UN 2199 — Phosphine
Placard: Toxic Gas. ERG Guide 119. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2199 is Phosphine, an extremely toxic flammable gas assigned to ERG Guide 119. Odor is not reliable and low concentrations can be life-threatening.
Hazard overview: EXTREMELY TOXIC and FLAMMABLE gas; inhalation may be fatal at low concentrations. May ignite and form explosive mixtures with air; some phosphine mixtures can ignite spontaneously. Gas is heavier than air and may collect in low or confined areas.
Response guidance: For a UN 2199 incident, verify the product with shipping papers, container markings, SDS and ERG Guide 119. 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 2199 should emphasize toxic flammable gas behavior, source isolation, downwind monitoring, cylinder cooling, ignition control, Level A decisions and medical coordination. Use ERG 119, SDS and local SOP.
Regulatory context: Phosphine 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: Phosphine containers should be secured in a cool, ventilated gas storage area away from heat, physical damage and incompatible materials. Toxic, flammable, oxidizing, corrosive or refrigerated gases require leak detection/ventilation and emergency planning according to SDS and local code.
UN 2199 Quick Details
Common Hazards of UN 2199
- EXTREMELY TOXIC and FLAMMABLE gas; inhalation may be fatal at low concentrations.
- May ignite and form explosive mixtures with air; some phosphine mixtures can ignite spontaneously.
- Gas is heavier than air and may collect in low or confined areas.
- Odor is not a reliable warning because olfactory fatigue or impurities may mislead responders.
- Contact with liquefied gas may cause frostbite.
- Cylinders exposed to fire may vent toxic/flammable gas, rupture or rocket.
- Fire may produce phosphorus oxides and toxic/corrosive gases.
Chemical Identity & Physical Properties
Colorless gas with a fish-like or garlic-like odor. Highly toxic and flammable. May appear as a compressed liquefied gas.
| Also known as | Hydrogen phosphidePhosphorus trihydridePH3Phosphorated hydrogen |
| CAS Number | 7803-51-2 |
| Appearance | Colorless gas with a fish-like or garlic-like odor. Highly toxic and flammable. May appear as a compressed liquefied gas. |
| Flash Point | Not applicable (flammable gas, ignites spontaneously in air above 100°F/38°C) |
| Boiling Point | -88°C (-126°F) |
| Vapor Density | 1.2 (heavier than air) |
| Water Reactivity | Slight hydrolysis in water; phosphine itself has limited water reactivity but may form flammable hydrogen gas |
Fireground Response Guidance — UN 2199
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA and fully encapsulating chemical protective clothing for close entry or unknown concentrations. Level A may be needed; protect against frostbite where liquefied gas contact is possible.
Isolation & Evacuation
First Actions for a UN 2199 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 gas, vapor, dust, mist, smoke or fumes and avoid skin or eye contact.
- Eliminate ignition sources if safe and treat the release as both toxic and flammable.
- 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/gas spread, cylinder heating, oxidizer reaction or unknown product identity.
- Use ERG Guide 119, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 2199 — PhosphineUse 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.