UN 3522 — Arsine, adsorbed
Placard: Toxic Gas. ERG Guide 173. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 3522 is Arsine, adsorbed, an extremely toxic adsorbed arsine gas assigned to ERG Guide 173. Delayed systemic toxicity and flammability require specialist control.
Hazard overview: EXTREMELY TOXIC arsine gas adsorbed on a porous solid; inhalation may be fatal. Arsine may cause delayed severe systemic effects, including hemolysis; odor is not a safe warning. Gas is flammable and may ignite or form explosive mixtures in air.
Response guidance: For UN 3522, isolate downwind/low areas, treat as a life-threatening gas release and use Level A/SCBA for entry. Verify exact gas with shipping papers and ERG 173.
Firefighter training notes: Training for UN 3522 should emphasize toxic-gas recognition, Zone A isolation, Level A/SCBA entry, air monitoring, source-control limits and decontamination. Use ERG 173, SDS and local SOP.
Regulatory context: Arsine, adsorbed is regulated as a hazardous material for transport and emergency response. Storage, reporting, exposure, waste and incident-notification duties depend on quantity, package type, gas identity and jurisdiction; verify shipping papers, SDS and authority guidance.
Storage & handling: Arsine, adsorbed should be stored in secured compatible adsorbed-gas packages away from heat, impact, corrosion, moisture where incompatible and unauthorized access, with ventilation and emergency planning.
UN 3522 Quick Details
Common Hazards of UN 3522
- EXTREMELY TOXIC arsine gas adsorbed on a porous solid; inhalation may be fatal.
- Arsine may cause delayed severe systemic effects, including hemolysis; odor is not a safe warning.
- Gas is flammable and may ignite or form explosive mixtures in air.
- Released gas is heavier than air and can collect in low or confined areas.
- Fire may produce arsenic oxides and toxic smoke.
- Cylinder/package heating can release gas or rupture containers.
- Runoff and debris may carry arsenic contamination.
Chemical Identity & Physical Properties
Colorless to pale yellow gas with a mild garlic-like odor. Shipped adsorbed on an inert porous material in cylinders. Extremely toxic and pyrophoric in air.
| Also known as | Arsenic trihydrideHydrogen arsenideArseniuretted hydrogenArsenic hydride |
| CAS Number | 7784-42-1 |
| Appearance | Colorless to pale yellow gas with a mild garlic-like odor. Shipped adsorbed on an inert porous material in cylinders. Extremely toxic and pyrophoric in air. |
| Flash Point | Not applicable (gas) |
| Boiling Point | -62C (-80F) |
| Vapor Density | 2.7 (heavier than air) |
| Water Reactivity | Decomposes slowly in water, no violent reaction |
Fireground Response Guidance — UN 3522
Extinguishing Media
PPE Requirements
Use Level A fully encapsulating chemical protective clothing with positive-pressure SCBA for entry. Zone A toxic gas requires maximum respiratory and skin protection.
Isolation & Evacuation
First Actions for a UN 3522 Incident
- Call 911 and the emergency response number on the shipping paper, if available.
- Keep unauthorized personnel away and establish incident command.
- Stay upwind and avoid low or poorly ventilated areas unless monitoring shows they are safe.
- Treat the release as a life-threatening inhalation hazard until the gas is identified and monitored.
- Eliminate ignition sources if this can be done safely.
- Do not handle leaking cylinders, adsorbed-gas packages or damaged gas articles without proper training and PPE.
- Ventilate only after monitoring and only if properly trained and equipped.
- Use ERG Guide 173, shipping papers, markings and air monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 3522 — Arsine, adsorbedUse 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.