The FDA has approved 16 active ingredients that protect against UV radiation.

美国食品及药物管理局已批准的防护紫外线的有效成分有16种。

UV radiation isn't the only way to damage cells, though, right?

紫外辐射并不是导致细胞损伤的唯一方式。

Sunlight contains three types of UV radiation, including one that never quite gets through our atmosphere.

阳光中有三种 UV 射线，其中有一种无法穿透大气层。

But exposure to UV radiation could prematurely age your hands and even potentially boost your risk of skin cancer.

但紫外线的辐射会使你的手提前老化甚至还有可能增加你患皮肤癌的风险。

The Sun makes life on Earth possible, but too much exposure to its UV radiation damages plant and animal DNA.

太阳让地球上的生物能够存活，但过量的紫外线辐射会损害植物和动物的 DNA。

But at the time when life began, the UV radiation on Earth's surface was likely too harsh for life to survive there.

但在生命开始的时候，地球表面的紫外线辐射过于强烈以至于生命无法在那里生存。

Added UV radiation reaching the planet may create a scenario where darker skin becomes an evolutionary advantage, as it protects against UV damage.

深色的皮肤可能会成为进化的优势，因为它能保护皮肤免受紫外线伤害。

Well, actually, because of some chemicals in that lime and UV radiation from the sun, your skin is about to get attacked.

事实上，由于酸橙中的某些化学物质和太阳中紫外线的作用，你的皮肤将会被伤到。

We divide the UV radiation in sunlight into three main types, based on their wavelength.

我们根据波长将阳光中的紫外线辐射分为三种主要类型。

Narrator: The FDA has approved 16 active ingredients that protect against UV radiation.

旁白：美国食品和药物管理局批准了 16 种可防止紫外线辐射的活性成分。

It filters out more than 90 percent of the harmful UV radiation coming from the sun.

它过滤掉 90% 以上来自太阳的有害紫外线辐射。

To protect themselves from UV radiation, they fabricate a defense chemical that blocks UV rayswith an outstanding efficiency.

为了保护自己免受紫外线辐射，他们制造了一种防御化学物质， 可以非常有效地阻挡紫外线。

And more solar UV radiation reaches the earth's surface. More people will get skin cancer.

更多的太阳能辐射到达地球表面。更多的人会得皮肤癌。

And despite all those expensive marketing campaigns, the best way to fight off wrinkles might just be blocking UV radiation to protect your cells from damage in the first place.

抛开昂贵的市场竞争不看，抗皱的最好方法可能就是防 UV 射线，让皮肤远离外界伤害啦。

With the energy from the UV radiation in sunlight, furanocoumarins can undergo a chemical reaction and bind to certain bits of DNA inside another creature's cells, messing with the DNA's structure.

在阳光中紫外线辐射作用下，呋喃香豆素就会发生化学反应，并且将少量的的某些DNA植入另一种生物细胞内，破坏这些DNA的结构。

But scientists later realized that these compounds can release chlorine that reacts with ozone molecules in the atmosphere, depleting the Earth's ozone layer, which protects us from UV radiation from the sun.

但科学家后来意识到，这些化合物可以释放氯，与大气中的臭氧分子发生反应，从而消耗地球的臭氧层，而臭氧层保护我们免受太阳紫外线辐射。

Its called gamma decay, and it releases electromagnetic radiation similar to visible light, or UV radiation, but higher on the energy scale.

它被称为伽马衰变， 它释放出类似于可见光或紫外线辐射的电磁辐射，但能量等级更高。

But, if you expose your cells to too much UV radiation, DNA damage can build up faster than it can be fixed.

但是，如果您将细胞暴露在过多的紫外线辐射下， DNA 损伤的累积速度可能会快于修复速度。

Perhaps eventually we could see life re-emerging slowly as traits, such as reduced oxygen-concentration concentration requirements and increased cellular resistance to UV radiation evolve via natural selection and mutation in both plants and animals.

也许最终，我们可以看到生命慢慢地重新出现，通过自然选择和动植物的突变，降低了对氧气浓度的要求，增强了细胞对紫外线辐射的抵抗力。

Plastic is basically just a long chain of molecules, and when it's exposed to sunlight, UV radiation starts to break that chain down into smaller molecules like methane and ethylene, in a process called off-gassing.

塑料是由一长串分子组成的，当阳光照射塑料时，紫外线会将分子链分解成更小的分子，比如甲烷和乙烯，这个过程叫做脱附。