Ask Karen Sunscreen

By Karen McNew
WSLS10 Anchor
Published: May 28, 2008

Click here to read past Ask Karen articles

Q:  Dear Karen, I have heard that after a certain SPF level in suntan lotion anything higher is useless.  Could you please answer what the
benefits of a higher SPF are?

A:  I didn’t realize sunscreen was such a complex topic until I started looking into your question.  SPF stands for Sun Protection Factor.

For instance, if you use SPF 15 Dr. Mark Greenawald says that means, “If a person burns within 20 minutes of sun exposure, and SPF of 15 will
theoretically allow them to be in the sun 15 times longer before burning.“

But, depending on many different factors SPF 15 or 30 or whatever you choose may not be giving you the protection you are counting on.
Many of you have heard anything higher than an SPF of 30 is useless.  While a higher number doesn’t necessarily mean better, it does mean sun protection for a longer period of time.  Doctor Greenawald says, if you are likely to burn and your looking for maximum sun protection you don’t want to use SPF 30 as an automatic cut off.

There are other factors that play into the amount of protection you are actually getting.

Dr. Greenawald says, “There are many things that will decrease the protection factor of sunscreen, and include; the skin type of the user,
the amount applied and frequency of re-application, activities in which one engages (for example, swimming or sweating lead to a loss of
sunscreen from the skin), amount of sunscreen the skin has absorbed as well as environmental factors such as wind, heat, humidity and
altitude.“ 

Experts estimate that in some cases with the above factors being taken into consideration, you may only be getting half the protection listed
on the label.  That’s not the only reason you may have a false sense of protection.

Dr. Greenwald says, the SPF is a level of protection against burning UVB rays but does not account for UVA rays.  UVA rays can also cause
wrinkles and skin cancer.

So, use a high SPF sunscreen for sure, but there are other ways to protect against harmful rays.

Dr. Greenawald says, “For greater protection against sun damage to the skin, it is recommended that people avoid the sun when it is most
intense (between 11 AM and 3 PM), wear a sunhat and protective clothing, and consider using a physical barrier sunscreen, such as zinc oxide or
titanium dioxide.“