In my last post I discussed the difference between UVA and UVB rays. All you need to remember is UVA is the aging ray, makes up 98% of the ultraviolet radiation from the sun, and has a longer wavelength which allows it to penetrate into the deeper skin layers. UVB is only 2% of the sun’s ultraviolet rays, responsible for sunburns, and has a shorter wavelength which means it only affects the top layers of skin.
During the winter many people quit wearing sunscreen. There’s a belief that sunscreen is only used to prevent sunburns.
This philosophy is pretty entrenched though. The first sunscreen was developed by Franz Greiter in 1938. It was called Glacier Cream and had an SPF of 2. It doesn’t sound like a lot but it blocks half the sun’s rays which is still quite a bit.
If you want to know how much it fails to block the equation is simple: (1 / SPF).
I still don’t like it. SPF 35 fails to block 1/35th of the sun’s rays…………. why not do something more simple or tell us how much it blocks. Like the PA system I reviewed when reviewing UVA versus UVB rays. The average public just doesn’t think like that.
To calculate what percent of UV rays are blocked you need the following equation: 100%[1 – (1 / SPF)].
It isn’t a hard equation but I’m not a mathematical genius who can do that math in my head shopping down the sunscreen aisle. And I’m not pulling out a calculator. So here’s a cheat sheet
SPF 50 blocks 98%
SPF 30 blocks 97%
SPF 20 blocks 95%
SPF 15 blocks 93%
SPF 10 blocks 90%
SPF 5 blocks 80%
SPF 2 blocks 50%
What you see is a pretty swift drop off after SPF 10. Dermatologist recommend an SPF 30-35 be used daily. Based on one survey most people who apply sunscreen daily only apply 25% of the necessary amount to reach that SPF. So if we’re applying only 25% of an SPF 30 we’ve only applied an effective SPF 7.5 which is in that drop off area.
Why we apply sunscreen in the winter?
If you live in the northern hemisphere we are getting ready to enter winter, in the southern hemisphere you’re exiting winter. In some areas we’ve already entered winter (Montana is already covered in 4 feet of snow).
Because of the earth’s axis and how it wobbles is why we have seasons. As a result it’s also why we have less direct sunlight in the winter and are less likely to get a sunburn. But remember the UVB (burning rays) is only 2% of the total UV radiation that we come in contact with. 98% is the UVA radiation that causes premature aging. So even though we are less likely to get a sunburn we are still coming into contact with a massive amount of UVA (aging) radiation.
That’s getting a broad spectrum sunscreen with UVA and UVB protection is so important. Both UVA and UVB can cause cancerous/ precancerous cells. That’s why skin experts harp on it so much. I myself have two spots I have to watch on my back where I routinely missed sunscreen and I’ve been an avid sunscreen user since my 20s (I was NOT in my teens).
The only sunscreens that offer UVA protection have either zinc oxide, titanium dioxide, or avobenzone. All of those ingredients offer both UVA/UVB protection so they can be used alone. Octocrylene offers some UVA protection but not enough to make it worth purchasing. Therefore if your sunscreen only has octocrylene in it, throw it out and get something with zinc oxide, titanium dioxide, or avobenzone.
Avobenzone has been in the controversy circle because of a small series of studies that combined the active ingredient with chlorine to simulate a pool scenario and found that avobenzone broke down into chemicals that could be carcinogenic. Those studies had several flaws in it and it can’t be extrapolated to real world scenarios. At this time avobenzone receives a score of low risk even from EWG and they are incredibly strict.
Pregnant women and women looking to get pregnant…….. it might be good to avoid avobenzone and only use zinc oxide because avobenzone has not been thoroughly tested on those individuals.
Hopefully everyone is going to start wearing sunscreen year round!! Don’t forget your hands either. When grabbing the steering wheel you have full exposure to those UVA and UVB rays.
My Sunscreen Favorites
My favorite sunscreen for my face is Shiseido’s WetForce SPF 50+ PA++++. As someone who wears a minimal amount of makeup my sunscreens are on full display. This doesn’t form a white hazy cast, there’s plenty of moisturizing properties to keep my face hydrated, and it stays on even when I’m sweating.
If you want your sunscreen to have a slight tint, there is a tinted Wetforce SPF 50+ PA++++ or Shiseido Anessa Sunscreen Skincare Milk that’s also an SPF 50+ PA++++. The Anessa line is less expensive but still gives excellent sun protection while being sweatproof. Those are my personal favorites.
I’m a big fan of SPF 50. The technology has changed drastically over the last decade that has lightened up the SPF50. If you know you know. SPF50 use to be very heavy and cakey. Now we have light, quick dry formulas that make it easier to use that higher SPF and protect that skin a little more.