Sunscreen
Let's Know Things
Colin Wright
4.8 • 593 Ratings
🗓️ 12 July 2022
⏱️ 23 minutes
🧾️ Download transcript
Summary
This week we talk about SPF, UV, and the FDA.
We also discuss oxybenzone, bemotrizinol, and bisoctrizole.
Show notes / transcript: https://letsknowthings.com/episode320
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Transcript
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| 0:00.0 | UV, in the context of physics and the weather is an acronym for ultraviolet radiation, which is present in sunlight |
| 0:23.1 | and makes up a relatively small amount of the total electromagnetic radiation output of the sun, |
| 0:28.6 | about 10% of it most of the time. |
| 0:31.6 | These figures vary quite a bit throughout the day though, in different parts of the world, |
| 0:35.6 | and depending on local weather conditions. |
| 0:37.9 | But in general, a small portion of sunlight is ultraviolet in nature, and it's divided between |
| 0:43.1 | UVA, UVB, and UVC types, which impact surfaces they strike in the atmosphere and down |
| 0:50.3 | on the ground in somewhat different ways. UVA radiation plays a role in the formation of |
| 0:55.3 | skin cancer in entities with skin, including humans, while also penetrating fairly deep into |
| 1:01.6 | the skin, which is why it plays a significant role in skin aging and wrinkle formation, alongside |
| 1:07.2 | other skin changes. Very little UVA radiation is blocked by the atmosphere. |
| 1:13.6 | UVB radiation plays a more substantial role in the development of skin cancers than UVA, |
| 1:19.6 | and is also responsible for sunburns. But fortunately, most of it, most of the time, is blocked by the atmosphere. |
| 1:26.6 | Though most can mean different things depending on the time of day, most of the time, is blocked by the atmosphere, though most can mean different things |
| 1:29.6 | depending on the time of day, the weather, the altitude, and where you are in the world. |
| 1:34.9 | There's also a UVC type of ultraviolet radiation, but fortunately, we don't really need |
| 1:40.2 | to worry about this down on Earth as the atmosphere completely absorbs it. |
| 1:45.0 | Sunlight generally carries about 500 times more UVA, the deep penetrating kind of UV, than UVB, |
| 1:54.0 | which is kind of a good thing because UVB is a lot more likely to trigger the mutations that manifest as skin cancer, including the really |
| 2:02.1 | gnarly, deadly kind. But both are not great for us, in the sense that they can trigger |
| 2:06.9 | cellular mutations, can cause painful burns, and tend to prematurely age our skin in a variety |
| 2:13.8 | of ways that are generally not considered to be ideal for health and for aesthetic reasons. |
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