# NIOSH Pocket Guide to Chemical Hazards
Chlorine dioxide | CAS 10049-04-4
ClO2 | RTECS FO3000000
Synonyms & Trade Names Chlorine oxide, Chlorine peroxide | DOT ID & Guide 9191 143 (hydrate, frozen)
Exposure Limits | NIOSH REL: TWA 0.1 ppm (0.3 mg/m3) ST 0.3 ppm (0.9 mg/m3)
OSHA PEL†: TWA 0.1 ppm (0.3 mg/m3)
IDLH 5 ppm | Conversion 1 ppm = 2.76 mg/m3
Physical Description Yellow to red gas or a red-brown liquid (below 52°F) with an unpleasant odor similar to chlorine and nitric acid.
MW: 67.5 | BP: 52°F | FRZ: -74°F | Sol(77°F): 0.3%
VP: >1 atm | IP: 10.36 eV | RGasD: 2.33 | Sp.Gr: 1.6 (Liquid at 32°F)
Fl.P: NA (Gas) ? (Liquid) | UEL: ? | LEL: ? |
Flammable Gas/Combustible Liquid
Incompatibilities & Reactivities Organic materials, heat, phosphorus, potassium hydroxide, sulfur, mercury, carbon monoxide [Note: Unstable in light. A powerful oxidizer.]
Measurement Methods OSHA ID202
Personal Protection & Sanitation Skin: Prevent skin contact (liquid) Eyes: Prevent eye contact (liquid) Wash skin: When contaminated (liquid) Remove: When wet (flammable) Change: No recommendation Provide: Eyewash (liquid), Quick drench (liquid) | First Aid (See procedures) Eye: Irrigate immediately (liquid) Skin: Soap wash immediately (liquid) Breathing: Respiratory support Swallow: Medical attention immediately (liquid)
Respirator Recommendations NIOSH/OSHA Up to 1 ppm: (APF = 10) Any chemical cartridge respirator with cartridge(s) providing protection against the compound of concern/(APF = 10) Any supplied-air respirator Up to 2.5 ppm: (APF = 25) Any supplied-air respirator operated in a continuous-flow mode£/(APF = 25) Any powered, air-purifying respirator with cartridge(s) providing protection against the compound of concern£ Up to 5 ppm: (APF = 50) Any chemical cartridge respirator with a full facepiece and cartridge(s) providing protection against the compound of concern/(APF = 50) Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted canister providing protection against the compound of concern/(APF = 50) Any self-contained breathing apparatus with a full facepiece/(APF = 50) Any supplied-air respirator with a full facepiece Emergency or planned entry into unknown concentrations or IDLH conditions: (APF = 10,000) Any self-contained breathing apparatus that has a full facepiece and is operated in a pressure- demand or other positive-pressure mode/(APF = 10,000) Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode in combination with an auxiliary self-contained positive-pressure breathing apparatus Escape: (APF = 50) Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted canister providing protection against the compound of concern¿/Any appropriate escape-type, self-contained breathing apparatus
Exposure Routes inhalation, ingestion (liquid), skin and/or eye contact
Symptoms Irritation eyes, nose, throat; cough, wheezing, bronchitis, pulmonary edema; chronic bronchitis
Target Organs Eyes, respiratory system
See also: INTRODUCTION