因为二氧化碳比空气要重，纯净的二氧化碳可以使人窒息。

Carbon dioxide in pure form can asphyxiate because it is heavier than air.

youdao

二氧化碳泄漏会带来健康风险。 由于二氧化碳比空气重，因此可以在低洼地区和通风差的地区累积。

Spills would also be a health risk, since carbon dioxide is heavier than air, and so can build up in low-lying or poorly ventilated spots.

youdao

我用到“灾难性”一词，是想说二氧化碳比空气质量重，当二氧化碳形成的云层过重，空气锐减，所有下面的人都会窒息而死。

I say "catastrophic" because carbon dioxide is heavier than air, and a ground-hugging cloud would suffocate anyone it enveloped.

youdao