UN 1067 — Dinitrogen tetroxide
Placard: Toxic Gas. ERG Guide 124. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1067 is Dinitrogen tetroxide, a Class 2 toxic oxidizing gas/liquid assigned to ERG Guide 124. It is closely associated with nitrogen dioxide fumes and presents severe inhalation, corrosive and oxidizer hazards.
Hazard overview: UN 1067 presents toxic inhalation, corrosive contact and oxidizer hazards. Dinitrogen tetroxide/nitrogen dioxide fumes can injure lungs, react with water to form acids and intensify fires involving fuels or reducing agents.
Response guidance: For a UN 1067 incident, responders should confirm the product using shipping papers, cylinder markings, SDS and ERG Guide 124. Establish incident command, isolate the area, stay upwind, avoid vapor contact, use air monitoring when available and consult ERG Table 1 when applicable.
Firefighter training notes: Training for UN 1067 should emphasize toxic inhalation risk, corrosive vapor exposure, SCBA discipline, Table 1 protective actions and cylinder leak-control limitations. Common errors include relying on odor, entering low areas without monitoring, applying water to a reactive leak and selecting splash PPE without respiratory protection.
Regulatory context: Dinitrogen tetroxide is regulated as a hazardous material for transportation and emergency response purposes. Cylinder, workplace exposure, storage, reporting and environmental requirements may vary by product, quantity and jurisdiction. Responders should verify current requirements through shipping papers, SDS, cylinder markings, facility documents and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Dinitrogen tetroxide should be stored in compatible containers or cylinders in a cool, dry, well-ventilated area with toxic/corrosive gas controls, leak detection where required and segregation from incompatible materials. Protect containers from heat, corrosion, impact, valve damage and unauthorized access.
UN 1067 Quick Details
Common Hazards of UN 1067
- TOXIC and/or CORROSIVE; may be fatal if inhaled.
- Vapors are extremely irritating and corrosive to eyes, skin and respiratory tissue.
- Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite.
- Fire may produce irritating, corrosive and/or toxic gases.
- Runoff from fire control or vapor suppression may be corrosive or environmentally hazardous.
- Vapors may collect in low or confined areas depending on product and release conditions.
- Containers may rupture or rocket when heated.
- Strong oxidizer; may intensify fire and react dangerously with fuels or reducing agents.
- Reacts with water to form nitric and nitrous acids.
Chemical Identity & Physical Properties
Red-brown fuming liquid or yellowish-brown gas with a pungent, acrid odor. Exists in equilibrium with nitrogen dioxide. Liquid below 21°C (70°F).
| Also known as | Nitrogen tetroxideNitrogen peroxideNTODinitrogen tetraoxideNitrogen dioxide dimer |
| CAS Number | 10544-72-6 |
| Appearance | Red-brown fuming liquid or yellowish-brown gas with a pungent, acrid odor. Exists in equilibrium with nitrogen dioxide. Liquid below 21°C (70°F). |
| Flash Point | Not applicable (oxidizer) |
| Boiling Point | 21°C (70°F) |
| Vapor Density | 3.2 (heavier than air) |
| Water Reactivity | Reacts with water forming nitric and nitrous acids; reaction generates heat and corrosive fumes |
Fireground Response Guidance — UN 1067
Extinguishing Media
PPE Requirements
Positive-pressure SCBA is required for suspected toxic/corrosive gas exposure. Chemical-protective clothing should be selected using SDS, monitoring results, leak conditions and incident command; Level A may be needed for close entry into unknown or high-concentration vapor.
Isolation & Evacuation
First Actions for a UN 1067 Incident
- CALL 911. Then call the emergency response telephone number on the shipping paper, if available.
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Do not touch damaged cylinders, tanks, valves or released material unless properly trained and equipped.
- Avoid breathing gas, vapor, mist or fire gases.
- Many toxic or liquefied gases may spread along the ground and collect in low or confined areas.
- Ventilate closed spaces before entering, but only if properly trained, equipped and authorized by incident command.
- Isolate the spill or leak area for at least 100 meters (330 feet) in all directions.
- For highlighted materials, consult ERG Table 1 for Initial Isolation and Protective Action Distances.
- For non-highlighted materials, increase the precautionary distance downwind based on release size, weather, monitoring and incident command.
📋 Copy & Share Field Card
UN 1067 — Dinitrogen tetroxideUse for: Quick radio or face-to-face size-up. Short, structured, field-ready.
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
Use for: Quick text to command or incoming units. Fits in a single SMS.