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辐射真的危险吗 – 译学馆
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辐射真的危险吗

Is radiation dangerous? - Matt Anticole

Light up the world
【启点字幕组】辐射真的危险吗
一提到辐射二字
When we hear the word radiation,
我们很容易联想到巨大的爆炸和可怕的物种变异
it’s tempting to picture huge explosions and frightening mutations,
但这仅是它涵盖的一小部分
but that’s not the full story.
无论是彩虹
Radiation also applies to rainbows
还是医生检查时所用的X光皆是辐射
and a doctor examining an x-ray.
所以辐射到底是什么
So what is radiation really,
以及如何正确看待它的影响呢
and how much should we worry about its effects?
我们应该先了解辐射一词
The answer begins with understanding that the word radiation
它描述了两种不同的科学现象
describes two very different scientific phenomena:
电磁辐射
electromagnetic radiation
核辐射
and nuclear radiation.
前者是纯粹的能量
Electromagnetic radiation is pure energy
由电波和磁波
consisting of interacting electrical and magnetic waves
在空间里交互变化产生
oscillating through space.
随着电磁波振荡频率的增高
As these waves oscillate faster,
其能量也会增大
they scale up in energy.
在光谱中低频的一端是无线电波
At the lower end of the spectrum, there’s radio,
红外线
infrared,
以及可见光
and visible light.
而光谱中高频的一端即紫外线
At the higher end are ultraviolet,
X射线
X-ray,
以及伽马射线
and gamma rays.
现代生活离不开电磁辐射的发射与探测
Modern society is shaped by sending and detecting electromagnetic radiation.
通过无线电我们可以在手机上接收电子邮件
We might download an email to our phone via radio waves
点开一张X光片
to open an image of an X-ray print,
而手机屏幕发出的可见光让我们可以看见其影像
which we can see because our screen emits visible light.
而核辐射则
Nuclear radiation, on the other hand,
始于原子核内
originates in the atomic nucleus,
带正电荷的质子相互排斥
where protons repel each other due to their mutually positive charges.
而强核力这一存在
A phenomenon known as the strong nuclear force
束缚着质子之间的斥力
struggles to overcome this repulsion
从而形成完整的原子核
and keep the nucleus intact.
然而一些质子和中子的组合
However, some combinations of protons and neutrons,
即同位素
known as isotopes,
却不那么稳定
remain unstable,
或具有放射性
or radioactive.
他们会随机地射出物质或能量
They will randomly eject matter and/or energy,
以达到更为稳定的状态
known as nuclear radiation,
这就是所谓的核辐射
to achieve greater stability.
核辐射源于自然界中的资源
Nuclear radiation comes from natural sources, like radon,
例如从地面释放出的氡气【氡衰变时产生的射线和短寿命衰变产物对人体健康具有危害作用】
a gas which seeps up from the ground.
我们也提炼自然出现的放射性矿石
We also refine naturally occurring radioactive ores
作为核电站的燃料
to fuel nuclear power plants.
甚至香蕉也含有痕量的放射性钾同位素【痕量:指极小的量】
Even bananas contain trace amounts of a radioactive potassium isotope.
所以如果我们身处充满辐射的世界
So if we live in a world of radiation,
应该如何避免它所带来的危害
how can we escape its dangerous effects?
首先 不是所有的辐射都是有害的
To start, not all radiation is hazardous.
当电子碰撞离化原子时才具有危险性
Radiation becomes risky when it rips atoms’ electrons away upon impact,
这个过程能损伤DNA
a process that can damage DNA.
这就是所谓的电离辐射
This is known as ionizing radiation
因为原子失去或得到电子后被称作离子
because an atom that has lost or gained electrons is called an ion.
所有的核辐射都是电离辐射
All nuclear radiation is ionizing,
而对于电磁辐射 只有最高能量的部分才是电离辐射
while only the highest energy electromagnetic radiation is.
包括伽马射线
That includes gamma rays,
光射线
X-rays,
以及高能量一端的紫外线
and the high-energy end of ultraviolet.
这就是在照X光时要额外警惕的原因
That’s why as an extra precaution during X-rays,
所以医生会对不需要检查的身体部分进行屏蔽防护
doctors shield body parts they don’t need to examine,
也说明了为何去沙滩的人得抹防晒霜
and why beach-goers use sunscreen.
相较而言 手机 微波等处在光谱低能量部分的
In comparison, cell phones and microwaves operate at the lower end of the spectrum,
则没有电离辐射的危险
so there is no risk of ionizing radiation from their use.
而最危害我们健康的是短时间内
The biggest health risk occurs when lots of ionizing radiation
大量的电离辐射击中我们
hits us in a short time period,
即急性照射
also known as an acute exposure.
急性照射影响了身体的本能 使其无法修复损伤
Acute exposures overwhelm the body’s natural ability to repair the damage.
从而引发癌症
This can trigger cancers,
细胞功能障碍
cellular dysfunction,
甚至有可能死亡
and potentially even death.
幸运的是 急性照射十分罕见
Fortunately, acute exposures are rare,
但我们每天都暴露在低程度的电离辐射下
but we are exposed daily to lower levels of ionizing radiation
源头可以是自然界 也可以是人为制造
from both natural and man-made sources.
科学家们花费了更多功夫来量化这些低程度电离辐射的风险
Scientists have a harder time quantifying these risks.
你的身体经常修复由小量电离辐射带来的损伤
Your body often repairs damage from small amounts ionizing radiation,
即使身体无法修复
and if it can’t,
这些损伤的后果十几年内也可能不会显现出来
the results of damage may not manifest for a decade or more.
科学家们用来比较电离辐射照射效果
One way scientists compare ionizing radiation exposure
的单位叫做希沃特(希)
is a unit called the sievert.
1希的急性照射在数小时内可能会造成恶心反胃
An acute exposure to one sievert will probably cause nausea within hours,
而4希能致命
and four sieverts could be fatal.
可是 我们日常受到的辐射是相当低程度的
However, our normal daily exposures are far lower.
平均每人每年总共
The average person receives 6.2 millisieverts of radiation
受到6.2毫希的辐射【1000毫希等于1希】
from all sources annually,
大约三分之一来自于氡
around a third due to radon.
牙齿X光一次仅有5微希辐射的量
At only five microsieverts each,
你需要给牙齿拍超过1200次X光
you’d need to get more than 1200 dental X-rays
才能达到你每年受到的辐射量
to rack up your annual dosage.
还记得之前提到的香蕉吗
And remember that banana?
假如你能吸收来自香蕉的所有辐射
If you could absorb all the banana’s radiation,
你需要每天吃大概170根才能达到每年的辐射量
you’d need around 170 a day to hit your annual dosage.
虽然我们生活的世界充满辐射
We live in a world of radiation.
但大多数的辐射并非电离辐射
However, much of that radiation is non-ionizing.
而剩余的那些电离辐射
For the remainder that is ionizing,
照射在我们身上的往往很少
our exposures are usually low,
并且我们可以选择居住经过氡气检测的房屋
and choices like getting your home tested for radon
和涂抹防晒霜
and wearing sunscreen
来减少相关的健康危害
can help reduce the associated health risks.
早年的辐射先驱居里夫人
Marie Curie, one of the early radiation pioneers,
面临此境时曾总结如下
summed up the challenge as follows:
生活里没有可怕的东西 只有需要理解的东西
“Nothing in life is to be feared, it is only to be understood.
而现在正是让去我们理解更多害怕更少的大好时机
Now is the time to understand more, so that we may fear less.”

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