Why cities should plant more trees

為何城市要多種樹？

CHINA
中國

Search Google Earth for China and you'll see this.
在Google地球搜尋中國，你會看到這個。

But an unedited satellite photo might look more, like this.
但如果是沒有編輯的衛星雲圖，看起來會是這樣。

That grey smudges air pollution and it's coming from Chinese cars factories and power plants.
中國的汽車排放、工廠和發電廠造成灰色大片的嚴重空氣污染。

But it's not only here.
但不僅止於中國。

ITALY
義大利

In cities around the world, air pollution is a big problem.
空氣汙染在全世界的城市裡都是個嚴重的問題。

A majority of humans now live in cities, and that number is only going to rise, which means more cars, more factories, and more power plants.
現今大多數人都生活在城市，而那數量只會持續上升。代表更多的汽車、工廠、發電廠。

INDIA
印度

As officials explore options for fighting air pollution, there's one tool that's often overlooked-Trees. 
種植樹木－在官方研究解決空氣污染的方案裡，經常被忽略。

Cities are centers of Industry, but the resulting pollution is filling our lungs and making us sick.
城市被工廠圍繞，但這也導致我們吸了滿滿廢氣而生病。

PARTICULATE MATTER
懸浮微粒

One major culprit is particulate matter.
其中一個罪魁禍首是懸浮微粒。

Airborne particles of dust soot and smoke that are released when we burn fossil fuels or kicked up during construction and farming.
當我們燃燒化石燃料或進行施工、農業活動，會使灰塵與煤煙釋放到空中。

Ｗhen we inhale them， they can cause asthma．
當我們吸入那些雜質，會造成氣喘。

Ａnd they can also enter our bloodstream to cause strokes and even death
它們也可能會進入血管而造成阻塞，甚至死亡。

Experts estimate that outdoor air pollution kills over 3 million people a year.
學者估計每年有超過3百萬人因受室外空氣污染而死亡。

And as cities grow, leaders are funding creative and often expensive solutions for the problem.
隨著城市的成長，領導者需要募集有創意，且通常昂貴的方法來解決問題。

LONDOＮ
倫敦

In London, the mayor spent over a million pounds spraying city streets with an adhesive that was supposed to glue pollutants to the road.
在倫敦，市長花費上百萬在街道上噴灑黏著劑，希望可以把路上的空汙黏住。

“The Smog Free Tower”
空氣淨化塔

And in the Netherlands, designers have created a giant air purifier they call the smog free tower which is cool.
在荷蘭，設計師創造了一個巨大空氣清淨機，人稱空氣淨化塔，非常新穎。

But there's another simpler solution.
但其實有更簡單的解決方式。

A new report from the Nature Conservancy shows that planting trees could be a cost-effective way to improve public health, which they do in two ways.
根據大自然保護協會的最新報告，種數是最符合成本效益的方法來改善健康。它有兩個作為：

First, a tree removes particulate matter when polluted air blows through its branches.
第一，當空污被吹至樹枝，樹木可以消除懸浮粒子。

The particulate matter settles on the leaves, and when it rains, the dust is washed down the gutters so we don't inhale it.
當懸浮粒子落在樹葉上，雨水可以洗淨他們，避免人類吸收進體內。

Second, trees cool temperatures by providing shade and releasing water through photosynthesis, which cools summer temperatures by about 2 to 4 degrees Fahrenheit.
第二，樹蔭與光合作用所產生的水氣可以達到降溫，讓夏天至少減少華氏2-4度。

But there is the catch.
但樹木也有它的限制。

Trees can only clean and cool the air within a closed radius about 100 feet, so city officials need to be careful where they plant.
官方單位需要特別注意種樹的位置，因為樹只能淨化冷卻10英尺半徑內的空氣範圍。

Officials can maximize pollution reduction by planting trees were population density and air pollution overlap.
官方單位可以在人口密集度高、空汙嚴重的地方種樹，以最大化減少污染。

Washington, DC
華盛頓, DC.

The Nature Conservancy report uses data from Washington DC to create a map showing where planting trees will have the highest return on investment.
大自然保護協會運用華盛頓DC所提供的資訊，創造出一個地圖；可以看出在哪種樹的成本效益較高。

In some trees work better than others.
有些種類的樹特別有效。

Field maple/Common elm
楓樹/榆樹

Trees with larger stickier leaves, like maples and Elms, are more effective, but they also need to be considered within a larger ecosystem.
例如楓樹和榆樹，具有較大與更有黏性的樹葉效果更好，但是同時也生存於更大的生態系統。

Compared to DC, many cities around the world have even more to gain from planting trees.
與華盛頓相比，其他國家的城市在種植樹木獲得了更多成效。

This map shows where return on investment is highest for reducing particulate matter.
這張地圖顯示哪些地方在減少懸浮粒子有最高的投資報酬。

With proper targeting, planting trees can be just as cost effective as other strategies like converting public transportation to use less diesel fuel.
若目標明確，種樹與其他策略同樣能達到成本效益，譬如呼籲搭乘大眾交通工具來降低柴油使用率

But there is one major limiting factor, water access.
但水資源為其中最大的限制因子 

Boston, Annual precipitation:43.77 in.
波士頓，年降水量: 43.77英吋

What might work in Boston will be less feasible in a city like Doha Qatar, where water is a scarce resource.
在波士頓可行的計畫若在缺少水資源的多哈城市可能就行不通

And on top of that, many mayor's don't yet think of trees as a public health resource.
除此之外，許多市長還不覺得種樹為公共衛生資源

Trees might not look like giant air filters, but that's exactly what they are.
樹木其實就是巨大的空氣淨化器儘管它們看起來不像

And the sooner we start thinking of them that way, the sooner the air we breathe might be cooler and cleaner in cities around the world.
當我們越早體悟到這個道理，全世界城市裡的空氣將會越清新

 

Copyright Announcement: The above videos are  from the official Youtube channel of the organization. Why cities should plant more trees https://www.youtube.com/user/voxdotcom . The videos we selected are all publicly available on the official channel, and we do not own the copyright of these videos. Our work on Chinese translation for this film is free for the 1.2 billion audiences in Mandarin Chinese around the world to watch and learn SDGs and SROI advertising campaigns.