB) is the shorter wave UV ray that causes sunburns, skin damage, and non-melanoma skin cancer like basal cell carcinoma and squamous cell carcinoma. The UVA spectrum is broken down into UVA I and UVA II. Both are dangerous, but many sunscreens do not protect against UVA I. You have to read your sunscreen label to be sure it contains “broad-spectrum” protection”.

Tip: Only Zinc Oxide and Avobenzone protect against UVA I, and they cannot be combined, so your sunscreen must contain one of the two.

What is sunscreen?  Sunscreen is a cream, lotion or spray that is applied to the skin to protect the skin against the harmful rays of the sun. There are different types of sunscreen. Some, like chemical sunscreens, are absorbed into the skin and chemically convert the damaging UV radiation energy into benign, or safe energy such as heat energy. Other sunscreens protects your skin by reflecting and scattering UVA and UVB radiation away from the skin cells protecting. These are physical sunscreens, like zinc oxide and titanium dioxide. Many sunscreens combine both chemical and physical ingredients to achieve the desired protection.

Choosing which sunscreen to use is a matter of personal preference, but it must say “broad-spectrum” or “UVA I, UVA II and UVB Protection” on the label as recommended by the FDA. As long as you choose an SPF of at least 30, the current recommendation from the American Academy of Dermatology, you are providing adequate protection for your skin.

What is SPF? SPF – or Sun Protection Factor – is a measure of a sunscreen's ability to prevent UVB from damaging the skin. There is a complicated formula, but basically here's how it works: If it takes 10 minutes for your unprotected skin to start turning red, using an SPF 30 sunscreen theoretically prevents reddening 30 times longer – 300 or about 5 hours. Most sunscreens with an SPF of 15 or higher do an excellent job of protecting against UVB. A lot of people think that wearing double the SPF gives you double the protection.  This is false.

Fact: SPF, or sun protection factor, does not increase proportionally with an increased SPF number.  For example: SPF 15 filters out 93% UVB rays. SPF 30 is 97% and SPF 50 is 98%.  No sunscreen can block all UV rays. 

FDA has recommended that companies label their sunscreen with a maximum SPF of 50+.  Dermatologists usually recommend wearing an SPF 30 sunscreen daily.  If you're going to be outdoors, exercising, swimming, or doing any physical activity, it is recommended use an SPF of 50 and re-apply every 2 hours.

So the next time you’re in that sunscreen aisle look for labels that say:

·       “Broad-spectrum”

·       Zinc Oxide or Avobenzone

·       SPF 30 to 50

This time you’ll be equipped with the knowledge to make a sound decision.

Sources: http://www.skincancer.org/prevention/sun-protection/sunscreen







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