Saturday, May 30, 2015

Demystifying SPF

For this post, I wanted to help to demystify the FDA's SPF rating system. There is so much confusion and misinformation regarding the numbers on the bottle and what they mean.

So what is SPF?  What does it do?

SPF means "sun protection factor" and refers to protection from UVB rays, or the rays most responsible for burning the skin. The SPF number refers to an extension of time a person can be exposed to UV radiation before initial reddening of the skin occurs. For example, if an individual would normally start to redden after 5 minutes of exposure, an SPF of 10 - with proper application - would give him/her 50 minutes.

There are some very important things to clarify. First, this number is extraordinarily individual and a bit arbitrary, as any "safe" time in the sun will be different from person to person. Second, the SPF rating does not give any indication of protection from UVA rays, the rays that age the skin.
There is also the danger of false security. The lack of a burning response often keeps people out longer, exposing themselves to more UV radiation, skin aging, and cancer risk.

A higher SPF number also indicates protection from a larger percentage of the sun's rays, but again this can be misleading. An SPF of 15 screens 93% of UVB rays, while SPF 30 comes in at 97%, and SPF 50 at 98%. In my opinion, anything over SPF 50 is not really worth the return. The active ingredients needed to achieve that really high SPF could cause irritation, especially to a sensitive skin. Ironically, those with sensitive skin often opt for a higher SPF number, thinking it will provide their delicate skin more protection. Also of note is the FDA's decision to no longer legally recognize labeling above SPF 50.

So what SHOULD you do?
  • Look for a sunscreen with a SPF between 30 and 50, that also lists the product as "Broad Spectrum" (the only indicator of UVA protection)
  • Wear hats and sun protective clothing (If you can see through it, UV can get through it)
  • Seek shade between the hours of 10 and 4
  • Reapply immediately after swimming or sweating, or as a general rule every 2 hours

I hope this clears things up a bit! There are still a whole slew of topics I didn't get to this month, so I may be peppering some additional sun protection posts throughout the summer months. Have a question I didn't get to? Please feel free to email or leave it in the comments for me!