Why do we have to wear sunscreen? - Kevin P. Boyd

为啥子我们要涂防晒霜 - 凯文P.博伊德(Kevin P. Boyd)

翻译人员: Danny Wang 校对人员: Bighead Ge

Most of us think of the Sun as our friend.

多数人认为阳光使我们的朋友。

It helps plants grow,

它帮助植物生长，

keeps us warm,

使我们暖和，

and who doesn't love to lie on the beach on a sunny day?

谁不希望在阳光下躺在沙滩上呢？

But for all of it's good qualities,

不过出了它的好处外，

the Sun can also be harmful in large amounts.

阳光也可以造成很多伤害。

That's why we invented sunscreen.

所以我们发明了防晒霜。

The purpose of sunscreen is to shield the body

防晒油的作用在于保护身体

from the Sun's ultraviolet rays,

免受阳光中紫外线照射

which have several harmful effects,

所带来的伤害，

including sunburn,

包括灼伤,

aging,

and skin cancer promotion.

皮肤老化，

也可引发皮肤癌。

These rays are separated

紫外线可以用

by their different wave lengths,

不同波长来区分，

into types such as UVA

可分为 UVA （长波紫外线）

and UVB,

和 UVB （中波紫外线），

which exert a variety of effects in the skin

这会对皮肤产生各种影响

due to the absorption patterns of chromophores,

这是由于色基发色团的吸收方式中，

the parts of the molecules

部分分子

responsible for their color.

对颜色产生反应。

The primary two chromophores are hemoglobin,

两种主要的色基发色团是血红蛋白，

found in our red blood cells,

存在于红学球中，

and melanin, which gives our skin its pigment.

以及黑色素，它使我们的皮肤产生色素。

We know that UVB rays cause the skin to burn.

我们知道 UVB 射线会导致皮肤晒伤。

The role of UVA rays is less well understood

而对 UVA 射线的作用的了解还不够全面

and appears to have an effect

不过会引发

on our tanning response,

照射反应，

carcinogenesis,

癌变，

and aging.

和老化。

So, how does the sunscreen protect us from these rays?

那么，防晒霜如何保护我们免受这些射线的伤害呢？

There are two basic types of sunscreen,

常用的防晒霜有两种，

physical and chemical blockers.

物理防护型和化学防护型。

Physical blockers, like zinc oxide

物理防护型，例如氧化锌

or titanium dioxide,

或二氧化钛，

reflect the Sun's rays by acting as a physical barrier.

象物理性屏障一样反射太阳射线。

If you've seen lifeguards with noses covered in white,

如果你见到过救生员的鼻子上覆盖着白色物体，

then you know what this looks like.

那么你就知道这看上去象什么了。

The same ingredients are primary components

相同的配方被用作制作婴儿用

of diaper creams,

痱子粉，

where the goal is also to create a physical barrier.

目的也在于产生物理屏障。

Historically, they haven't always been easy to apply

一直以来，他们不是那么容易涂抹

and were conspicuously visible on the skin,

而且在皮肤上也很显眼，

but new formulations have made this less of an issue.

不过新的配方减少了这些不便。

Chemical blockers, on the other hand,

另一方面，化学型防晒霜，

absorb the Sun's rays.

吸收阳光中的射线。

They deteriorate more quickly than physical sunscreens

相对物理型防晒霜更快退化

because their ability to absorb the Sun diminishes.

因为他们吸收阳光的能力会逐渐消失。

Generally, these are more transparent

一般说来，这种防晒霜更加透明

when rubbed on the skin,

当涂抹于皮肤之上，

but some people develop allergric reactions

不过有些人会对某些化学品

to some of the chemicals.

产生过敏反映。

Regardless of the type of sunscreen,

无论何种防晒霜，

all are subjected to testing

都需要经过测试

to determine their sunburn protection factor,

以衡量其防辐射系数，

or SPF.

或简称 SPF。

This is essentially a measure of the protection

这实际上是防护效果的单位

that the sunscreen will provide from UVB rays

用来衡量防晒霜能提供的对于 UVB 射线的保护

before one begins to burn.

当一个人开始受到照射时。

But even if you don't burn,

不过即便你没有晒伤，

you still need to use sunscreen

也应该使用防晒霜

because unless you live in a cave,

因为除非是居住于洞穴中，

you're not immune to the effects of the Sun.

你还是不能免于阳光的影响。

It is true that darker skinned people

事实上深色皮肤的人

and those who tan easily

和那些容易晒黑的人

have more built-in protection from sunburns,

不容易被晒伤，

but they are still vulnerable

不过他们仍然无法幸免于

to the effects of UVA.

UVA 带来的伤害。

Children under the age of six months,

六个月以下的儿童

on the other hand,

从另一方面来说，

should have almost no sun exposure

应该完全避免阳光照射

as their protective mechanisms

因为他们的保护机能

are not fully functioning,

还没有完全发育，

and their skin is more likely to absorb

另外他们的皮肤也更易于吸收

any sunscreen that is applied.

任何涂抹的防晒霜。

Wearing sunscreen helps protect

涂抹防晒霜有助于

against the development of all three types of skin cancer:

避免这三类皮肤癌：

basal cell carcinoma,

基底细胞癌，

squamous cell carcinoma,

鳞状细胞癌，

and melanoma.

以及黑色素瘤。

On a daily basis, the DNA in your cells

日常情况下，你细胞中的 DNA

is developing mutations and errors

产生的突变和错误

that are generally handled

通常都会

by machinery within your cells,

在细胞中自动处理，

but ultraviolet rays from the Sun lead to mutations

不过阳光中紫外线引发的大量变异

that the cell may not be able to overcome,

使细胞的自我修复无法承受，

leading to uncontrolled growth

导致失去控制的生长

and eventual skin cancer.

最终导致皮肤癌。

The scariest thing about this

最恐怖的事情是

is that usually you can't even see it happening

通常你根本观察不到任何事情

until its too late.

直到为时已晚。

But if these concrete risks to your health

如果这些危害健康的事实

are not enough to convince you to use sunscreen,

还是无法说服你使用防晒霜，

there are aesthetic reasons as well.

还有一个审美上的原因。

Along with cigarette smoking,

出了吸烟以外，

sun damage is the leading cause of premature aging.

阳光伤害是提早老化的主因。

Photoaging from chronic sun exposure

长期暴晒在阳光下

leads to a loss of elasticity in the skin,

会导致皮肤失去弹性，

in other words, making it look saggy.

或者说，使皮肤看上去下垂。

Take a look at this truck driver

看看这个卡车色基

who's left side was chronically exposed to the sun

他的左侧长期暴晒于阳光下

and notice the difference.

注意他们的区别。

This is an important point.

这是很重要的一点。

Car windows block UVB, the burn rays,

车窗可以隔绝 UVB，烧伤射线，

but not UVA, the aging rays.

不过挡不住 UVA，老化射线。

It is recommended to use sunscreen daily,

建议每天都使用防晒霜，

but you should pay special attention

不过你也要特别注意

before prolonged sun exposure

在长时间暴露在阳光下时

or when at the beach

或在沙滩上

or among snow

或在雪地中

since the reflectivity of water and ice

因为水和冰的反射

amplifies the Sun's rays.

会放大阳光中的射线。

For these cases, apply about an ounce

在这些情况下，于出门前十五到三十分钟前

fifteen to thirty minutes before you go out

涂抹大约一盎司防晒霜。

and once again soon after you get outside.

而且在出门后再涂抹一次。

After that, you should reapply it every two to three hours,

然后，每隔两到三小时再涂抹一次，

especially after swimming or sweating.

特别是在游泳和出汗之后。

Otherwise you should wear protective clothing

否则就应该穿上防护服

with ultraviolet protection factor, or UPF.

具有防止紫外线系数（UPF）的防晒服。

Stay in shaded areas,

尽量待在有阴凉的地方，

such as under trees or an umbrella,

例如树下或伞下，

and avoid the sun at the peak hours

避免日照强烈的时段

of 10 a.m. to 4 p.m.

如上午 10 点到下午 4 点。

And what's the best kind of sunscreen?

那么最好的防晒霜是什么呢？

Everyone will have their preference,

每个人都有自己的偏好，

but look for the following things:

不过请考虑以下几点：

broad spectra,

广谱，

SPF of at least 30,

防晒系数 SPF 至少 30，

and water-resistant.

并且防水。

A light moisturizer with SPF 30

防晒系数 SPF 30 的少量润肤霜

should be good for daily use.

就很适合日常使用。

Take note if you decide to use a spray.

如果你决定使用防晒喷雾，请记得

They take several coats to effectively cover your skin,

需要不少涂层才能有效保护皮肤，

like painting a wall with a spray can

就像在墙壁上的喷雾绘画

versus a paint brush.

同画笔绘画的区别。

So, enjoy the sun,

好，享受阳光吧，

but enjoy it with sunscreen.

不过要记得涂抹防晒霜。