Understanding What Sunscreen Does and Doesn’t Do

I don’t know about the weather where you live but here in Western Washington where I live we’ve seen record high temperatures and more than enough sun to last us all summer (yes, there are plenty of us here in Washington bemoaning the lack of rain). With all this sun, we’ve already seen our fair share of sunburn and this is because many people still don’t understand what sunscreen is and what it does.

Let’s start with the basics. SPF stands for Sun Protection Factor. The Sun Protection Factor number is telling you how much longer you can stay out in the sun than you could if you weren’t wearing any sunscreen at all. An SPF of 15, for example, is letting you know that, if you normally can stay out in the sun for 30 minutes without sunburn or damage to your skin, with SPF 15 sunscreen you will be able to stay out 15 times longer, that is to say 7.5 hours. Increase the SPF to 30 and you should be okay for 15 hours. SPF 15 blocks 93% of the UVB rays which means that out of every 100 photon bombarding your skin 93 will be blocked while 7 will get through. SPF 30 blocks 97%.


Sounds pretty logical and straightforward, right? Not really! The problem is that most of us don’t really apply the sunscreen properly. Most of us, according to a numerous studies, only apply 1/5 to 1/2 of the amount that the manufacturer recommends (After all, we reason, of course they want me to apply lots of sunscreen, that way they can sell more!). If you apply only 1/5 of the amount of sunscreen with a protection factor of 15, you end up with a protection of only 3 rather than 15 so that now, instead of being able to stay out in the sun for 7.5 hours you will now begin to suffer damage to your skin after only 1.5 hours.

Additionally, while you may not suffer sunburn which happens because of UVB, your skin can still suffer damage (which can cause skin cancer, aging, leathering, sagging and more) if the sunscreen doesn’t protect from UVA as well. Make sure that your sunscreen contains zinc oxide, avobenzone, titanium dioxide, ecamsule and oxybenzone for maximum protection.

Three more items of note… First, don’t rely on sunscreen if you don’t have to. Short exposures to the sun are best. Sun does provide our bodies with Vitamin D which is necessary for health so try to get some exposure but keep it under 30 minutes. If you absolutely must stay out in the sun, apply sunscreen. Secondly, be aware of the fact that sunscreen does deteriorate over time and that the sunscreen you purchased last year isn’t going to protect you as well this year and certainly not as well next year. Thirdly, don’t go tanning. Tanning will prematurely age your skin and expose you to harmful UV rays. A tan, which most people associate with health is actually the opposite. Brown skin is skin that is already damaged.