Chemical warfare agents are classified according to their physiological affects—choking, blood, blister, nerve, irritating—or their military designation. In the case of choking agents, the classification is based on the physiological affect. Phosgene (CG) and chlorine (Cl) are two chemicals that have been used as military agents, but both are commercially available and could be obtained and used by terrorists.

General indicators of chemical preparation/production that responders should look for can include:

• Patients experiencing unexplained blisters, rashes, or welts
• Odors out of character for the surroundings
• Glassware such as flasks, beakers, test tubes, canning jars, etc.
• Improvised ventilation systems
• Cooling devices such as ice baths, refrigerators, coolers with condensers, etc.
• Heating devices such as hot plates, electric skillets, burners, etc.
• Filtration systems and materials
• Used personal protective equipment

Chemical agents are hazardous materials classified using general categories know as:

• Toxic Industrial Chemicals
• Chocking Agents
• Blister Agents (aka vesicants)
• Blood Agents
• Nerve Agents
• Riot Control Agents (aka irritants)