UN 2032 — Nitric acid, red fuming
Placard: Corrosive. ERG Guide 157. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2032 is Nitric acid, red fuming, a fuming toxic corrosive oxidizing acid assigned to ERG Guide 157. It releases red-brown nitrogen dioxide fumes and reacts dangerously with many incompatibles.
Hazard overview: EXTREMELY CORROSIVE and TOXIC red fuming nitric acid; vapor, mist or liquid contact may cause severe injury. Strong oxidizer; may intensify fire and react dangerously with fuels, organics, reducing agents and some metals. Releases dense reddish-brown nitrogen dioxide fumes that are highly toxic and may travel downwind.
Response guidance: For a UN 2032 incident, verify the product with shipping papers, container markings, SDS and ERG Guide 157. Establish incident command, isolate the area, stay upwind, control ignition or incompatibility hazards, prevent runoff or vapor spread and base entry/fire-control actions on monitoring and local SOP.
Firefighter training notes: Training for UN 2032 should emphasize red fuming nitric acid as a toxic oxidizing acid, NO2 fume behavior, Table 1 use, oxidizer segregation, water-use limits and Level A entry decisions. Use ERG 157, SDS and local SOP.
Regulatory context: Nitric acid, red fuming is regulated as a hazardous material for transportation and emergency response purposes. Storage, workplace exposure, emergency planning, spill reporting, waste handling and environmental requirements vary by exact product, concentration, quantity and jurisdiction. Verify current requirements through shipping papers, SDS, container markings and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Nitric acid, red fuming should be stored in compatible acid/oxidizer-rated containers with secondary containment, away from fuels, organics, bases, reducing agents, metals, heat and contamination. Ventilation and fume control are essential.
UN 2032 Quick Details
Common Hazards of UN 2032
- EXTREMELY CORROSIVE and TOXIC red fuming nitric acid; vapor, mist or liquid contact may cause severe injury.
- Strong oxidizer; may intensify fire and react dangerously with fuels, organics, reducing agents and some metals.
- Releases dense reddish-brown nitrogen dioxide fumes that are highly toxic and may travel downwind.
- Reaction with water, moisture or incompatible materials may generate intense heat and increase fuming.
- Contact with metals may release toxic nitrogen oxides and sometimes flammable hydrogen.
- Fire may produce irritating, corrosive and/or toxic gases.
- Runoff may be strongly acidic, oxidizing, toxic and environmentally harmful.
Chemical Identity & Physical Properties
Red-brown fuming liquid with a suffocating, acrid odor. Highly corrosive and releases reddish-brown nitrogen dioxide vapors on contact with air.
| Also known as | RFNARed fuming nitric acidNitrogen dioxide solution in nitric acidFuming nitric acid |
| CAS Number | 7697-37-2 |
| Appearance | Red-brown fuming liquid with a suffocating, acrid odor. Highly corrosive and releases reddish-brown nitrogen dioxide vapors on contact with air. |
| Flash Point | Not applicable (strong oxidizer) |
| Boiling Point | 83-86C (181-187F) |
| Vapor Density | Vapors heavier than air (>1) |
| Water Reactivity | Reacts violently with water, generating intense heat and corrosive fumes |
Fireground Response Guidance — UN 2032
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA and fully encapsulating acid-resistant chemical protective clothing for close entry or unknown concentrations. Level A may be needed because fumes are toxic, corrosive and oxidizing.
Isolation & Evacuation
First Actions for a UN 2032 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.
- Avoid breathing vapors, gas, dust, mist, smoke or fumes and avoid skin or eye contact.
- Keep fuels, organics, reducing agents, metals and combustibles away; use Table 1/protective-action guidance where applicable.
- Do not touch damaged containers or spilled/released material unless properly trained and wearing appropriate protective equipment.
- Ventilate closed spaces before entering, but only if properly trained, equipped, monitored and authorized by incident command.
- Isolate the spill or release area and expand the perimeter for fire involvement, vapor spread, dust spread, cylinder heating or unknown product identity.
- Use ERG Guide 157, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 2032 — Nitric acid, red fumingUse 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.