miasma n., pl. miasmata or miasmas [Gk. stain, defilement, pollution.] 1. An exhalation of vapor emanating from marshy ground or rotten matter which, it used to be believed, causes diseases such as malaria. During yellow fever epidemic at Saint Louis, people were advised to go up on to the terraces at night to avoid the miasmata and breathe pure air (Suret-Canale 1971:404). 2. A thick vapor-like atmosphere or emanation. The room, apparently a den of disreputable characters, was pregnant with the miasma of marijuana smoke. 3. A pervasive, corrupting atmosphere or influence. It is a disturbing story and it tells us something of the miasma of power, the ease with which people in power can act barbarously in relation to individuals… (Ben Okri in West Africa 1982).
From Word Dictionary of Foreign Expressions