The physical state of DM is a light yellow to green crystalline solid. It has no pronounced odor, but is irritating. DM as a solid forms no appreciable vapor; DM was disseminated as an aerosol for tactical operations.
Symptoms are irritation of the eyes and mucous membranes, viscous discharge from the nose similar to that caused by a cold, sneezing and coughing, severe headache, acute pain and tightness in the chest, nausea, and vomiting. DM has no irritant effect on the skin. The effects of DM for moderate concentrations last about 30 minutes after exposure. At high concentrations the effects may last up to one hour.