n.a toxic mixture of gases (including carbon dioxide and carbon monoxide and nitrogen) after an explosion of firedamp in a mine
英汉双解大词典
afterdamp/ˈɑːftəˌdæmp/
1.
N（名词）
a poisonous mixture of gases containing carbon dioxide, carbon monoxide, and nitrogen formed after the explosion of firedamp in coal mines 爆后气体 → see also whitedamp