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Jul. 05, 2011

The Truth Behind SPF 100

by Ally Ruchman

Click to enlarge images

By Ally Ruchman, Rumson-Fair Haven Regional High School

Our whole lives we've heard that the higher the number on the sunscreen bottle, the better. But what does the number really mean? And is it necessary to use SPF 75 when 30 works just fine?

When going outside, doctors recommend using a broad spectrum sunscreen, which blocks out both UVA and UVB light. The lowest recommended SPF number by doctors is 15, which blocks out 93% of UV rays. Most sunscreens only block UVB rays, even though UVA are more harmful. Products containing UVA blockers list ingredients like zinc oxide or titanium dioxide. The best sunscreens have UVA and UVB blockers to prevent the damaging rays that potentially cause cancer from reaching and harming skin cells.

How big is the difference between SPF 15 and SPF 30? And what about SPF 30 and SPF 50? The truth is, once you go past 30, there really isn't much difference. SPF 30 blocks about 97% of UV rays, versus 93% in SPF 15. And SPF 50? Only 98% of UV rays. Higher numbers are just ploys made by manufacturers to get consumers to buy their products. The higher the number, the more likely a consumer will purchase their product because of the false belief that it will offer more protection. The truth is, when purchasing a sunscreen, don't rely on the number alone. The difference between 30 and anything above it is negligible. Instead, focus on the ingredients, and whether or not it blocks UVA rays. Also, ignore anything on the bottle about waterproof or long-lasting. They are more marketing techniques that are being shut down by the FDA.

So some handy tips for this summer? Make sure you read the entire bottle of sunscreen before purchasing, to make sure it offers proper protection. Don't fall prey to marketing tricks that will only end up costing you more money. Reapply, reapply, reapply. No sunscreen can last all day, especially if you've been in water. Stay out of the sun during the hottest part of the day, usually 10-4. And remember, have fun!

_______________________
Ally Ruchman is a junior at Rumson-Fair Haven Regional High School in Rumson, NJ. She loves animals, reading, science, and traveling.

About Ally Ruchman

The views expressed are those of the author and are not necessarily those of Science Friday.

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