UN 1040 — Ethylene oxide
Placard: Flammable Gas. ERG Guide 119P. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1040 is Ethylene oxide, an extremely flammable toxic gas assigned to ERG Guide 119P. Polymerization, flashback and inhalation exposure drive response.
Hazard overview: EXTREMELY FLAMMABLE and TOXIC gas; vapors can form explosive mixtures with air. May polymerize violently if heated, contaminated or uninhibited. Vapors are heavier than air and may travel to ignition sources and flash back.
Response guidance: For UN 1040, isolate low areas, eliminate ignition sources and cool containers from protection. Do not extinguish leak flames unless flow can be stopped safely.
Firefighter training notes: Training for UN 1040 should emphasize flammable vapor control, polymerization warning signs, container cooling, SCBA use, decontamination and runoff control. Use ERG 119P, SDS and local SOP.
Regulatory context: Ethylene oxide is regulated as a hazardous material for transport and emergency response. Storage, reporting, exposure, waste and incident-notification duties depend on quantity, concentration, package type and jurisdiction; verify shipping papers, SDS and authority guidance.
Storage & handling: Ethylene oxide should be stored in approved pressure containers away from heat, ignition sources and contamination, with ventilation, grounding/bonding and polymerization/stabilizer controls.
UN 1040 Quick Details
Common Hazards of UN 1040
- EXTREMELY FLAMMABLE and TOXIC gas; vapors can form explosive mixtures with air.
- May polymerize violently if heated, contaminated or uninhibited.
- Vapors are heavier than air and may travel to ignition sources and flash back.
- Inhalation exposure can cause serious acute injury; chronic exposure is a cancer concern.
- Cylinders or containers exposed to fire may vent, rupture or explode.
- Fire may produce carbon monoxide, irritating smoke and toxic decomposition products.
- Runoff and decontamination water may carry contaminated residues.
Chemical Identity & Physical Properties
Ethylene oxide physical appearance should be verified from SDS, package labels and shipping papers.
| Also known as | EOEpoxyethaneOxirane |
| CAS Number | 75-21-8 |
| Flash Point | -18°C (0°F) |
| Boiling Point | 10.7°C (51°F) |
| Vapor Density | 1.5 |
Fireground Response Guidance — UN 1040
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA and chemical protective clothing; Level A may be needed for unknown concentration, heavy vapor, splash or skin-absorption risk.
Isolation & Evacuation
First Actions for a UN 1040 Incident
- Call 911 and the emergency response number on the shipping paper, if available.
- Keep unauthorized personnel away and establish incident command.
- Stay upwind, uphill and upstream.
- Eliminate ignition sources if this can be done safely.
- Watch for polymerization, container heating or pressure buildup.
- Avoid breathing vapor, gas, mist, smoke or fumes and avoid skin or eye contact.
- Do not touch damaged containers or spilled material without proper training and PPE.
- Prevent contaminated liquid, runoff and decontamination waste from spreading.
- Ventilate confined spaces only after monitoring and only if properly trained and equipped.
- Use ERG Guide 119P, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 1040 — Ethylene oxideUse for: Quick radio or face-to-face size-up. Short, structured, field-ready.
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
Use for: Quick text to command or incoming units. Fits in a single SMS.