☣️ UN 3498 • CLASS 8
UN 3498 — Iodine monochloride, liquid
Placard: Corrosive. ERG Guide 157. 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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UN 3498 Quick Details
UN 3498
Product name: Iodine monochloride, liquid
DOT Class: 8
Placard type: Corrosive
ERG Guide: 157 (check current ERG)
Initial isolation: ERG 157: isolate spill or leak area immediately for at least 50-100 meters in all directions; evacuate downwind areas if material is releasing vapors or fumes
Common Hazards of UN 3498
- TOXIC and/or CORROSIVE; inhalation, ingestion or contact (skin, eyes) with vapors, dusts or substance
- Reaction with water or moist air may release toxic, corrosive or flammable gases.
- Reaction with water may generate much heat that will increase the concentration of fumes in the air.
- Fire will produce irritating, corrosive and/or toxic gases.
- Runoff from fire control or dilution water may be corrosive and/or toxic and cause environmental
- Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive
- UN1802, UN2032, UN3084, UN3093, UN1796 (above 50%), UN1826 (above 50%), and UN2031 (above
- Vapors may accumulate in confined areas (basement, tanks, hopper/tank cars, etc.).
Chemical Identity & Physical Properties
| Also known as | IClIodine chlorideWijs chlorideChloroiodine |
| CAS Number | 7790-99-0 |
| Appearance | Reddish-brown to dark brown oily liquid with a pungent, acrid odor. Fumes in moist air due to reaction with water vapor. |
| Flash Point | Not applicable (non-flammable liquid) |
| Boiling Point | 97C (207F) with decomposition |
| Vapor Density | 6.5 (much heavier than air) |
| Water Reactivity | Reacts violently with water producing toxic and corrosive fumes of hydrogen chloride and iodine vapor; generates significant heat |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 3498
Extinguishing Media
Dry chemical, dry sand, or carbon dioxide only; do not use water or foam
PPE Requirements
⚠️ Level A required for spill response; SCBA and full chemical-resistant suit mandatory; double gloves recommended due to severe corrosive properties
Isolation & Evacuation
ERG 157: isolate spill or leak area immediately for at least 50-100 meters in all directions; evacuate downwind areas if material is releasing vapors or fumes
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 157).
First Actions for a UN 3498 Incident
- CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Ventilate closed spaces before entering, but only if properly trained and equipped.
- Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters
- For highlighted materials: see Table 1 - Initial Isolation and Protective Action Distances.
- For non-highlighted materials: increase the immediate precautionary measure distance, in the downwind
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📋 Copy & Share Field Card
UN 3498 — Iodine monochloride, liquidHAZMAT RADIO NOTE — UN 3498
Product: Iodine monochloride, liquid
Class 8 / Corrosive / ERG 157
PPE: Level A required for spill response; SCBA and full chemical-resistant suit mandatory; double gloves recommended due to severe corrosive properties
ISOLATION: ERG 157: isolate spill or leak area immediately for at least 50-100 meters in all directions; evacuate downwind areas if material is releasing vapors or fumes
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 3498 — Iodine monochloride, liquid
Class: 8 | Placard: Corrosive | ERG Guide: 157
Appearance: Reddish-brown to dark brown oily liquid with a pungent, acrid odor. Fumes in moist air due to reaction with water vapor.
Water Reactivity: Reacts violently with water producing toxic and corrosive fumes of hydrogen chloride and iodine vapor; generates significant heat
Extinguishing: Dry chemical, dry sand, or carbon dioxide only; do not use water or foam
PPE: Level A required for spill response; SCBA and full chemical-resistant suit mandatory; double gloves recommended due to severe corrosive properties
Isolation: ERG 157: isolate spill or leak area immediately for at least 50-100 meters in all directions; evacuate downwind areas if material is releasing vapors or fumes
— Key Hazards —
• TOXIC and/or CORROSIVE; inhalation, ingestion or contact (skin, eyes) with vapors, dusts or substance
• Reaction with water or moist air may release toxic, corrosive or flammable gases.
• Reaction with water may generate much heat that will increase the concentration of fumes in the air.
— 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.
• Ventilate closed spaces before entering, but only if properly trained and equipped.
SOURCE: allfirefighter.com/hazmat/un/3498 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3498 Iodine monochloride, liquid Cls8 ERG157 | allfirefighter.com/hazmat/un/3498SMS / 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/3498
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Frequently Asked Questions about UN 3498
TOXIC and/or CORROSIVE; inhalation, ingestion or contact (skin, eyes) with vapors, dusts or substance Reaction with water or moist air may release toxic, corrosive or flammable gases. Reaction with water may generate much heat that will increase the concentration of fumes in the air. Fire will produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause environmental Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive UN1802, UN2032, UN3084, UN3093, UN1796 (above 50%), UN1826 (above 50%), and UN2031 (above Vapors may accumulate in confined areas (basement, tanks, hopper/tank cars, 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 for spill response; SCBA and full chemical-resistant suit mandatory; double gloves recommended due to severe corrosive properties
Water reactivity: Reacts violently with water producing toxic and corrosive fumes of hydrogen chloride and iodine vapor; generates significant heat. Recommended extinguishing: Dry chemical, dry sand, or carbon dioxide only; do not use water or foam.
ERG Guide 157 recommendation: ERG 157: isolate spill or leak area immediately for at least 50-100 meters in all directions; evacuate downwind areas if material is releasing vapors or fumes
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 157 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.