In smoggy weather, the machine would breathe in the air in front of the bike and blow out a stream of clean air toward the biker's face.

在有雾霾的天气里，机器会吸进自行车前面的空气，然后向骑自行车的人的脸上吹出一股清新的空气。

youdao

No American should have to drive out of town to breathe clean air.

任何美国人都不应非得开车出城去呼吸清洁的空气。

《柯林斯英汉双解大词典》

Physically clean the beast: Stop by the local office store, grab a can of compressed air, and clean out the "dust bunnies", especially if you can hear the exhaust fans over the mid-day football.

物理地打扫一下电脑：路过当地的办公用品商店时，顺便买一罐压缩空气，用它清除一下电脑机箱里的积尘。特别是当你觉得精疲力尽的风扇声甚至盖过了正午的足球比赛时。

youdao

It's time to replace those ideological Clean Air Act filters, get the EPA out of the climate regulation nonsense, and clear the atmosphere of corrupt Enron-legacy "green energy" and carbon-trading agendas once and for all.

FORBES: The Bell Tells For You

Lichens are sensitive to changes in their environment, and scientists use lichens as a way of finding out whether air is polluted or clean.

BBC: York & North Yorkshire - Can you help identify lichen?

On December 21, 2011, the Environmental Protection Agency carried out its obligation under the 1990 Clean Air Act and demanded that coal-fired power plants implement the available technologies to reduce their emissions by 90 percent.

FORBES: Obama Gives Green Light to New Mercury Rules