香港如何识别看不见的尾气排放？

This is Scientific American's 60-second Science, I'm Christopher Intagliata.

这里是科学美国人——60秒科学系列，我是克里斯托弗·因塔利亚塔。

Air pollution causes millions of premature deaths around the world every year, according to an estimate by the World Health Organization.

据世界卫生组织估计，空气污染每年导致全球数百万人过早死亡。

And one of the most significant drivers of air pollution in cities is exhaust that comes out of tailpipes from cars, trucks and buses.

城市空气污染最主要的驱动因素之一是汽车、卡车和公共汽车排气管中的废气。

In an effort to tame its air pollution, the city of Hong Kong has deployed a system that can sense when a high polluting vehicle drives by.

为了缓解空气污染，香港市已经部署了一种系统，当高污染的车辆驶过时，该系统可以感知到。

There are more than 150 sites for monitoring of vehicle emissions in Hong Kong, so that high-emitting vehicles can be identified quickly and enforced for repair.

香港有超过150个监测车辆排放的地点，以便迅速找出排放严重的车辆，并强制进行维修。

John Zhou is an environmental engineer at the University of Technology Sydney.

约翰·周(John Zhou)是悉尼科技大学的环境工程师。

He's co-author on a new analysis of the program, in the journal Science Advances.

他是发表在《科学进步》杂志上的一篇关于该项目的新分析的合著者。

He says the system works like this.

他说这个系统是这样运作的。

Sensors at road level shoot beams of light across the road, to a reflector.

道路上的传感器发射光束穿过道路，到达反射器。

The sensors measure how much light is absorbed by pollutants, and roughly calculate emissions from passing vehicles.

这些传感器可以测量污染物吸收了多少光，并大致计算出过往车辆的排放量。

The system simultaneously reads license plates, and sends notices to big polluters.

该系统同时可以读取车牌号，并向大型污染车辆发送通知。

Enforcement began in 2014.

执法始于2014年。

In the following four years, the program pulled 16,000 vehicles off the road—mostly taxis, but also private cars and buses.

在接下来的四年里，该项目让16000辆汽车停靠路边，其中大部分是出租车，但也有私家车和公交车。

Government subsidies helped fix up 96 percent of those vehicles, and ensured they passed smog tests.

政府补贴帮助修复了其中96%的车辆，并确保它们通过了雾霾测试。

You know, hopefully, from the publication of this research, we can raise awareness about the effectiveness of getting the heavy polluting vehicles off the road.

希望通过这项研究的发表，我们可以提高人们对让重污染车辆远离道路的有效性的认识。

The repairs cut pollutants like carbon monoxide and nitrogen oxides from the city's air.

车辆维修减少了城市空气中的一氧化碳和氮氧化物等污染物。

And that spared people from breathing them in.

这就避免了人们吸入污染物。

But the repairs had another effect too.

但维修工作还有另一个影响。

By reducing pollution from the tailpipe, we're also simultaneously increasing the performance of fuel combustion in vehicles.

通过减少尾气污染，我们同时也提高了汽车的燃料燃烧性能。

So it's indirectly contributing to the reduction of fuel.

所以这间接地减少了燃料。

And therefore, the reduction of greenhouse gases such as carbon dioxide.

因此，二氧化碳等温室气体减少了。

By cleaning up its air, Zhou says Hong Kong has cut carbon emissions too.

周表示，通过净化空气，香港也减少了碳排放。

That's a win-win for people in the city—and beyond.

这对城市内外的人们来说是双赢的。

Thanks for listening for Scientific American's 60-second Science. I'm Christopher Intagliata.

谢谢大家收听科学美国人——60秒科学。我是克里斯托弗·因塔利亚塔。