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 At a Glance
UN 3522 (Arsine, adsorbed) is listed as DOT Class 2 Toxic Gas and is assigned to ERG Guide 173. Use this page to review placard data, common hazards, PPE notes, isolation context, first actions, and related UN numbers.
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.