Chief among them are odorless gases including nitrogen, hydrogen, methane and oxygen, with a trace amount of some other odorous gases like ammonia, hydrogen sulphide, etc.

• 其中主要成分是氮、氢、二氧化碳、甲烷、氧等无臭气体，以及微量的氨、硫化氢、等形成臭味的气体。