The study on elemental speciation in airborne particulate matter (PM) is important for its evaluation of toxicity and source of pollution.

大气颗粒物中元素的种态研究，对评价其毒性和污染来源等有很重要的意义。

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The harmfulness and source of the particulate matter in indoor air are introduced.

作者介绍室内空气中颗粒物的危害与来源。

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In the developed world, the greatest source of particulate matter is from diesel engines.

CNN: Air pollution kills, but deaths can be prevented

This will allow truckers to reduce emissions significantly (diesel emissions include nitrous oxides, particulate matter, and other air toxics and they are a major source of pollution in some areas).

FORBES: Acceleration of the Natural Gas Highway