mephitic air

obsolete uncountable

(chemistry, obsolete) Any of various gases considered noxious to humans, including carbon dioxide and nitrogen.

Japanese Meaning

人体に有害な気体、特に二酸化炭素や窒素などの、毒性を持ち不快な影響を及ぼすガスを含む空気 / （化学分野での古い用法）人体に対して有害とされる各種ガスを含む大気

The cave filled with mephitic air, forcing the explorers to retreat before they could reach the chamber.

洞窟は有毒ガスで満ち、探検者たちはその部屋に到達する前に撤退を余儀なくされた。

Sense（1）

(chemistry, obsolete) Any of various gases considered noxious to humans, including carbon dioxide and nitrogen.