How do gas masks actually work? - George Zaidan

譯者: Mina Liu 審譯者: Alexis Young

You might think of gas masks as clunky, spooky, military-looking devices

你可能會覺得防毒面具是又厚重、 又恐怖、帶有軍事風的裝備，

only found in spy movies or World War I museums.

只會出現在間諜電影或 第一次世界大戰博物館中。

But you probably already own a mask that uses remarkably similar technology.

但是你可能已經擁有一款 技術很相近的口罩了。

And in the near future, we may need to rely on these filters

不久之後，我們日常生活

as part of our everyday lives.

可能需要依賴這些過濾設備。

In addition to emerging diseases,

除了新興疾病外，

wildfire frequency has more than tripled from 1996 to 2021.

森林大火發生的頻率在 1996 年到 2021 年之間增加了 2 倍以上。

As fires burn longer and cover more land, their smoke affects more people each year.

隨著火災燃燒時間更長、範圍更廣， 每年受煙霧影響的人數也在增加。

Climate change is also causing more hot, sunny days,

氣候變遷也帶來更多大熱天，

which accelerates the production of toxic ground level ozone.

加速了地表有毒的臭氧產生。

So, how do these masks work,

那麼，這些口罩的原理是甚麼？

and can they protect us from new and old airborne threats?

它們能保護我們免受 空氣中新舊有害物質的威脅嗎？

Well, the first rule of filters is making sure you have a tight seal.

過濾設備的首要條件是密封良好，

Without that, even the best mask in the world is useless.

不能密封，那即便是世界上 最好的口罩也是毫無用處。

So assuming your mask is on tight,

所以，假設你的口罩密封良好，

this technology can capture pollutants in one of two ways:

這項技術可以用兩種方式 來捕捉空氣污染物：

filtering them out by size or attracting specific chemical compounds.

按顆粒大小過濾， 或吸附特定的化合物。

For an example of the first approach, let’s look at wildfire smoke.

舉個第一種方法的例子， 我們來看看野火的煙霧。

When forests burn, they generate a wide variety of chemicals.

當森林燃燒會產生各種化學物質。

At close range, there are so many different pollutants

在近距離下，污染物 種類之多、濃度之高，

at such high concentrations that no filter could help you—

任何濾網都幫不了你。

this is why firefighters travel with their own air supply.

這就是為什麼消防員 需要攜帶自己的空氣補給。

But further away, the situation is different.

但在遠一點的地方，情況就不同了。

While there's still a range of chemicals,

雖然仍然有各種化學物質，

但它們大多已經凝聚成 直徑小於 2.5 微米的

they’ve mostly aggregated into tiny solid or liquid particles

smaller than 2.5 microns in diameter.

固體或液體微粒。

This particulate matter is much of what you're seeing and smelling in smoke,

這種微粒就是在煙霧中 看得到且聞得到的主要成分，

and it's especially dangerous for children, the elderly,

這對兒童、老年人，以及有呼吸道

and those with respiratory or cardiovascular diseases.

或心血管疾病的人特別危險。

Luckily, the majority of these particulates are still large enough

幸運的是，這些微粒大部分仍然夠大，

to be captured by the most basic filters,

能夠被最基本的濾網捕捉到，

which are made of polypropylene or glass strands

這些濾網由聚丙烯或玻璃纖維製成，

roughly 1/10 the width of a human hair.

大概是人類頭髮粗細的十分之一。

Under a microscope, they look like a thick forest,

在顯微鏡底下，濾網看起來 就像一片茂密的森林，

and at this scale, these branches have a special property.

而在這樣的範圍下， 這些分枝具有特殊的性質。

Typically, when you use a sieve,

通常在使用篩子時，

you’re filtering out objects larger than the sieve’s holes.

你會過濾掉比篩孔大的物體。

But these polypropylene branches can catch particles much smaller

但是這些聚丙烯分支 可以捕捉比它們的間隙

than the gaps between them.

更小得多的顆粒。

That’s because, when a particle collides with a thread,

這是因為當微粒與纖維產生碰撞時，

van der Waals forces cause it to stick as if it were made of Velcro.

凡得瓦力會讓微粒像是 魔鬼氈一樣黏在纖維上。

Plus, size-based filters can use electrically charged fibers

此外，以網孔過濾的濾網 可以用帶電的纖維

that attract particles not already on a collision course.

吸引本來不會碰到纖維的微粒。

This is how even a simple N95 mask can catch at least 95% of particulate matter.

這就是為什麼一個簡單的 N95 口罩 也可以捕捉 95％ 以上的微粒，

And why an N100 mask

以及為什麼 N100 口罩

or an air purifier with a high efficiency particulate air filter

或具有高效率空氣微粒過濾網 （HEPA）的空氣清淨機，

can catch at least 99.97% of particulates.

可以捕捉至少 99.97% 的顆粒。

With a tight seal,

加上完美密封，

this level of protection will filter out most airborne pollution.

這種保護將過濾掉大部分空氣污染。

Unfortunately, some pollutants are still too small for this approach,

不幸的是，對於某些很小的 汙染物，包括臭氧分子，

including ozone molecules.

這種方法就沒有用了

These are barely bigger than the oxygen that we need to breathe

這些污染物和我們呼吸的 氧氣大小幾乎一樣，

and exposure is associated with asthma, respiratory conditions,

而暴露於這類空污中， 會引起哮喘、呼吸道疾病，

and even premature death.

甚至早逝。

Our best chance to filter them are activated carbon masks.

活性碳口罩是我們過濾 這類極細小汙染物最好的方法。

At the microscopic level, activated carbon looks like a vast black honeycomb,

從顯微層面上，活性碳看起來 像是一個巨大的黑色蜂巢，

and it's highly microporous structure can trap tiny ozone molecules.

它極微孔徑的結構可以 捕捉到微小的臭氧分子。

But this material still needs help to capture other pollutants

但這種材料仍然需要輔助 才能捕獲其他的污染物，

like hydrogen sulfide, chlorine, and ammonia.

像是硫化氫、氯氣、和氨氣。

For these threats, we need to combine the activated carbon

要過濾這些汙染物，我們需要結合 活性碳與一些簡單的化學物質。

with some simple chemistry.

If the pollutant is acidic, we can infuse the filter with a basic chemical.

如果污染物是酸性的，那我們可以在 濾網中注入鹼性化學物質。

Then when the two meet, they react, and the gas is trapped.

當酸和鹼相遇時，他們會 引發反應讓氣體困住。

Similarly, we can use acids to trap basic pollutants.

同樣地，我們可以使用酸 來捕捉鹼性的污染物。

Even with the right mask, it's still smart to check air quality indicators

即使配戴合適的口罩，查看 空氣品質指標仍然是明智之舉，

and to stay indoors when the threat level is high.

並在危險等級高時，最好待在室內。

And just like a mask, you'll want to make sure your house is well sealed.

就像戴口罩一樣，你也需要 確保你的房子有良好地密封性。

You can do this by closing windows, turning off fans that vent outside,

你可以緊閉窗戶、關閉通風扇，

並使用配有 HEPA 濾網 的空氣清淨機，

and using HEPA filter equipped air purifiers

or their cheaper, DIY cousin, the Corsi-Rosenthal box.

或者用更便宜的 DIY 版本——

科西・羅森塔爾盒子 （Corsi–Rosenthal Box）。

Following these guidelines can help us breathe easy

遵循這些指南可以幫助我們

as we work on preventing these pollutants in the first place.

在努力預防這些污染物的 同時，輕鬆呼吸。