☣️ UN 3307 • CLASS 2
UN 3307 — Liquefied gas, poisonous, oxidizing, n.o.s. (Inhalation Hazard Zone A)
Placard: Toxic Gas. ERG Guide 124. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
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⚠️ Verification required:
Broad or variable material category; verify exact product, SDS and shipping papers.
⚠️ 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.
Liquefied gas, poisonous, oxidizing, n.o.s. (Inhalation Hazard Zone A) is a Zone A toxic gas entry with severe inhalation hazard. Releases require immediate isolation, air monitoring and specialized hazmat control.
Hazard overview: Toxic oxidizing liquefied gas may be fatal if inhaled and may also be corrosive, oxidizing or flammable depending on the exact gas. Vapors can spread along the ground and threaten downwind areas.
Response guidance: Use ERG Guide 124 and Table 1 distances, stay upwind, deny entry and evacuate downwind as directed. Do not attempt leak control without Level A protection and gas-specific monitoring.
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UN 3307 Quick Details
UN 3307
Product name: Liquefied gas, poisonous, oxidizing, n.o.s. (Inhalation Hazard Zone A)
DOT Class: 2
Placard type: Toxic Gas
ERG Guide: 124 (check current ERG)
Initial 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
Common Hazards of UN 3307
- 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.).
Chemical Identity & Physical Properties
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.
| 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 |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 3307
Extinguishing Media
Do not use water directly on leak; use water spray from distance to cool containers; dry chemical or CO2 for small fires
PPE Requirements
⚠️ Level A required; SCBA with full facepiece; gas-tight chemical protective suit; extreme inhalation hazard Zone A requires maximum respiratory protection
Level A required; SCBA with full facepiece; gas-tight chemical protective suit; extreme inhalation hazard Zone A requires maximum respiratory protection.
Isolation & Evacuation
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
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 124).
First Actions for a UN 3307 Incident
- CALL 911, then contact the emergency response telephone number shown on shipping papers, if available.
- 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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📋 Copy & Share Field Card
UN 3307 — Liquefied gas, poisonous, oxidizing, n.oHAZMAT 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 contact the emergency response telephone number shown on shipping papers, if available.
• 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/liquefied-gas-poisonous-oxidizing-un-3307 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
UN3307 Liquefied gas, poisonous, oxidizing, n.o.s. (Inhalation Hazard Zone A) Cls2 ERG124 | allfirefighter.com/hazmat/un/liquefied-gas-poisonous-oxidizing-un-3307SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions.
Page: https://allfirefighter.com/hazmat/un/liquefied-gas-poisonous-oxidizing-un-3307
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Frequently Asked Questions about UN 3307
UN 3307 is Liquefied gas, poisonous, oxidizing, n.o.s. (Inhalation Hazard Zone A), assigned to ERG Guide 124 and placarded as Toxic Gas.
Yes. Toxic oxidizing liquefied gas presents a serious toxic exposure hazard; avoid inhalation, ingestion, skin contact and contaminated runoff.
Yes, corrosive effects are possible. Avoid skin and eye contact and use chemical-resistant protection.
Gas can spread downwind, collect in low or confined areas, displace oxygen or create toxic exposure depending on the material.
Use caution. May react with water depending on specific gas composition; some oxidizers react violently
Do not use water directly on leak; use water spray from distance to cool containers; dry chemical or CO2 for small fires.
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.