ABSTRACT
Agents can be solids, liquids, or gases. They may be colorless when pure but are often colored from yellow to black due to impurities. Most agents have poor warning properties and are usually only identifiable at concentrations that are much greater than is considered safe. These properties may also be masked by the presence of impurities or solvents that are used to facilitate dissemination. However, exposed individuals may report the following odors:
Vapors from most agents have a relative density that is greater than air, tend to remain close to the ground, and collect in low places. Many agents are absorbed into porous materials, including painted surfaces, and these materials could continue to emit vapor after the initial incident. The persistency of agents released inside a building is dramatically increased over agents that are released in the open environment.
