Radiation also applies to rainbows and a doctor examining an x-ray.

因為彩虹和醫生檢查用的 X 光也算輻射，

So what is radiation really, and how much should we worry about its effects?

那輻射到底是什麼，對其影響我們又該多憂心呢？

The answer begins with understanding that the word radiation describes two very different scientific phenomena: electromagnetic radiation and nuclear radiation.

答案要先從瞭解「輻射」這個詞是用來描述兩種非常不同的科學現象：電磁輻射和核輻射。

Electromagnetic radiation is pure energy consisting of interacting electrical and magnetic waves oscillating through space.

「電磁輻射」是由相互作用的電磁波所組成的純能量，透過空間振盪傳遞。

As these waves oscillate faster, they scale up in energy.

隨著這些波振盪的速度變快，它們的能量也隨之提高。

At the lower end of the spectrum, there's radio, infrared, and visible light.

在光譜的低頻端有無線電、紅外線和可見光。

At the higher end are ultraviolet, X-ray, and gamma rays.

高頻端則有紫外線 X 射線和伽瑪射線。

Modern society is shaped by sending and detecting electromagnetic radiation.

現代社會是藉由發送和檢測電磁輻射成形的。

We might download an email to our phone via radio waves to open an image of an X-ray print, which we can see because our screen emits visible light.

我們能透過無線電波把郵件下載到手機來開啟 X 光片的影像，影像之所以可見是因為螢幕發射出可見光。

Nuclear radiation, on the other hand, originates in the atomic nucleus, where protons repel each other due to their mutually positive charges.

另外一種就是「核輻射」 它來自原子核，核中的質子因為都帶正電荷而相斥。

A phenomenon known as the strong nuclear force struggles to overcome this repulsion and keep the nucleus intact.

一種現象稱為「強核力」會努力克服質子相斥，同時維持原子核的穩定。

However, some combinations of protons and neutrons, known as isotopes, remain unstable, or radioactive.

然而，某些質子與中子的組合，也就是「同位素」 依然不穩定，亦即具有放射性，

They will randomly eject matter and/or energy, known as nuclear radiation, to achieve greater stability.

會隨機放射物質和／或稱為「核輻射」的能量使自己達到較大穩定度。

Nuclear radiation comes from natural sources, like radon, a gas which seeps up from the ground.

核輻射來自大自然，例如氡，這是一種由地下向上滲出的氣體。

We also refine naturally occurring radioactive ores to fuel nuclear power plants.

我們還精煉天然的放射性礦石提供燃料給核電廠，

Even bananas contain trace amounts of a radioactive potassium isotope.

甚至連香蕉裡都含有微量的鉀放射性同位素。

So if we live in a world of radiation, how can we escape its dangerous effects?

所以我們如果生活在輻射世界裡該怎麼避免其危險與影響呢？

To start, not all radiation is hazardous.

首先，並非所有輻射都具有危害。

Radiation becomes risky when it rips atoms' electrons away upon impact, a process that can damage DNA.

當輻射撞擊出原子中的電子時才會有危險，這過程會對 DNA 造成傷害，

This is known as ionizing radiation because an atom that has lost or gained electrons is called an ion.

這種輻射就叫「游離輻射」因為原子失去或得到電子就稱為離子。

All nuclear radiation is ionizing, while only the highest energy electromagnetic radiation is.

所有核輻射都是游離輻射，而電磁輻射只有最高能量的才是游離輻射，

That includes gamma rays, X-rays, and the high-energy end of ultraviolet.

包括 γ 射線 X 射線和高能量端的紫外線，

That's why as an extra precaution during X-rays, doctors shield body parts they don't need to examine, and why beach-goers use sunscreen.

這就是為何照 X 光要做額外防護措施（醫生會遮住不需檢查的身體部位）以及為何沙灘客要擦防曬油。

In comparison, cell phones and microwaves operate at the lower end of the spectrum, so there is no risk of ionizing radiation from their use.

相較之下，行動電話和微波爐放射的是低頻光譜，所以使用上沒有游離輻射的危險。

The biggest health risk occurs when lots of ionizing radiation hits us in a short time period, also known as an acute exposure.

對健康造成最大的威脅是大量游離輻射在短時間內擊中人體時，也稱為「急性曝露」。

Acute exposures overwhelm the body's natural ability to repair the damage.

急性曝露會把人體自身的修復能力破壞殆盡，

This can trigger cancers, cellular dysfunction, and potentially even death.

這誘發癌症細胞功能障礙，甚至可能死亡。

Fortunately, acute exposures are rare, but we are exposed daily to lower levels of ionizing radiation from both natural and man-made sources.

所幸，急性曝露相當罕見，但是我們每天都曝露在來自自然界和人造物品的低劑量游離輻射下。

Scientists have a harder time quantifying these risks.

科學家很難將這些風險量化。

Your body often repairs damage from small amounts ionizing radiation, and if it can't, the results of damage may not manifest for a decade or more.

人體經常要修復由少量游離輻射造成的損害，若修復不了，損害結果可能十年或更久都不會顯現出來。

One way scientists compare ionizing radiation exposure is a unit called the sievert.

科學家用來計算游離輻射曝露量的方法是稱為「西弗」的單位。

An acute exposure to one sievert will probably cause nausea within hours, and four sieverts could be fatal.

急性曝露在一西弗下可能在數小時內出現噁心症狀，四西弗可能會致命。

However, our normal daily exposures are far lower.

然而，我們日常曝露量低得多。

The average person receives 6.2 millisieverts of radiation from all sources annually, around a third due to radon.

一般人每年從各種來源接觸的輻射量是 6.2 毫西弗，約三分之一是來自氡。

At only five microsieverts each, you'd need to get more than 1200 dental X-rays to rack up your annual dosage.

以每次照射只有 5 微西弗計為例，必須要超過 1200 次的口腔 X 光照射才能達到一年的劑量。

And remember that banana?

還記得香蕉嗎？

If you could absorb all the banana's radiation, you'd need around 170 a day to hit your annual dosage.

人體若能將香蕉的輻射劑量完全吸收，則必須一天吃 170 根香蕉才能達到整年劑量。

We live in a world of radiation; however, much of that radiation is non-ionizing.

我們雖生活在充滿輻射的世界，然而，大部分輻射都是非游離輻射。

For the remainder that is ionizing, our exposures are usually low,

其他剩餘是游離輻射的，我們的曝露量通常很低，

and choices like getting your home tested for radon and wearing sunscreen can help reduce the associated health risks.

選擇檢測家中氡氣，外出擦防曬都能幫助減少危害健康的風險。

Marie Curie, one of the early radiation pioneers, summed up the challenge as follows:

早期輻射先驅之一的瑪麗·居禮（居禮夫人）對這挑戰做了以下結論：

"Nothing in life is to be feared, it is only to be understood. Now is the time to understand more, so that we may fear less."

「生活中沒什麼可怕的事，只有需要被瞭解的事。現應當多一些瞭解，才能少一分擔心受怕。」