☣️ UN 3539 • CLASS 2
Articles containing toxic gas, n.o.s.
Placard: Toxic Gas. 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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Quick details
UN 3539
Class: 2
Placard type: Toxic Gas
ERG: Guide 123 (check current ERG)
Isolation: ERG 123: isolate 100m all directions initially; for large spill isolate 800m downwind during day, 1600m at night
Chemical & Response Details
| Also known as | Toxic gas articles NOSArticles with toxic gasPackaged toxic gas itemsDevices containing toxic gas |
| Appearance | Various articles, devices, or equipment containing compressed or liquefied toxic gases. Physical form depends on the specific article, but contains gas under pressure that may be colorless or colored, with odor varying by gas type. |
| Flash Point | Not applicable (varies by contained gas) |
| Boiling Point | Not applicable (varies by contained gas) |
| Vapor Density | Varies by contained gas (potentially heavier than air) |
| Water Reactivity | Varies depending on specific toxic gas contained; some may react violently with water |
| Extinguishing | Do not use water; handle as per specific toxic gas; ventilate area |
| PPE | ⚠️ Level A recommended; SCBA required; full chemical protective suit; avoid all contact with material |
| Isolation | ERG 123: isolate 100m all directions initially; for large spill isolate 800m downwind during day, 1600m at night |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Common hazards (high level)
- TOXIC; may be fatal if inhaled or absorbed through skin.
- Vapors may be irritating and/or corrosive.
- Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite.
- Fire will produce irritating, corrosive and/or toxic gases.
- Runoff from fire control or dilution water may cause environmental contamination.
- Some may burn but none ignite readily.
- Vapors from liquefied gas are initially heavier than air and spread along ground.
- Cylinders exposed to fire may vent and release toxic and/or corrosive gas through pressure relief
First actions (field-minded)
- 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.
- For highlighted materials: see Table 1 - Initial Isolation and Protective Action Distances.
- For non-highlighted materials: increase the immediate precautionary measure distance, in the downwind
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UN 3539 — Articles containing toxic gas, n.o.s. HAZMAT RADIO NOTE — UN 3539
Product: Articles containing toxic gas, n.o.s.
Class 2 / Toxic Gas / ERG 123
PPE: Level A recommended; SCBA required; full chemical protective suit; avoid all contact with material
ISOLATION: ERG 123: isolate 100m all directions initially; for large spill isolate 800m downwind during day, 1600m at night
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 3539 — Articles containing toxic gas, n.o.s.
Class: 2 | Placard: Toxic Gas | ERG Guide: 123
Appearance: Various articles, devices, or equipment containing compressed or liquefied toxic gases. Physical form depends on the specific article, but contains gas under pressure that may be colorless or colored, with odor varying by gas type.
Water Reactivity: Varies depending on specific toxic gas contained; some may react violently with water
Extinguishing: Do not use water; handle as per specific toxic gas; ventilate area
PPE: Level A recommended; SCBA required; full chemical protective suit; avoid all contact with material
Isolation: ERG 123: isolate 100m all directions initially; for large spill isolate 800m downwind during day, 1600m at night
— Key Hazards —
• TOXIC; may be fatal if inhaled or absorbed through skin.
• Vapors may be irritating and/or corrosive.
• Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite.
— 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/3539 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3539 Articles containing toxic gas, n.o.s. Cls2 ERG123 | allfirefighter.com/hazmat/un/3539SMS / 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/3539
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FAQ
TOXIC; may be fatal if inhaled or absorbed through skin. Vapors may be irritating and/or corrosive. Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite. Fire will produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may cause environmental contamination. Some may burn but none ignite readily. Vapors from liquefied gas are initially heavier than air and spread along ground. Cylinders exposed to fire may vent and release toxic and/or corrosive gas through pressure relief
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 recommended; SCBA required; full chemical protective suit; avoid all contact with material
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 123 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.