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What’s the best SPF for sunscreens? Are we over-emphasizing SPF?

A common question I receive is what is the best SPF for my sunscreen/moisturizer? Let’s break down what SPF (Sun Protection Factor) means and dispel some commonly misunderstood concepts. I also pose the question “are we over-estimating the value of SPF?” 

1. What is SPF? And is a higher SPF better? 

The SPF is simply an equation that relates to how effective something is at blocking UV B radiation (not UV A radiation).

If it typically takes you 10 minutes to burn, SPF will prevent a burn for 15 x 10 minutes or 150 minutes. SPF 30 would be 30 x 10 or 300 minutes, etc. This is because UV B is typically responsible for sun burns as explained below. 

In regards to percent of UV B rays blocked, SPF 15 blocks 93% of UV B, SPF 30 blocks 97%, SPF 50 blocks 98%, etc. So you can see that the scale tends to flatten out, with the benefit of sunscreens over SPF 30 becoming negligible. Don’t forget that these numbers apply at a certain density of application, so if you are not applying enough sun screen, you are not getting the advertised amount of UV B protection. 

2. So are we over-emphasizing SPF? 

Naturally you would think, the higher SPF would be better, right? However the fact is that there is not only UV B radiation, there is also UV A radiation. UV A is deeper penetrating and is known to be the more likely contributor to development of skin cancers and skin aging. The UV B radiation has typically been more popularly addressed because it travels less deep and is responsible for the superficial “sunburns”. 

3. So how do I know how much UV A protection is in my sunscreen? 

Look for words like “UV A/UV B protection” or “Broad Spectrum” on your sunscreens to ensure both UV A and UV B are protected. As of now, there is not a standard UV A rating scale. 

In 2007, the FDA proposed a new 4 star rating system based on UV A protection – which ranges from 0 stars (no UV A protection) to 4 stars (highest UV A protection). See more information from the FDA website here

Also look for products that contain the following ingredients which provide UV A protection: Ecamsule, Avobenzone, Titanium or Zinc dioxide. 

4. Are there non-sunscreen options? 

Don’t forget to simply cover up when you go outside! UPF (Ultraviolet Protection Factor) ratings for clothing can similarly indicate the amount of sun and UV radiation blocked by clothing. Find lightweight clothing and hats that keep you out of the sun’s harmful rays. Don’t forget to apply sunscreen to those hands, ears, and feet. And avoiding the sun between 10 am and 4 pm is best. 

Take away points: 

1. Apply sunscreen 30 minutes before going out. Re-apply sunscreens at least every 2 hours if expecting to be outside. Sunscreens don’t last all day!

2. Generally anything over SPF 30 is not providing additional benefit and can be misleading, since the rating scale does not account for the harmful UV A radiation. 

3. Find broad spectrum, UV A/UV B sunscreen and apply liberally. Most people under-apply their sunscreens. Recommendations for a 5’4″ adult is a golf ball size (1 oz) amount. You could be under-applying and therefore getting less protection than expected!

4. Wear protective clothing and stay out of the sun between 10am and 4pm if possible. 

5. I recommend annual skin examinations for anyone with extensive sun exposure. 

Call or email me with any questions or comments. Have a great weekend!

 

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