☣️ UN 3355 • CLASS 2
UN 3355 — Insecticide gas, poisonous, flammable, n.o.s. (Inhalation Hazard Zone A)
Placard: Toxic Gas. ERG Guide 119. 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.
UN 3355 is a toxic gas inhalation hazard entry for flammable insecticide or fumigant gases. Zone A means maximum inhalation danger and requires conservative protective actions.
Hazard overview: This gas may be fatal if inhaled or absorbed through skin. It is also flammable, may form explosive mixtures with air and can spread along the ground.
Response guidance: Apply ERG 119 protective distances, evacuate downwind areas, eliminate ignition sources and stop the leak only by trained personnel using remote methods when safe.
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UN 3355 Quick Details
UN 3355
Product name: Insecticide gas, poisonous, flammable, n.o.s. (Inhalation Hazard Zone A)
DOT Class: 2
Placard type: Toxic Gas
ERG Guide: 119 (check current ERG)
Initial isolation: ERG 119: Isolate 800m (0.5 mi) all directions initially. Evacuate downwind 8+ km if large spill. Inhalation Hazard Zone A requires maximum protective actions
Common Hazards of UN 3355
- TOXIC; may be fatal if inhaled or absorbed through skin. Some may cause severe skin burns and eye damage.
- 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.
- Flammable; may be ignited by heat, sparks or flames.
- May form explosive mixtures with air; some materials may react explosively even without air.
- Those substances designated with a (P) may polymerize explosively when heated or involved in a fire.
- Vapors from liquefied gas are initially heavier than air and spread along ground.
Chemical Identity & Physical Properties
Compressed or liquefied gas, typically colorless to pale yellow. May have characteristic odor depending on specific insecticide formulation. Highly toxic by inhalation.
| Also known as | Poisonous insecticide gasToxic fumigant gasFlammable pest control gasHazardous insecticide vapor |
| Appearance | Compressed or liquefied gas, typically colorless to pale yellow. May have characteristic odor depending on specific insecticide formulation. Highly toxic by inhalation. |
| Flash Point | Not applicable (flammable gas) |
| Boiling Point | Not applicable (compressed gas, varies by formulation) |
| Vapor Density | Heavier than air (exact value depends on specific insecticide) |
| Water Reactivity | No significant reaction with water, though solubility varies by formulation |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 3355
Extinguishing Media
Do not use water spray. Use dry chemical or CO2 if gas flow can be stopped safely
PPE Requirements
⚠️ Level A required; SCBA with full encapsulating suit mandatory. Extreme inhalation hazard Zone A; skin absorption risk
Level A with fully encapsulating suit and SCBA is required for release response; avoid all skin and vapor exposure.
Isolation & Evacuation
ERG 119: Isolate 800m (0.5 mi) all directions initially. Evacuate downwind 8+ km if large spill. Inhalation Hazard Zone A requires maximum protective actions
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 119).
First Actions for a UN 3355 Incident
- CALL 911. Then call the emergency response telephone number on the shipping paper, if available.
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Many gases are heavier than air and may 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 downwind precautions when vapor, dust, or runoff hazards are present.
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📋 Copy & Share Field Card
UN 3355 — Insecticide gas, poisonous, flammable, nHAZMAT RADIO NOTE — UN 3355
Product: Insecticide gas, poisonous, flammable, n.o.s. (Inhalation Hazard Zone A)
Class 2 / Toxic Gas / ERG 119
PPE: Level A required; SCBA with full encapsulating suit mandatory. Extreme inhalation hazard Zone A; skin absorption risk
ISOLATION: ERG 119: Isolate 800m (0.5 mi) all directions initially. Evacuate downwind 8+ km if large spill. Inhalation Hazard Zone A requires maximum protective actions
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 3355 — Insecticide gas, poisonous, flammable, n.o.s. (Inhalation Hazard Zone A)
Class: 2 | Placard: Toxic Gas | ERG Guide: 119
Appearance: Compressed or liquefied gas, typically colorless to pale yellow. May have characteristic odor depending on specific insecticide formulation. Highly toxic by inhalation.
Water Reactivity: No significant reaction with water, though solubility varies by formulation
Extinguishing: Do not use water spray. Use dry chemical or CO2 if gas flow can be stopped safely
PPE: Level A required; SCBA with full encapsulating suit mandatory. Extreme inhalation hazard Zone A; skin absorption risk
Isolation: ERG 119: Isolate 800m (0.5 mi) all directions initially. Evacuate downwind 8+ km if large spill. Inhalation Hazard Zone A requires maximum protective actions
— Key Hazards —
• TOXIC; may be fatal if inhaled or absorbed through skin. Some may cause severe skin burns and eye damage.
• Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite.
• Fire will produce irritating, corrosive and/or toxic gases.
— First Actions —
• CALL 911. Then call the emergency response telephone number on the shipping paper, if available.
• Keep unauthorized personnel away.
• Stay upwind, uphill and/or upstream.
• Many gases are heavier than air and may collect in low or confined areas.
SOURCE: allfirefighter.com/hazmat/un/insecticide-gas-poisonous-flammable-un-3355 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
UN3355 Insecticide gas, poisonous, flammable, n.o.s. (Inhalation Hazard Zone A) Cls2 ERG119 | allfirefighter.com/hazmat/un/insecticide-gas-poisonous-flammable-un-3355SMS / 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/insecticide-gas-poisonous-flammable-un-3355
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Frequently Asked Questions about UN 3355
Zone A indicates an extreme inhalation hazard requiring the most protective initial actions.
Yes. It is a poisonous flammable gas and can flash back to an ignition source.
No. SCBA and fully encapsulating chemical protection are required for response.
Isolate the area, evacuate downwind, stay upwind and notify hazmat specialists.
Do not use water spray directly on the leak; use only methods approved by incident command and product data.
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.