It just takes a few minutes sitting in my garden or on a beach, and then a couple days later my skin starts peeling off.

只要在我家庭院或海灘坐上幾分鐘，幾天後，我就會開始脫皮。

It’s seriously pretty gross—not exactly the effect most people go for when they sunbathe.

真的超噁心 — 這絕對不是普羅大眾做日光浴所追求的效果。

But, what really happens when you get a sunburn?

但曬傷時，到底是發生什麼事啊？

I’m Anna Rothschild, and this is Gross Science.

我是 Anna Rothschild，這裡是《噁心科學》頻道。

Most burns occur if you come in contact with something hot, like when you scald the roof of your mouth on a slice of pizza.

大部分的燒傷在你碰觸到燙的東西時才會產生，比如說，吃比薩的時後燙到上顎。

But sunburns are actually not caused by heat.

但曬傷其實不是因為高溫而造成。

Sunlight is made up of a bunch of different types of radiation.

陽光是由一連串不同種類的光所組成。

One of them is infrared radiation, which is primarily what makes sunlight feel hot.

其中一種為紅外光，它就是讓陽光產生熱的原因。

But there’s also visible light, which allows us to see sunlight, and then there’s ultraviolet radiation.

還有可見光，它讓我們能看見陽光，另外還有紫外光。

Ultraviolet, or UV, radiation is what causes a sunburn.

紫外線，或稱 UV 光，才是造成曬傷的元兇。

It can wreak havoc on skin cells by disrupting important molecules, like DNA.

紫外線能藉由干擾皮膚細胞裡重要的分子，如 DNA，大肆破壞細胞。

So, your body does its best to protect you from it.

所以身體會盡全力保護自己。

When UV radiation hits your skin, pigments called melanin absorb it, and shield your DNA from harm.

當 UV 光照到肌膚時，黑色素會將其吸收，保護 DNA 不受其害。

Now, melanin is present in our skin cells all the time—it’s what gives your skin its particular color.

黑色素一直都存在於皮膚細胞中 — 它就是讓我們有特定膚色的原因。

It’s created by special cells called melanocytes, which then distribute the melanin to other cells called keratinocytes.

黑色素是由稱為黑色素細胞的特殊細胞製造，然後再被分配至角化細胞。

Those are the most common cells in your outermost layer of skin.

角化細胞是外層皮膚最常見的細胞。

When your skin is exposed to UV, the melanocytes ramp up their melanin production, and also transfer more melanin to the keratinocytes.

當肌膚照射到 UV，黑色素細胞就會提高黑色素的產量，並且運送更多黑色素至角化細胞。

This happens to varying degrees based on your genetic makeup, but that’s why your skin might turn darker, or tan, if you’re out in the sun for a while.

反應程度取決於你的基因組成，這就是為什麼你在太陽底下晃一會兒，皮膚就會變黑、變深。

But, the melanin defense is far from foolproof—regardless of how dark your skin is, or how much you tan, some UV rays can sneak past.

但黑色素的防禦是絕對不夠靠譜的 — 不管你本來膚色多黑、或把自己曬得多黑，有些 UV 光就是能避開這層防禦。

And when they do, they can damage your DNA.

一旦通過防護，它們就會傷害你的 DNA。

This can actually happen in a few different ways.

它傷害 DNA 的方式其實有好多種。

Sometimes the radiation will directly zap your DNA, damaging it in just a trillionth of a second.

有時紫外線會直搗 DNA ，只需要不到兆分之一秒就能造成損傷。

Alternatively, UV rays can do something more sinister—they can actually turn your melanin against you.

或者，UV 可以更邪惡一點——讓你的黑色素造反。

The radiation can make your cells produce these harmful molecules called free radicals.

紫外線可以讓細胞產生稱為自由基的有害物質。

Now, this is a little bit complicated, but essentially the free radicals excite an electron in your melanin. I'm excited!

事情有點複雜，但基本上，自由基會激發黑色素的一顆電子。我被激發了！

The melanin then bumps into your DNA and excites an electron there. I'm excited too!

被激發的黑色素碰到 DNA ，進而激發 DNA 的一顆電子。我也是！

—which can cause the DNA to kink.

——那會讓你的 DNA 變得病懨懨。

Regardless of how it happens, once your cells are damaged they start producing warning molecules, signalling that something bad is going on.

無論是怎麼發生的，一旦細胞受損，它們就會開始製造警示物質，藉此來傳送噩耗。

If enough cells produce the signal, your body will mount an inflammatory response, sending lots of different types of blood cells to the area to stop and repair the damage.

如果產生這種訊息的細胞夠多，身體就會啟動發炎反應，派出各種血球細胞到曬傷的地方，來制止並修復傷害。

And it’s this influx of blood that causes the redness you typically see with a sunburn, depending on how light your skin is.

也就是因為血液匯集，才會形成典型曬傷的發紅症狀，發紅的情況要看你的膚色有多白。

So, what about the peeling?

那麼，脫皮又是怎麼回事呢？

Well, your skin cells are shedding all the time without you noticing it.

皮膚細胞其實一直在脫落，只是你沒注意到。

You actually have stem cells in your skin that live for decades.

其實皮膚裡有幹細胞，它可以存活數十年。

The stem cells produce layers of keratinocytes, which fall off and are replaced over time.

幹細胞製造層層的角化細胞，它會隨著時間脫落及更新。

But those keratinocytes don’t mature properly when they’re damaged by UV.

但被 UV 損傷的角化細胞，它們不會正常地長大成熟。

So instead of flaking off inconspicuously, they all clump up and peel off together.

它們不會小片小片、默默地剝落；而是成群結隊，一起脫皮離開。

Now, your body actually has enzymes that repair a lot of the DNA damage caused by UV rays.

其實身體裡有些酵素，它們能修復很多 UV 光所帶來的 DNA 傷害。

But, it can’t always repair all of it.

但它不是每次都能修復所有的傷害。

And if the damage isn’t fixed in one of your stem cells, you might have a real problem.

如果其中一個幹細胞裡的傷害沒被修復，事情就大條了！

When those cells replicate, they might create a mutation at the site of the damage.

當幹細胞複製時，受傷的地方可能會發生突變。

And depending on where the mutation occurs, this could lead the cell to become cancerous sometime down the road.

根據發生突變的不同位置，之後很可能會讓細胞轉變成癌細胞。

Remember, even if you don’t tend to burn, UV radiation can damage your DNA.

記住，就算你不容易曬傷，UV 光還是會傷害你的 DNA。

So if you know you’re going to be out in the sun for a while, make sure you’re covered up or wearing sunscreen.

所以如果知道自己等等要頂著太陽外出一下，請確保把自己遮好或是擦上防曬。

For me, being outside and exploring the world is super important for my happiness, and excites my curiosity.

對我來說，在外探索世界是件超重要的樂事，它能激起我的好奇心。

But it’s way more fun to go on an outdoor adventure without coming home to disgusting peeling skin.

但如果可以出外大肆探險、回家時又不會有噁心的脫皮的話，就太完美了。

Got a question about sunburns? Let me know in the comments.

還對曬傷有問題嗎？留言讓我知道吧！

And for more gross science, hit subscribe.

按下訂閱以了解更多《噁心科學》。