Understanding SPF: The Science Behind Sunscreen

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Transcript

Have you ever wondered what your sunscreen's SPF actually means and how much it matters? Or argued with a friend about it? Let me show you how to win that argument. But let's rewind for a second and review how sunburns happen. Think of your skin as a special bucket. A sexy bucket. Now imagine sunlight as water that can fill that special bucket. And as soon as the bucket overflows, you start to burn. If you've got light skin, that bucket is more like a shot glass. The darker your skin, the bigger the bucket. Don't clip that out of context. The size of your bucket is called your minimum erythema dose, or MED. That's only half of the equation. The stream of water coming from the sun varies on time of day, time of year, closest to the equator, and atmospheric conditions. An overcast winter morning in Canada is like a leaky faucet. High noon in Ecuador is like my old Monster X-L Super So how does sunscreen fit in? It basically turns your bucket into a bag of holding. A Hogwarts chest with an extension charm. A Mary Poppins bag for you really not nerdy folks. The SPF number is your bucket expansion factor. SPF 15 means that you can take 15 times the amount of UVs. in your bucket before it overflows. Double the SPF, double how much UV it can take. The official sunscreen test takes a patch of skin, measures how much UV energy it takes before it burns, then applies sunscreen and does it to another patch. If it takes 15 times the UV energy to get the same burn, that's SPF 15. SPF stands for sun protection factor. But that test is carried out with an amount of sunscreen equal to 2 milligrams per square centimeter of skin. I'll cover how much that is in the next video.

Additional notes

Now who can tell me the difference between SPF 30 and SPF 45? #sunscreen #sunscreenscience #skincare #skin #skinhealth #edutok #science

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