☣️ UN 3307 • CLASS 2
Liquefied gas, poisonous, oxidizing, n.o.s. (Inhalation Hazard Zone A)
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 3307
Class: 2
Placard type: Toxic Gas
ERG: Guide 124 (check current ERG)
Isolation: ERG 124: isolate 800m (1/2 mile) all directions initially; for large spills isolate 1600m (1 mile) downwind; evacuate immediate area and consider evacuation up to 11km (7 miles) downwind if large release occurs
Chemical & Response Details
| Also known as | Liquefied poisonous oxidizing gas n.o.s.Toxic oxidizing compressed gasPoisonous liquefied oxidizing gasInhalation Hazard Zone A oxidizing gas |
| Appearance | Liquefied compressed gas under pressure; physical state and color varies by specific composition. May be colorless or have characteristic color depending on specific oxidizing gas. Odor varies; some may be odorless making detection difficult. |
| Flash Point | Not applicable (oxidizing gas supports combustion) |
| Boiling Point | Varies by specific gas composition; typically below room temperature when at atmospheric pressure |
| Vapor Density | Heavier than air (gas will accumulate in low-lying areas and confined spaces) |
| Water Reactivity | May react with water depending on specific gas composition; some oxidizers react violently |
| Extinguishing | Do not use water directly on leak; use water spray from distance to cool containers; dry chemical or CO2 for small fires |
| PPE | ⚠️ Level A required; SCBA with full facepiece; gas-tight chemical protective suit; extreme inhalation hazard Zone A requires maximum respiratory protection |
| Isolation | ERG 124: isolate 800m (1/2 mile) all directions initially; for large spills isolate 1600m (1 mile) downwind; evacuate immediate area and consider evacuation up to 11km (7 miles) downwind if large release occurs |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Common hazards (high level)
- TOXIC and/or CORROSIVE; may be fatal if inhaled or absorbed through skin.
- Fire will produce irritating, corrosive and/or toxic gases.
- Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite.
- Runoff from fire control or dilution water may cause environmental contamination.
- Substance does not burn but will support combustion.
- Vapors from liquefied gas are initially heavier than air and spread along ground.
- These are strong oxidizers and will react vigorously or explosively with many materials including fuels.
- May ignite combustibles (wood, paper, oil, clothing, etc.).
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.
- See Table 1 - Initial Isolation and Protective Action Distances.
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UN 3307 — Liquefied gas, poisonous, oxidizing, n.o HAZMAT RADIO NOTE — UN 3307
Product: Liquefied gas, poisonous, oxidizing, n.o.s. (Inhalation Hazard Zone A)
Class 2 / Toxic Gas / ERG 124
PPE: Level A required; SCBA with full facepiece; gas-tight chemical protective suit; extreme inhalation hazard Zone A requires maximum respiratory protection
ISOLATION: ERG 124: isolate 800m (1/2 mile) all directions initially; for large spills isolate 1600m (1 mile) downwind; evacuate immediate area and consider evacuation up to 11km (7 miles) downwind if large release occurs
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 3307 — Liquefied gas, poisonous, oxidizing, n.o.s. (Inhalation Hazard Zone A)
Class: 2 | Placard: Toxic Gas | ERG Guide: 124
Appearance: Liquefied compressed gas under pressure; physical state and color varies by specific composition. May be colorless or have characteristic color depending on specific oxidizing gas. Odor varies; some may be odorless making detection difficult.
Water Reactivity: May react with water depending on specific gas composition; some oxidizers react violently
Extinguishing: Do not use water directly on leak; use water spray from distance to cool containers; dry chemical or CO2 for small fires
PPE: Level A required; SCBA with full facepiece; gas-tight chemical protective suit; extreme inhalation hazard Zone A requires maximum respiratory protection
Isolation: ERG 124: isolate 800m (1/2 mile) all directions initially; for large spills isolate 1600m (1 mile) downwind; evacuate immediate area and consider evacuation up to 11km (7 miles) downwind if large release occurs
— Key Hazards —
• TOXIC and/or CORROSIVE; may be fatal if inhaled or absorbed through skin.
• Fire will produce irritating, corrosive and/or toxic gases.
• 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/3307 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3307 Liquefied gas, poisonous, oxidizing, n.o.s. (Inhalation Hazard Zone A) Cls2 ERG124 | allfirefighter.com/hazmat/un/3307SMS / 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/3307
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FAQ
TOXIC and/or CORROSIVE; may be fatal if inhaled or absorbed through skin. Fire will produce irritating, corrosive and/or toxic gases. Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite. Runoff from fire control or dilution water may cause environmental contamination. Substance does not burn but will support combustion. Vapors from liquefied gas are initially heavier than air and spread along ground. These are strong oxidizers and will react vigorously or explosively with many materials including fuels. May ignite combustibles (wood, paper, oil, clothing, etc.).
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; SCBA with full facepiece; gas-tight chemical protective suit; extreme inhalation hazard Zone A requires maximum respiratory protection
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 124 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.