In general, ambient air contains millions of particles, and the concentration is especially high on heavy traffic roads and in industrial areas.

一般来说，空气中夹杂着大量的颗粒物，在交通繁忙以及重工业地区其浓度最高。

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The river forms the division between the heavy industrial and light industrial areas of the city.

这条河成了这座城市重工业区和轻工业区的分界线。

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The environmental programs will certainly open up long-standing splits between legislators from industrial states and those from suburban-heavy areas more sympathetic to cracking down on pollution.

CNN: Commentary: Big risks if Obama acts boldly on budget