What’s in the air you breathe? - Amy Hrdina and Jesse Kroll

譯者: Lilian Chiu 審譯者: Amanda Zhu

Take a deep breath.

深深吸一口氣。

In that single intake of air,

在吸這一口氣的時候，

your lungs swelled with roughly 25 sextillion molecules,

你的肺部就充滿了約 25 乘以 10 的 21 次方個分子，

ranging from compounds produced days ago,

這些分子包括從幾天前

to those formed billions of years in the past.

到數十億年前生成的化合物都有。

In fact, many of the molecules you’re breathing were likely

事實上，你所吸入的那些分子

exhaled by members of ancient civilizations

很可能是古文明及後續 無數人類所吐出來的。

and innumerable humans since.

But what exactly are we all breathing?

但我們大家吸入的到底是什麼？

Roughly 78% of Earth’s atmosphere is composed of nitrogen

地球的大氣組成大約有 78% 是氮，

generated by volcanic activity deep beneath the planet’s crust.

由地殼下方深處的火山活動所產生。

The next major ingredient is oxygen, accounting for 21% of Earth’s air.

次多的成分是氧，

佔了地球空氣的 21%。

While oxygen molecules have been around as long as Earth’s oceans,

雖然地球有海洋的時候 就有氧分子了，

oxygen gas didn’t appear until ocean dwelling microorganisms

但要到海洋中的微生物 演化出生產氧氣的能力之後

evolved to produce it.

才有氧氣出現。

Finally, .93% of our air is argon,

最後，我們的空氣有 0.93% 是氬。

a molecule formed from the radioactive decay of potassium

氬是地球大氣、地殼，及地核中的鉀

經過放射性衰變產生的分子。

in Earth’s atmosphere, crust, and core.

Together, all these dry gases make up 99.93% of each breath you take.

我們吸入的空氣中， 99.93% 就是這些乾燥氣體。

Depending on when and where you are, the air may also contain some water vapor.

依據時間、地點的不同， 空氣可能也含有一些水氣。

But even more variable is that remaining .07%,

但那剩下的 0.07% 才是更多變的，

which contains a world of possibilities.

充滿各種可能性。

This small slice of air is composed of numerous small particles

空氣的這一小部分 包含了數種小型粒子，

including pollen, fungal spores, and liquid droplets,

包括花粉、真菌孢子、液態飛沫，

alongside trace gases like methane and carbon dioxide.

還有微量氣體，如甲烷及二氧化碳。

The specific cocktail of natural and man-made compounds

空氣中混有哪些天然及人造化合物，

changes dramatically from place to place.

會因地點而有很大的差異。

But no matter where you are,

但不論你身在何處，

.07% of every breath you take likely contains man-made pollutants—

你所吸入的每一口氣中有 0.07%

都可能含有人造污染物，

potentially including toxic compounds that can cause lung disease, cancer,

可能是會造成肺部疾病、癌症，

甚至損害 DNA 的有毒化合物。

and even DNA damage.

There’s a wide variety of known pollutants but they all fall into two categories.

已知的污染物有很多種， 但全都可以分為兩類：

The first are primary pollutants.

第一類是初始污染物。

These toxic compounds are directly emitted

這些有毒化合物是從人造 或天然的來源直接釋放出來的。

from a man-made or naturally occurring source.

However, they don't always come from the places you'd expect.

然而，它們的來源 不見得是你所預期的。

Some large factories mostly generate water vapor,

一些大型工廠釋放的主要是水氣，

with only small quantities of pollutants mixed in.

裡面只摻雜了少量的污染物。

Conversely, burning wood or dung can create polycyclic aromatic hydrocarbons;

相反地，燃燒木頭或糞肥 會產生多環芳香烴；

dangerous compounds that have been linked to several types of cancer,

它們是危險的化合物，

as well as long-term DNA damage.

和多種癌症和長期的 DNA 損傷有關。

In all cases, pollutants interact with regional weather patterns and topography,

不論哪一種情況，污染物都會 受各地的天氣型態及地形影響

which can keep compounds local or spread them kilometers away.

而被局限在當地 或散播至數公里之外。

When these molecules travel through the air, a transformation occurs.

在空氣中移動時，

這些分子會發生變化。

Natural compounds called oxidants, formed by oxygen and sunlight,

氧氣和陽光會形成叫做 「氧化劑」的天然化合物，

break down the pollutants.

氧化劑會分解污染物。

Sometimes, these reactions make pollutants more easily washed out by rain.

有時，這些反應會導致 污染物更容易被雨水沖洗掉。

But in other cases, they result in even more toxic secondary pollutants.

但在其他的情況下， 會產生毒性更強的衍生性污染物。

For example, when factories burn coal,

比如，工廠在燒煤時，

they release high concentrations of sulfur oxides.

會產生高濃度的硫氧化物。

These molecules oxidize to form sulfates,

這些分子會氧化，形成硫酸鹽，

which condense with water vapor in the air to form a blanket of fine particles

並與空氣中的水氣結合，

形成厚厚一層微粒子，

that impair visibility and cause severe lung damage.

降低能見度並造成嚴重的肺部損傷。

This so-called sulfurous smog was well-known in 20th century London

眾所周知在 20 世紀， 倫敦出現過所謂硫酸煙霧，

and continues to plague cities like Beijing.

後續也讓北京等城市為之所苦。

Since the advent of cars,

從汽車出現以來，

another secondary pollutant has taken center stage.

硫酸鹽汙染物的風頭 就被另一種衍生性污染物搶走了。

Exhaust from fossil fuel-burning vehicles releases nitrogen oxides and hydrocarbons

化石燃料汽車的廢氣會釋放 氮氧化物及碳氫化合物，

which react to form ozone.

它們會發生反應，形成臭氧。

And while some ozone in the upper atmosphere

雖然高層大氣中的臭氧

helps shield us from ultraviolet rays, on the ground,

能幫我們阻擋紫外線，

在地面，這類氣體可能會 和衍生性粒子一起形成，

this gas can form alongside secondary particles and create photochemical smog.

產生光化學煙霧。

This brown fog can be found covering densely packed cities,

這種褐色霧氣可能會覆蓋 人口密集的城市，

making seeing difficult and breathing hazardous.

讓視線變差，呼吸也會有危險。

It also contributes to climate change by trapping heat in the atmosphere.

它也會將熱困在大氣當中， 因而促成氣候變遷。

In recent decades, industrial activity has contributed to a huge spike

近數十年，工業活動造成

各種微量氣體的排放暴增，

in various trace gas emissions,

fundamentally changing the air we all breathe.

從根本上改變了我們所呼吸的空氣。

Many places have already responded with countermeasures.

許多地方已經有對策來因應。

Most cars produced since the 1980′s are equipped with catalytic converters

在 1980 年代製造的大部分汽車 都配有觸媒轉化器，

that reduce the emission of carbon monoxide and nitrogen oxides.

減少一氧化碳和氮氧化物的排放。

And today, places like Beijing are battling smog

現今，北京等地對抗煙霧的方式

by electrifying their energy infrastructure

是將能源基礎設施電氣化，

and limiting automobile emissions altogether.

同時限制汽車的排放。

But while moving away from fossil fuels is essential,

雖然減少化石燃料的使用 是十分重要的事，

there's no universal remedy for air pollution.

但要處理空氣污染， 沒有任何通用的補救方式。

Different regions need to respond with unique regulations

不同地區必須要用 各自適用的法規來因應，

that account for their local pollutants.

處理他們當地的污染物。

Because no matter where you live, we all share the same air.

因為不論你住在哪裡，

我們呼吸的是一樣的空氣。