UN 1833 — Sulphurous acid
Placard: Corrosive. ERG Guide 154. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1833 is Sulphurous acid, a corrosive sulfur dioxide solution assigned to ERG Guide 154. It can release irritating sulfur dioxide gas and acidic runoff.
Hazard overview: UN 1833 presents corrosive liquid, sulfur dioxide vapor, respiratory irritation and acidic-runoff hazards. Vapors may collect in low or poorly ventilated areas.
Response guidance: For a UN 1833 incident, responders should verify the product with shipping papers, package markings, SDS and ERG Guide 154. Establish incident command, isolate the area, stay upwind, prevent incompatible contact, control runoff and choose entry or fire-control actions based on monitoring, SDS and local SOP.
Firefighter training notes: Training for UN 1833 should emphasize corrosive/toxic exposure routes, water incompatibility where applicable, air monitoring, PPE selection, decontamination and runoff containment. Use ERG 154, SDS and local SOP.
Regulatory context: Sulphurous acid is regulated as a hazardous material for transportation and emergency response purposes. Transportation, workplace exposure, spill reporting, waste handling, storage and environmental requirements may vary by concentration, formulation, quantity and jurisdiction. Verify current requirements through shipping papers, SDS, facility documents and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Sulphurous acid should be stored in tightly closed compatible containers in a secure, cool, dry, well-ventilated hazardous-material area according to SDS and local procedures.
UN 1833 Quick Details
Common Hazards of UN 1833
- CORROSIVE sulfur dioxide solution; inhalation, ingestion or skin/eye contact may cause injury.
- Can release sulfur dioxide gas, especially if heated, agitated or acid/base conditions change.
- Sulfur dioxide vapor is irritating and may collect in low or poorly ventilated areas.
- Non-flammable aqueous solution, but fire may produce sulfur oxides.
- Runoff may be acidic and harmful to waterways.
- Containers may rupture or fail when heated.
- Avoid breathing vapor or mist.
Chemical Identity & Physical Properties
Colorless to pale yellow aqueous solution with a sharp, pungent sulfur dioxide odor. Exists only in solution, decomposes to release SO2 gas.
| Also known as | Sulfurous acidSulfur dioxide solutionSO2 in waterBisulfite solution |
| CAS Number | 7782-99-2 |
| Appearance | Colorless to pale yellow aqueous solution with a sharp, pungent sulfur dioxide odor. Exists only in solution, decomposes to release SO2 gas. |
| Flash Point | Not applicable (non-flammable aqueous solution) |
| Boiling Point | Approximately 100C (212F) with decomposition releasing SO2 |
| Vapor Density | Not applicable (aqueous solution) |
| Water Reactivity | Miscible with water; already an aqueous solution of sulfur dioxide |
Fireground Response Guidance — UN 1833
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for dust, vapor, mist, fire or confined-space exposure. Wear chemical-resistant gloves, boots, eye/face protection and protective clothing selected from SDS for corrosive contact.
Isolation & Evacuation
First Actions for a UN 1833 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.
- Avoid breathing vapors, fumes, dust, mist or spray and avoid skin or eye contact.
- Do not touch or walk through spilled material unless properly trained and wearing appropriate protective equipment.
- Ventilate closed spaces before entering, but only if properly trained, equipped, monitored and authorized by incident command.
- Isolate the spill or leak area and expand the perimeter if vapor, dust, fire involvement, water reaction or unknown concentration is present.
- Use ERG Guide 154, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 1833 — Sulphurous acidUse 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.