Sunscreen Explained: What SPF Really Means



I overheard a conversation the other day about sunscreen and it was hard for me not to squeeze myself into it and throw some truth bombs on the situation.



I'll be honest, I used to be super ignorant about sunscreen and those 3 little letters attached to every bottle (SPF), and I used to think that the higher the SPF number, the better protected I was from the sun's rays. I'm starting to learn that a lot of people think/thought the exact same thing, though. And seriously, it's a pretty legit sounding thing; it makes sense, right? But let's find out the real info about SPF, how sunscreens actually work, and why a high SPF number often creates a false sense of security.


What is SPF?

SPF stands for sun protection factor. SPF is a measure for how long you can be exposed to the sun without reddening or sunburn compared to not applying sunscreen at all.


Is a higher SPF more protective than a lower one?

Not really. A higher SPF just means you can be out longer without re-application. So, for example, SPF 10 means you get 10x the length of protection than you would if you didn't have any sunscreen on at all. And SPF 30 means you get 30x the length of protection than you would if you didn't have any sunscreen on at all. An SPF 10 would need to be reapplied sooner than an SPF 30.


What's the difference between UVA and UVB rays?

UVB rays are often associated with the upper layer of your skin (the epidermis). These are the rays that cause sunburn and reddening, and can lead to some of the most common skin cancers with long-term or repeated exposure. UVA rays are longer and can penetrate to the lower levels of your skin (the dermis). UVA rays are the rays that primarily cause you to tan, but this tanning of the skin is actually a sign towards the damaging of your DNA. The skin changes color to try and protect from further damage, but long-term exposure to tanning can lead to cell mutations that lead to skin cancer. This is why a broad spectrum sunscreen is so important! It helps combat both types of rays.


But It's Not Quite That Simple

No sunscreen is proven to protect against 100% of rays, and factors that impact the length of time you can go without reapplication include sweating, swimming, time of day, geographical location, and wavelength distribution changes, etc. So, you may not get a full 10x length of protection you'd expect from an SPF 10 or 50x length of protection you'd expect from an SPF 50.


Additionally, there are lots of sunscreens out there loaded with toxins and chemicals (retinal palmitate, oxybenzone, parabens, octinoxate, homosalate, octocrylene, octisalate, avobenzone) which somewhat defeat the purpose of applying sun protection altogether. According to the EWG (Environmental Working Group), these ingredients have been studied, and there's a staggering concern that they cause allergic reactions, birth defects, hormone disruptions in both men and women (endocrine, thyroid, reproductive hormones/fertility, etc.), and cancer. Learn even more about these harmful ingredients here.


So what do we do?

I went to the dermatologist recently because I have a very high level of abnormal skin growths/cells that (thanks to my dumb decisions in my youth), if not looked after, have a greater potential of turning into skin cancer. My dermatologist told me that the best protection over sunscreen is wearing clothes/hats that cover your skin and finding shade when you can. If you are going to spend time in the sun, it's really important to wear a healthy, chemical-free broad spectrum sunscreen for the duration of your time outside, and reapply often. Low level sun exposure does have some benefits, but I recommend being super mindful about it.


Let me know if this blog helped you understand SPF and sunscreens a little bit better!



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