UN 1939 — Phosphorus oxybromide, solid
Placard: Corrosive. ERG Guide 137. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1939 is Phosphorus oxybromide, solid, a corrosive toxic phosphorus halide solid assigned to ERG Guide 137. Moisture can generate heat and hydrogen bromide/phosphoric acid fumes.
Hazard overview: UN 1939 presents water-reactive corrosive fumes, toxic dust/vapor, molten burn and acidic runoff hazards. Keep the material dry and use compatible dry agents.
Response guidance: For a UN 1939 incident, responders should verify the product with shipping papers, package markings, SDS and ERG Guide 137. Establish incident command, isolate the area, stay upwind, control ignition or incompatibility hazards, prevent runoff or vapor spread and choose entry/fire-control actions based on monitoring, SDS and local SOP.
Firefighter training notes: Training for UN 1939 should emphasize exposure routes, air monitoring, PPE selection, decontamination, runoff containment and ERG/SDS verification. Use ERG 137, SDS and local SOP.
Regulatory context: Phosphorus oxybromide, solid is regulated as a hazardous material for transportation and emergency response purposes. Transportation, workplace exposure, spill reporting, waste handling, storage and environmental requirements may vary by formulation, concentration, quantity and jurisdiction. Verify current requirements through shipping papers, SDS, facility documents and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Phosphorus oxybromide, solid should be stored dry in compatible sealed containers away from water, moisture, oxidizers, acids where incompatible, ignition sources and unauthorized access. Keep compatible dry extinguishing media available.
UN 1939 Quick Details
Common Hazards of UN 1939
- CORROSIVE and TOXIC phosphorus oxybromide solid; dust, vapor or contact may cause severe injury.
- Reacts with water or moist air, releasing heat, hydrogen bromide and phosphoric acid-type fumes.
- Fumes may be heavier than air and collect in low or confined areas.
- Molten material can cause severe burns to skin and eyes.
- Fire may produce irritating, corrosive and/or toxic gases.
- Runoff may spread acidic phosphorus/bromide contamination.
- Containers may rupture or fail when heated or contaminated with water.
Chemical Identity & Physical Properties
White to pale yellow crystalline solid. Pungent, irritating odor. Fumes in moist air.
| Also known as | Phosphoryl bromidePhosphoric tribromide oxidePOBr3Phosphorus tribromide oxide |
| CAS Number | 7789-59-5 |
| Appearance | White to pale yellow crystalline solid. Pungent, irritating odor. Fumes in moist air. |
| Flash Point | Not applicable (non-flammable solid) |
| Boiling Point | 191.7C (377F) |
| Vapor Density | Not applicable (solid, but vapors heavier than air) |
| Water Reactivity | Reacts vigorously with water producing heat, toxic and corrosive hydrogen bromide and phosphoric acid fumes |
Fireground Response Guidance — UN 1939
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for smoke, dust, sulfur dioxide/corrosive vapor or fire exposure. Wear chemical-resistant and fire-appropriate protection selected from SDS; avoid moisture contamination.
Isolation & Evacuation
First Actions for a UN 1939 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, fumes, dust, mist, smoke or gas and avoid skin or eye contact.
- Keep water, foam and moisture away from released product unless incident command confirms a compatible control use.
- Do not touch or walk through spilled 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 leak area and expand the perimeter if vapor, dust, fire involvement, gas accumulation or unknown concentration is present.
- Use ERG Guide 137, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 1939 — Phosphorus oxybromide, solidUse 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.