harmful gas

基本解释

Trees are natural air conditioners. They take harmful gas from the air, and release oxygen into the air.
树木是天然的空气净化器，他们可以吸收空气中有害的气体并向空气中释放氧气。
An Oxford-educated chemist, Margaret Thatcher would also never have claimed, as Bachmann did in 2009, “There isn’t even one study that can be produced that shows that carbon dioxide is a harmful gas.”
作为一位受过牛津大学教育的化学家，玛格丽特·撒切尔也绝不会象2009年巴克曼那样，声称“没有一个研究能证实二氧化碳是一种有害气体。”
Only for gasoline exhaust the harmful gas emissions of 10% ~ 50%.
尾气中的有害气体排放量仅为汽油的10% ～ 50%。

But because NF3 was not widely used when the Kyoto protocol was created, it is not classified and controlled as a harmful gas--so even though we've tightened the belt and reduced some emissions, we've missed new ones that are making things far worse.
FORBES: Magazine Article
In two of the most heavily drilled states in the U.S., there is no sign natural gas development has caused harmful air pollution.
FORBES: PSEHE: Where Ideology Trumps Reality
And it's really going to become harmful, to be frank, if gas prices, you know, continue to stay at the level that they are, or even rise higher.
NPR: Commuting 'Because They Have To'

有害气体
It not only wastes the coal resources, but also releases a great deal of poisonous and harmful gas, causing environmental pollution and damage to miners' health.
煤矿自燃发火不但浪费煤炭资源,而且还会释放出大量的有毒有害气体,造成环境污染,危害矿山工人身体健康。
医药科学
有害气体