UN 2188 — Arsine
Placard: Toxic Gas. ERG Guide 119. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2188 is Arsine, an extremely toxic flammable gas assigned to ERG Guide 119. Very low inhalation exposures can be fatal and symptoms may be delayed.
Hazard overview: EXTREMELY TOXIC and FLAMMABLE compressed gas; inhalation may be fatal at very low concentrations. May ignite easily and form explosive mixtures with air. Gas is heavier than air and may collect in low or confined areas.
Response guidance: For a UN 2188 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 2188 should emphasize toxic gas isolation, air monitoring, downwind protection, Level A entry decisions, cylinder control, decontamination and medical coordination. Use ERG 119, SDS and local SOP.
Regulatory context: Arsine 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: Arsine containers should be secured in a cool, ventilated gas storage area away from heat, physical damage and incompatible materials. Toxic, corrosive, oxidizing or refrigerated gases require leak detection/ventilation and emergency planning as specified by SDS and local code.
UN 2188 Quick Details
Common Hazards of UN 2188
- EXTREMELY TOXIC and FLAMMABLE compressed gas; inhalation may be fatal at very low concentrations.
- May ignite easily and form explosive mixtures with air.
- Gas is heavier than air and may collect in low or confined areas.
- Exposure can cause delayed severe blood, kidney and systemic effects.
- Cylinders exposed to fire may vent toxic/flammable gas, rupture or rocket.
- Fire may produce arsenic oxides and other toxic gases.
- Odor is not a reliable warning for exposure.
Chemical Identity & Physical Properties
Colorless gas with a mild garlic-like odor. Shipped as a liquefied compressed gas. Denser than air.
| Also known as | Arsenic trihydrideHydrogen arsenideArseniuretted hydrogenArsenic hydride |
| CAS Number | 7784-42-1 |
| Appearance | Colorless gas with a mild garlic-like odor. Shipped as a liquefied compressed gas. Denser than air. |
| Flash Point | Not applicable (flammable gas) |
| Boiling Point | -62.5C (-80.5F) |
| Vapor Density | 2.7 (heavier than air) |
| Water Reactivity | Slightly soluble in water; hydrolyzes slowly to form arsenic trioxide |
Fireground Response Guidance — UN 2188
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 or refrigerated gas contact is possible.
Isolation & Evacuation
First Actions for a UN 2188 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.
- Treat the release as a serious inhalation hazard and consider downwind protective actions using ERG and incident command.
- Avoid breathing vapors, gas, dust, mist, smoke or fumes and avoid skin or eye contact.
- Eliminate ignition sources if safe and keep vapors and runoff out of drains, sewers, basements and low areas.
- 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, gas accumulation, cylinder heating or unknown product identity.
- Use ERG Guide 119, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 2188 — ArsineUse 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.