导读:大家都是提尘色变，然而最新研究发现灰尘减少空气质量反而变差，这是为什么呢？
Airborne dust is normally seen as an environmental problem, but the lack of it is making air pollution over China considerably worse.
空气中的灰尘通常被视为一个环境问题，但缺乏灰尘反而会对中国的空气污染造成相当严重的影响。
A new study suggests less dust means more solar radiation hits the land surface, which reduces wind speed.
一项新的研究表明，较少的灰尘意味着更多的太阳辐射到达地面，这降低了风速。
That lack of wind in turn leads to an accumulation of air pollution over heavily populated parts of China.
风力不足会反作用导致中国人口稠密地区空气污染的积累。
The researchers found that reduced dust levels cause a 13% increase in human-made pollution in the region.
研究人员发现，该地区减少的灰尘水平导致人为污染上升13％。
Hundreds of millions of people across China continue to be impacted by air pollution from factories and coal-fired power plants.
全国数以万计的人们将继续受到工厂和燃煤电厂空气污染的影响。
Studies suggest that the dirty air contributes to 1.6 million deaths a year, about 17% of all mortalities.
研究表明，受到污染的空气每年造成160万人死亡，约占死亡人数的17％。
But this new research says that the human-induced pollution is being made worse or better by naturally occurring dust that blows in from the Gobi desert.
但这项新的研究表明，由戈壁沙漠吹来的天然的灰尘正在使得人类造成的污染变得更糟或更好。
Using models to simulate 150 years of wind and dust patterns in the region, the researchers found that the dust deflects significant amounts of sunlight.
研究人员利用模型来模拟该地区150年的风沙模式，发现灰尘会减少大量的阳光照射。
Without it, more heat from the Sun hits the land. Differences in the temperatures between land and sea cause the winds to blow. Without the dust, the land warms up more and that changes the temperature differential with the sea leading to weaker breezes - and more air pollution.
没有它，来自太阳的更多的热量会到达地面。 陆地和海洋之间的温差导致风的产生。没有灰尘，地表温度上升，与海洋的温差变小，导致只能产生微弱的风，这样就导致更严重的空气污染。
"There are two dust sources. One is the Gobi and the other is the highlands of north-west China, but we found the Gobi had much more influence," said lead author Yang Yang, from the Pacific Northwest National Laboratory in Washington State, US.
华盛顿州太平洋西北国家实验室的杨杨告诉我们:“有两个灰尘的来源，一个是戈壁，另一个是中国西北的高地，但我们发现戈壁的影响力更大。”
"Less dust in the atmosphere causes more solar radiation to reach the surface. It weakens the temperature difference between the land and the sea and impacts the circulation of the winds and causes a stagnation over eastern China and that causes an accumulation of air pollution."
“大气中的灰尘减少导致更多的太阳辐射到达地面，削弱了陆地和海洋之间的温差，影响了风场循环，造成了华东地区的空气不流通，导致空气污染不断积累。
The decreases in dust emissions are considerable, varying by almost a third. The impact on winds speeds are quite small by comparison.
灰尘的排放量已经大大减少，减少了约三分之一。相比之下，对风速的影响却相当小。
However, when this takes place on a large scale over a wide region, the small change in speed means a 13% increase in the amount of air pollution over eastern China during the winter.
但是，当这个现象大面积发生的时候，风速这点微小的变化意味着在冬天华东地区的空气污染量增加了13％。
Another study has recently shown a link between declining Arctic sea ice and a major air pollution event in China in 2013.
另外一项研究表明最近北极的冰面不断减少与2013年中国大气污染事件有一定联系。
The authors of the new study believe that both theories could be true.
这个研究的作者认为，这两种理论都是有道理的。
"Our study has the same mechanism: the weakening of winds causes more pollution, and what is behind this needs to be studied," said Yang Yang.
杨先生说：“我们的研究讲述的是同样的机制：风速的减弱导致更多的污染，而更深层的原因需要进一步研究。”
"We have two views on this kind of weakening of wind. They found the sea ice, we found the dust-wind interaction can also lead to weakening of the wind. I think both of them are important."
“我们从两个不同角度看风速变弱的原因。他们从冰面减少角度入手，而我们发现灰尘与风的相互作用也可能导致风速的减弱，我认为这两者都是重要的。”
The researchers believe that the study may inform broader questions about how natural and human-created aerosols interact.
研究人员认为，这项研究可能会引发关于天然尘埃和人造污染物相互作用的更多的问题。
Many parts of the world, in addition to China, are now suffering from increased levels of air pollution and understanding how dust, winds and emissions work together may help limit some of the worst impacts of dirty air.
除了中国以外，世界上许多地方现在正在受到愈加严重的空气污染的影响，知道尘埃、风和污染物如何一起产生作用有助于减少污染空气产生的一些最严重的影响。
One of the key lessons from this study is that the absence of dusty conditions could mean the air you are breathing is worse for you, not better.
这项研究主要告诉我们，没有尘埃可能意味着你呼吸的空气更糟，而不是更好。
"Dust emissions can impair visibility, but they are not so harmful in terms of air quality." said Prof Lynn Russell from the Scripps Institution of Oceanography in California.
加利福尼亚斯克里普斯海洋学研究所的林恩·罗素教授说：“除尘可以增加可见度，但是尘埃并不是那么影响空气质量。”
"If it’s not a dusty year, you may be happy and spending more time outdoors because you don’t have this dust in the way, but you are actually going out to spend more time in more toxic air."
“如果现在不是尘土飞扬，你可能会感到幸福，愿意花更多的时间在户外，因为不会浸没在尘埃之中，但其实你在有害的空气之中停留了更长的时间。”
The study has been published in the journal Nature Communications.
该研究已发表在杂质“Nature Communications”上。
