Volatile Organic Compounds (VOCS), as one of the major sources of air contaminations, can not only cause direct pollution, but also lead to secondary pollution, such as photochemistry smog.

作为空气污染的主要来源之一，易挥发有机物(VOCS)不仅是一次污染源而且还可能造成光化学烟雾等二次污染。

youdao

Well, direct ones are pollution directly from factories, refineries, waste treatment plants etc, aren't they?

额，直接污染源是那些从工厂、精炼厂、污水处理厂排放出来的污染，是吗？

youdao

Air pollution hasn't gone away, but these PBX RIGS have been replaced just about everywhere by direct-dial phone lines and computerized call-routing systems.

空气污染一直没有消失，但是这些专用分组交换机却已经被全被直拨电话和计算机化的路由呼叫系统替代了。

youdao

Although he cannot definitely rule out a direct effect by the pollution on the birds' metabolism of the yellow pigment, or its incorporation into their feathers, the correlation between a shortage of caterpillars and faded plumage is strong evidence of a link between pollution, diet and bird colour.

ECONOMIST: Great tits

The numbers for air pollution are several steps removed from direct measurements.

FORBES: 5 Caveats About The Autism And Air Pollution Study

The story beginning overleaf assesses the implications for marine biodiversity of transgressing planetary boundaries, due to human-induced changes to the climate system, pollution and ocean acidification, as well as more direct threats like invasive species, overfishing and habitat destruction.

UNESCO: Open Access to Scientific Information