Sunscreen & the Summer Sun

By David Harvey, MD

Happy Summer Solstice!  We are all yearning for sunshine in the Pacific Northwest after a rather grey and wet winter.  I want to encourage everyone to remember to wear sunscreen this summer.  Here are a few things about sunscreen we want to point out that are often misunderstood:


1. SPF (sun protection factor): an SPF of 30 means that you could be out in the sun 30 times longer before you get sunburned than you would be able to if you went out without sunscreen.


2. SPF is not linear in how much protection it provides, so an SPF of 15 is not ½ as strong as an SPF of 30. An SPF of 15 will block 93% of UVB rays and an SPF of 30 blocks 97% of UVB rays.  Most dermatologists recommend at least an SPF 30.


3. The sun gives off both UVA and UVB rays. We used to only look at the effects of UVB rays, so SPF is only related to UVB protection, not UVA protection. While UVB is a major cause of sunburn and skin cancer, UVA is also related to an increased risk of skin cancer and aging of the skin.  In addition, UVA rays can penetrate thru glass and are not blocked by the ozone, so when choosing sunscreen make sure it says, “UVA and UVB protection” or broad spectrum


4. Apply enough sunscreen to fill a shot glass for exposed areas (face/arms/legs) and reapply every 2 hours. It may seem like a lot, but most people do not apply enough sunscreen to ensure full coverage. If you’re also covering your torso, it is likely that you will need more.


5. Artificial tanning from sun-ray lamps and sunbeds produce UVA and UVB rays at levels that are equal or stronger than those produced by the sun, which means they are also damaging to our skin, so it’s recommended that people avoid them.


Better than any sunscreen is to stay out of the sun and cover up.  Ideally we try to avoid sun exposure by staying in the shade, wearing wide brimmed hats and wrap around sunglasses (with UV protection)


I could not end this without posting Baz Luhrmann’s song Everybody’s Free To Wear Sunscreen

Have a great summer!

Dr. Harvey