Why is hydrazine/monopropellant dangerous?

• A. It is a toxic clear oily liquid with ammonia-like odor; exhaust can sicken or kill unprotected personnel. Wear full PPE and SCBA.
• B. It is an inert liquid with no odor.
• C. It is a solid at room temperature.
• D. It evaporates harmlessly.

Answer: (A)

Hydrazine monopropellant is extremely hazardous because it’s a highly toxic, corrosive liquid that can be absorbed through the skin and inhaled, leading to serious health effects or death in unprotected people. It has a clear, oily appearance and an ammonia-like odor, which can hint at its presence but should not be relied on for safety. In a spill or during combustion, toxic vapors and exhaust from the propellant can sicken or kill nearby personnel, so responders must wear full PPE and a self-contained breathing apparatus to protect against inhalation and skin exposure. The odor is not a safe signal of danger, and the substance is not inert, not solid at room temperature, and not harmlessly evaporating; its real hazard is the toxic vapor and potential for severe injury.