Tear gas is a general term for a group of chemical irritants, known as riot control agents, which are widely used by law enforcement for crowd dispersal. These substances work by rapidly causing pain and irritation to the eyes, respiratory system, and skin, forcing temporary incapacitation. When people ask if tear gas is flammable, they are often asking about the cloud of irritant itself, but the answer is nuanced. The chemical agent is not the primary fire risk; instead, the danger of ignition and extreme heat lies almost entirely within the device used to deploy it. Clarifying this distinction is important for understanding the real-world hazards associated with its use.
The Chemical Definition of Tear Gas
The active ingredients in riot control agents are not true gases but are generally solid compounds at room temperature. The most common agents, like chlorobenzalmalononitrile (CS) and chloroacetophenone (CN), are actually fine powders or microscopic particles. These agents are intentionally designed to be dispersed as an aerosol, a cloud of solid particles suspended in the air, to irritate the mucous membranes.
The pure chemical agents themselves possess high thermal stability, meaning they are not easily combustible in the way that organic solvents or paper are. For example, CN has a melting point near 58 to 59 degrees Celsius and a boiling point above 244 degrees Celsius. This physical property ensures the chemical does not spontaneously ignite or burn under normal conditions.
The chemical agent’s solid state requires a specialized mechanism to turn it into an effective, breathable cloud. Since the agent will not simply evaporate, it must be rapidly heated to vaporize or sublime into tiny particles that irritate the skin, eyes, and lungs. This necessary step of generating intense heat is what introduces the flammability hazard into the equation.
The Real Fire Hazard: Dispersion Systems
The true risk of fire and extreme heat comes from the pyrotechnic system housed within the tear gas canister or grenade. Since the solid chemical agent must be converted into an aerosol cloud, the canister contains a pyrotechnic charge designed to generate intense heat. This charge is a mixture of various chemicals, including a fuel and an oxidizer, which ignite upon activation.
Common pyrotechnic mixtures often include a starter composition, such as a blend of charcoal and an oxidizer like potassium nitrate, to initiate the burn. The main smoke-generating mixture then contains fuel, such as sucrose (sugar), and a powerful oxidizer like potassium chlorate to sustain the reaction. This mixture rapidly burns within the canister, generating the necessary heat to vaporize the solid chemical agent into a breathable irritant cloud.
This pyrotechnic reaction is, by its nature, highly flammable and generates significant heat, often reaching temperatures high enough to melt the canister’s casing or cause it to fragment. The chemical process is essentially a controlled, contained burn designed to heat the agent and create a dense smoke for dispersion.
Practical Safety Concerns and Risks
The extreme heat generated by the pyrotechnic dispersion system creates several significant dangers far beyond the chemical irritation. Canisters and grenades are known to become intensely hot, posing a direct threat of severe thermal burns to anyone who touches or is near the device.
The superheated canister also presents a serious risk of igniting secondary materials in the environment. When deployed, the burning device can land on and set fire to combustible objects such as clothing, upholstered furniture, dry grass, or other organic materials. This is how a riot control agent, which is not inherently flammable, becomes the indirect cause of a structure fire or a widespread blaze in dry conditions.
Furthermore, the rapid combustion within the container can cause the metal casing to fail under pressure. This can result in the device exploding or fragmenting, turning the canister into shrapnel that can cause severe impact injuries. The danger is compounded when the device is fired into confined spaces, where the high concentration of the aerosol and the heat-related risks are amplified.