Toxicity (Ammonia Fuel)

Ammonia toxicity is the dominant safety hazard of ammonia as a marine fuel: NH3 is acutely toxic by inhalation, with a NIOSH IDLH of 300 ppm, an OSHA permissible exposure limit of 50 ppm over 8 hours, and an ACGIH threshold limit value of 25 ppm. Exposure above 300 ppm can be fatal within minutes, and the gas is corrosive to eyes, skin, and the respiratory tract. This drives the safety case for ammonia bunkering and dual-fuel engines: gas-detection, water-spray mitigation, double-walled piping, exclusion zones, and a quantitative risk assessment, since the leak hazard is human toxicity rather than the fire risk that governs LNG.