There are four primary agents that could possible be used in a chemical attack:

• Lung-damaging or choking agents
• Blood agents
• Blister agents
• Nerve agents

Others that might be used include: incapacitating agents, riot-control agents, heavy metals, volatile toxins, pesticides, dioxins, explosive nitro compounds and oxidizers, flammable industrial gases and liquids, plus corrosive industrial acids and bases.