Nitrogen
noun, の adjective
An element that can cause a person to suffocate is nitrogen. Too much or too little will cause it.
ちっそ
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
飛行機のタイヤには窒素が入っています。
There’s nitrogen in airplane tires.