在《清洁空气法案》强制要求美国使用无铅气体的二十年里，铅在世界范围内的累积量显著下降。
In the twenty years that the Clean Air Act has mandated unleaded gas use in the United States, the lead accumulation worldwide has decreased significantly.
谬论八：无碳房屋是对付建筑物温室气体排放的最佳选择。
Myth 8: zero carbon homes are the best way of dealing with greenhouse gas emissions from buildings.
氡是一种自然产生的放射性惰性气体，它无色、无味、无臭。
Radon is a chemically inert, naturally occurring radioactive gas without odour, colour or taste.
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