☣️ UN 3522 • CLASS 2
UN 3522 — Arsine, adsorbed
Placard: Toxic Gas. ERG Guide 173. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
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⚠️ This page is a quick-reference aid. For real incidents: stage upwind, isolate, deny entry, request Hazmat early, and consult the current ERG + SOP/SOG.
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UN 3522 Quick Details
UN 3522
Product name: Arsine, adsorbed
DOT Class: 2
Placard type: Toxic Gas
ERG Guide: 173 (check current ERG)
Initial isolation: ERG 173: isolate 100m in all directions; evacuate 800m downwind if release; 1600m if tank/rail car involved in fire
Common Hazards of UN 3522
- TOXIC; may be fatal if inhaled or absorbed through skin.
- Vapors may be irritating.
- Contact with gas may cause burns and injury.
- Fire will produce irritating, corrosive and/or toxic gases.
- Runoff from fire control or dilution water may cause environmental contamination.
- Some gases may burn or be ignited by heat, sparks or flames.
- May form explosive mixtures with air.
- Oxidizers may ignite combustibles (wood, paper, oil, clothing, etc.) but NOT readily due to low
Chemical Identity & Physical Properties
| 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 |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 3522
Extinguishing Media
Do not use water or foam; use dry chemical or CO2 only
PPE Requirements
⚠️ Level A required; full encapsulation with SCBA; chemical-resistant gloves and suits; extreme toxicity hazard
Isolation & Evacuation
ERG 173: isolate 100m in all directions; evacuate 800m downwind if release; 1600m if tank/rail car involved in fire
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 173).
First Actions for a UN 3522 Incident
- CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Many gases are heavier than air and will spread along the ground and collect in low or confined areas
- Ventilate closed spaces before entering, but only if properly trained and equipped.
- Isolate spill or leak area for at least 100 meters (330 feet) in all directions.
- See Table 1 - Initial Isolation and Protective Action Distances.
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UN 3522 — Arsine, adsorbedHAZMAT RADIO NOTE — UN 3522
Product: Arsine, adsorbed
Class 2 / Toxic Gas / ERG 173
PPE: Level A required; full encapsulation with SCBA; chemical-resistant gloves and suits; extreme toxicity hazard
ISOLATION: ERG 173: isolate 100m in all directions; evacuate 800m downwind if release; 1600m if tank/rail car involved in fire
ACTION: Stage upwind · Isolate · Deny entry · Request HazmatRADIO
Use for: Quick radio or face-to-face size-up. Short, structured, field-ready.
=== IC HAZMAT BRIEFING ===
UN 3522 — Arsine, adsorbed
Class: 2 | Placard: Toxic Gas | ERG Guide: 173
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.
Water Reactivity: Decomposes slowly in water, no violent reaction
Extinguishing: Do not use water or foam; use dry chemical or CO2 only
PPE: Level A required; full encapsulation with SCBA; chemical-resistant gloves and suits; extreme toxicity hazard
Isolation: ERG 173: isolate 100m in all directions; evacuate 800m downwind if release; 1600m if tank/rail car involved in fire
— Key Hazards —
• TOXIC; may be fatal if inhaled or absorbed through skin.
• Vapors may be irritating.
• Contact with gas may cause burns and injury.
— First Actions —
• CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
• Keep unauthorized personnel away.
• Stay upwind, uphill and/or upstream.
• Many gases are heavier than air and will spread along the ground and collect in low or confined areas
SOURCE: allfirefighter.com/hazmat/un/3522 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3522 Arsine, adsorbed Cls2 ERG173 | ERG 173: isolate 100m in all directions; evacuate 800m downwind if release; 1600 | allfirefighter.com/hazmat/un/3522SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS. Includes link to full page.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions.
Page: https://allfirefighter.com/hazmat/un/3522
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Frequently Asked Questions about UN 3522
TOXIC; may be fatal if inhaled or absorbed through skin. Vapors may be irritating. Contact with gas may cause burns and injury. Fire will produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may cause environmental contamination. Some gases may burn or be ignited by heat, sparks or flames. May form explosive mixtures with air. Oxidizers may ignite combustibles (wood, paper, oil, clothing, etc.) but NOT readily due to low
CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper Keep unauthorized personnel away. Stay upwind, uphill and/or upstream.
Level A required; full encapsulation with SCBA; chemical-resistant gloves and suits; extreme toxicity hazard
Water reactivity: Decomposes slowly in water, no violent reaction. Recommended extinguishing: Do not use water or foam; use dry chemical or CO2 only.
ERG Guide 173 recommendation: ERG 173: isolate 100m in all directions; evacuate 800m downwind if release; 1600m if tank/rail car involved in fire
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 173 and your department SOP/SOG for incident-specific protective actions.
Sources (high level): DOT/PHMSA marking & class concepts + ERG usage principles.
This page does not reproduce ERG guide text—always consult the current ERG for incident-specific protective actions.