Noxious vapors, also known as miasmas (7 letters) and EFFLUVIA (8 letters), are gases or particles that are released into the air and can be harmful to humans and animals. MIASMA (6 letters) is a term used to describe a noxious, unpleasant, or unhealthy smell or vapor. EFFLUVIA (8 letters) is a term used to describe a noxious gas or vapor that is emitted from a source. Both miasmas and EFFLUVIA are considered noxious vapors and can cause health problems if inhaled.