Although they don't cause brain damage directly, some of the chemicals in them are asphyxiants.
尽管它们不会直接引起大脑损伤，但其中的一些化学物质会令人窒息。
英语百科
Asphyxiant gas
（重定向自Asphyxiant）
An asphyxiant gas is a nontoxic or minimally toxic gas which reduces or displaces the normal oxygen concentration in breathing air. Breathing of oxygen-depleted air can lead to death by asphyxiation (suffocation). Because asphyxiant gases are relatively inert and odorless, their presence in high concentration may not be noticed, except in the case of carbon dioxide (hypercapnia).