By+David+Shukma

提到空氣污染，我們最直觀的感受就是霧霾天氣。近幾年來，中國霧霾天愈演愈烈，最嚴重時，中國的半壁江山都陷入“霾伏”，對人們的健康構成威脅。事實上，空氣污染已經(jīng)是一個國際性的問題，只是各地的形成原因與機理各不相同，需要我們有針對性地研究與治理。本文就介紹了英國的科學家如何從微觀與宏觀角度研究空氣污染的狀況并提出治理措施，或許能夠給我們些許啟示。

A London primary school may issue face-masks to its pupils. The council in Cornwall may take the extreme step of moving people out of houses beside the busiest roads.

Four major cities—Paris， Athens， Mexico City and Madrid—plan to ban all diesels1） by 2025.

Stuttgart， in Germany， has already decided to block all but the most modern diesels on polluted days.

In Indias capital， New Delhi， often choked with dangerous air， a jet engine may be deployed2） in an experimental and desperate attempt to create an updraft3） to disperse dirty air.

The World Health Organization calculates that as many as 92% of the worlds population are exposed to dirty air—but that disguises the fact that many different forms of pollution are involved.

For the rural poor， it is fumes4） from cooking on wood or dung indoors.

For shanty5）-dwellers in booming mega-cities， it is a combination of traffic exhaust， soot6） and construction dust.

In developed countries， it can be a mix of exhaust gas from vehicles and ammonia7） carried on the wind from the spraying8） of industrial-scale farms.

In European cities， where people have been encouraged to buy fuel-efficient diesels to help reduce carbon emissions， the hazard is from the harmful gas nitrogen dioxide9） and tiny specks10） of pollution known as particulates11）.

The first step is to understand exactly where the air is polluted and precisely how individuals are affected—and the results can be extremely revealing.

Personal Data

Scientists at the University of Leicester are trailling a portable air monitor to gather precise data at a personal scale.

We watched as volunteer， Logan Eddy， 14， carried the device in a specially adapted backpack that recorded details of the air he was exposed to.

Exactly where he walked was then displayed as lines on an electronic map， the colour of those lines conveying how unhealthy the air was at different points.

It was much worse than WHO guidelines where he had waited to cross a busy junction12）， strikingly cleaner in a side-street but then almost off the scale in a sheltered spot beside an arcade13） of shops where a car was parked with its engine idling.

Seeing a graphic display of how pollution can vary so dramatically changed Logans view of air， and his friends adjusted their behaviour immediately.

“The people who found out have stopped waiting right near the buses after school for their friends，” he says. “Theyve been waiting … further away from the buses. Its obviously had an impact on them.”

The personal monitor is one of a range of devices being deployed in Leicester to build up a detailed picture of where pollution hotspots form—and when.

In many cases， they can be short-lived， appearing during rush-hours when traffic jams develop.

For Prof Roland Leigh， of Leicester University， understanding precisely where and when vehicles slow to a crawl or stop will help manage the flow of traffic in a way that minimises the impact on the most vulnerable people—the young and the elderly.

“One of the things we can all do is to improve our transport systems so that our congested traffic is not queued up outside of primary schools and old peoples homes but instead is queued in other parts of the city where theres going to be less harm，” he says.

Cleaning Up the Engine

But what about tackling one of the main sources of the problem in the first place， the vehicles spewing14） out the pollutants？

In Europe， under pressure from regulators， the manufacturers have progressively cleaned up their engines over the past few decades—first to trap carbon monoxide15） and unburned fuel， then particulates and most recently nitrogen dioxide.

The latest European standard， Euro 6， requires vehicles to emit far less pollution than older models， but trust has inevitably been eroded after the car giant VW was caught cheating16）—using software that activated the emissions controls only during tests.

At Bath University， engineers use a “rolling road” and a robotic “driver” to put cars through realistic simulations of how they are normally used， to find out exactly whats released from the exhaust pipe17）.

They are also working to understand the trade-offs involved in cleaning up an engine.

For example， adding more pollution-trapping devices can add to fuel consumption， which means increased emissions of carbon dioxide， undermining efforts to tackle climate change.

And however good the latest standards， they still leave vast numbers of older vehicles out on the roads.

Hence the idea of a national scrappage18） scheme—to provide incentives to drivers to switch to a cleaner model.

Its attracting growing support from an unlikely coalition including the Federation of Small Business， London First， Greenpeace and the Licensed Taxi Drivers Association.

The challenge， as ever， is to find the money to make this happen and to agree who should pay—taxpayers through government incentives or the vehicle owners themselves.

Prof Chris Brace， an automotive engineer of Bath University， says， “Whichever way you approach it， you are asking people to spend more in taxation or more to buy new vehicles， and we need to decide whether thats something were comfortable with as a society.”

Some awkward choices lie ahead.

Will the parents of an asthmatic19） child dig deep in their pockets to switch to a cleaner car？

Will new housing developments include charging points for electric cars？

Will the money saved from a fuel-efficient diesel be seen as worth sacrificing for the sake of better air for everyone？

And bear in mind that these are “First World” questions.

In the rapidly growing cities of Africa， and many parts of Asia， there is hardly any monitoring of pollution at all， let alone political will or money to tackle it.

倫敦的一所小學或許會給該校學生發(fā)放口罩?？滴譅柨さ牡胤轿瘑T會或許會采取極端措施，將居所位于繁忙道路旁的人遷移出去。

巴黎、雅典、墨西哥市、馬德里這四大主要城市計劃在2025年前禁止一切柴油車。

在德國，斯圖加特市已經(jīng)決定，出現(xiàn)嚴重污染的天氣時，禁止除最新型號以外的一切柴油車出行。

印度首都新德里常常為有害氣體所籠罩。在無計可施的情況下，該市或?qū)⒄{(diào)用噴氣發(fā)動機，試驗看能否產(chǎn)生向上的氣流驅(qū)散不潔的空氣。

據(jù)世界衛(wèi)生組織計算，全球多達92%的人口暴露在不潔的空氣中，但這一數(shù)字掩蓋了一個事實，即空氣污染有多種不同的類型。

對鄉(xiāng)村的窮人來說，污染是燃燒木柴做飯或室內(nèi)的糞便產(chǎn)生的有害氣體。

對繁華大都市中的棚戶區(qū)居民來說，污染是交通廢氣、油煙以及建筑灰塵的混合體。

在發(fā)達國家，污染氣體就是汽車尾氣和氨氣的混合。給大型農(nóng)場噴灑農(nóng)藥后氨氣隨風傳播。

歐洲城市鼓勵人們購買節(jié)能型柴油車，以降低碳排放。對這些城市來說，危險來自有害的二氧化氮氣體和被稱作顆粒物的小粉塵污染物。

首要的措施是準確了解哪里的空氣遭到了污染，以及人們是如何受到影響的——得出的結果很能說明問題。

個人數(shù)據(jù)

萊斯特大學的科學家正在跟蹤一個可攜帶空氣監(jiān)測器，以準確收集個人層面的數(shù)據(jù)。

我們觀察的對象是14歲的志愿者羅根·艾迪。他用特制的背包裝著這個裝置，記錄周圍空氣的詳細數(shù)據(jù)。

他走過的地方都會以線條的形式精確地顯示在一個電子地圖上。這些線條的顏色表示了不同地點空氣的不健康程度。

當他在擁擠的交叉路口等候通過時，所處位置的空氣質(zhì)量要嚴重低于世界衛(wèi)生組織的指標;在小街道時，空氣則異常干凈;當位于室內(nèi)商場旁邊的頂棚下面，旁邊還停著一輛發(fā)動機空轉(zhuǎn)的小汽車時，所處位置的空氣差得幾乎爆表。

看了污染情況如何大幅變化的圖示后，羅根改變了對空氣的看法。他的朋友也立刻改變了習慣。

“了解這一情況的人，放學后再也不會在大巴附近等朋友了，”他說道，“現(xiàn)在會在遠離大巴的地方等。顯然，這對他們是有觸動的?！?/p>

萊斯特大學使用了多種裝置來繪制一份詳細的圖示，展示污染高發(fā)區(qū)形成的地點和時間。個人監(jiān)測器是其中之一。

很多情況下，這類高發(fā)區(qū)在高峰期交通擁堵時形成，存在時間可能很短。

萊斯特大學的羅蘭·利教授認為，準確了解車輛減速慢行或者停車的時間和地點將有助于管理車流，使之對幼兒和老人這些弱勢群體所造成的影響降到最低。

“改善交通系統(tǒng)是我們都能做的一件事情。這樣，擁堵就不會在小學或老年人的住所旁發(fā)生，而是在城市的其他地區(qū)，在那里，危害會少一些。”他說。

凈化發(fā)動機

不過，先來解決污染問題的主要根源之一——排放污染物的汽車，如何？

在歐洲，生產(chǎn)商們迫于監(jiān)管部門的壓力，在過去的幾十年里大幅凈化了各自生產(chǎn)的發(fā)動機：先是控制一氧化碳和未燃燒的油料，之后是顆粒物，最近又開始控制二氧化氮。

最新的歐洲標準“歐六”規(guī)定，汽車的廢氣排放量需遠低于舊型汽車。但在汽車巨頭大眾公司的作弊行為曝光之后，這種信任也不可避免地遭到了質(zhì)疑。大眾利用軟件使排放控制在測試時才會啟動。

巴斯大學的工程師們利用一個“滾動道路”和一個機器人“司機”來模擬汽車在現(xiàn)實環(huán)境中的正常使用，以此查明汽車廢氣的確切成分。

他們也在研究凈化發(fā)動機過程中需要權衡的方方面面。

比如，過多的污染截留裝置將增加油料消耗，也就意味著二氧化碳的排量將會增加，進而破壞了為應對氣候變化所做的工作。

并且，不管最新的標準多么好，都管不了路上大量的老式汽車。

因此，有人想到了全民報廢舊車計劃，旨在激勵駕駛員換用更加環(huán)保的車型。

這一想法獲得的支持越來越多。小企業(yè)聯(lián)盟、“倫敦第一”組織、綠色和平組織以及執(zhí)業(yè)出租車司機協(xié)會都支持這一想法，盡管這些機構之間并不大可能結成聯(lián)盟。

這一想法同樣面臨著一個挑戰(zhàn)，即如何獲得所需的資金以及誰應該為此買單：是納稅人以政府激勵措施的形式承擔，還是由車輛所有人自行承擔。

巴斯大學汽車工程師克里斯·巴拉斯教授說：“不管哪種方法，都是要求人們交更多的稅或花更多的錢來購買新車。我們需要搞明白，我們整個社會對此是否樂意。”

我們會面臨一些尷尬的選擇。

孩子患有哮喘，其父母是否還愿意花錢換成更加環(huán)保的汽車？

開發(fā)新房屋時是否會配置電動汽車充電樁？

為了讓人人都能享受更好的空氣，是否值得放棄本可通過使用節(jié)能柴油車節(jié)省下來的錢？

要清楚，這些還都是“第一世界”的問題。

在快速發(fā)展的非洲城市以及亞洲的許多地區(qū)，連對污染的監(jiān)測都幾乎為零，更不用提應對污染的政治意愿或經(jīng)費了。

1. diesel [?di?z（?）l] n. 柴油車，內(nèi)燃機車

2. deploy [d??pl??] vt. 有效地利用;調(diào)動

3. updraft [??pdrɑ?ft] n. 上升氣流，向上排氣

4. fume [fju?m] n. （難聞且常為有害的）煙，氣體

5. shanty [???nti] n. 棚屋，簡陋小屋

6. soot [s?t] n. 煤煙灰;煙垢

7. ammonia [??m??ni?] n. 氨;氨水

8. spray [spre?] vt. 噴灑（液體）

9. nitrogen dioxide：二氧化氮

10. speck [spek] n. （粉末狀物質(zhì)的）微粒

11. particulates [pɑ?（r）?t?kj?l?ts] n. [復] （尤指燃料燃燒時產(chǎn)生的）顆粒，微粒

12. junction [?d???k?（?）n] n. （公路的）交叉路口;（公路或鐵路的）匯合處，樞紐站

13. arcade [ɑ?（r）?ke?d] n. 室內(nèi)（購物）商場

14. spew [spju?] vt. 噴出，放出，涌出

15. monoxide [m??n?ksa?d] n. 一氧化物

16. 指2015年曝光的大眾“排放門”事件。2015年9月18日，美國環(huán)境保護署指控大眾汽車所售部分柴油車安裝了專門應對尾氣排放檢測的軟件，可以識別汽車是否處于被檢測狀態(tài)，繼而在車檢時秘密啟動，從而使汽車能夠在車檢時以“高環(huán)保標準”過關，而在平時行駛時，這些汽車卻大量排放污染物，遠超法定標準。

17. exhaust pipe：排氣管

18. scrappage [?skr?p?d?] n. （尤指舊車的）報廢; 報廢量

19. asthmatic [?s?m?t?k] adj. 哮喘（性）的;氣喘引起的