Oxygen

1Identification

Name

Oxygen

IUPAC name

molecular oxygen

CAS number

7782-44-7

EC number

231-956-9

Molecular formula

O2

Molecular weight

31.999 g/mol

InChIKey

MYMOFIZGZYHOMD-UHFFFAOYSA-N

SMILES

O=O

PubChem CID

977

Synonyms

oxygen, Molecular oxygen, oxygen molecule, Dioxygen, Pure oxygen, Oxygenium, Liquid oxygen, Oxygen, liquified, Oxygen-16, Compressed oxygen, Oxygen, compressed, INS NO.948, INS-948, E-948

Recommended uses

• Used in steel furnaces, welding, metal cutting, metal hardening, rocket fuels, water treatment, medicine, and production of other chemicals; 21% of air; [CHEMINFO]
  Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
• Steel Producing [Category: Industry] Forging [Category: Heat or Machine] Heat Treating [Category: Heat or Machine] Gas Welding and Cutting [Category: Weld] Sewer and Wastewater Treatment [Category: Industry]
  Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
• Manufacturer of synthesis gas for production of ammonia, methyl alcohol, acetylene, etc; to counteract effect of eutrophication in lakes and reservoirs; coal gasification
  Hazardous Substances Data Bank (HSDB)
• Alloys Fuel agents
  EPA Chemical Data Reporting (CDR)
• Alloys Fuel agents
  EPA Chemical Data Reporting (CDR)

Use categories: Food additives · Food Additives -> PROPELLANT -> JECFA Functional Classes

Description

• Oxygen is a colorless, odorless and tasteless gas. It will support life. It is noncombustible, but will actively support the burning of combustible materials. Some materials that will not burn in air will burn in oxygen. Materials that burn in air will burn more vigorously in oxygen. As a non-liquid gas it is shipped at pressures of 2000 psig or above. Pure oxygen is nonflammable. Under prolonged exposure to fire or intense heat the containers may rupture violently and rocket. Oxygen is used in the production of synthesis gas from coal, for resuscitation and as an inhalant.
  CAMEO Chemicals
• Dioxygen is a gas molecular entity, an elemental molecule and a diatomic oxygen. It has a role as a micronutrient, a nutrient, a reagent, an anti-inflammatory drug, an oxidising agent, a Saccharomyces cerevisiae metabolite, a human metabolite and a member of food packaging gas. It is a conjugate base of a hydridodioxygen(1+).
  ChEBI
• Oxygen is an element displayed by the symbol O, and atomic number 8. It is an essential element for human survival. Decreased oxygen levels may be treated with medical oxygen therapy. Treatment with oxygen serves to increase blood oxygen levels and also exerts a secondary effect of decreasing blood flow resistance in the diseased lung, leading to decreased cardiovascular workload in an attempt to oxygenate the lungs. Oxygen therapy is used to treat emphysema, pneumonia, some heart disorders (congestive heart failure), some disorders that cause increased pulmonary artery pressure, and any disease that impairs the body's ability to take up and use gaseous oxygen.
  DrugBank

2Hazard identification

Signal word

Danger

Pictograms

GHS03, GHS04

Classification source

Regulation (EC) No 1272/2008 of the European Parliament and of the Council

Precautionary statements

Other reported classifications

5 classification records exist across sources. Differences usually reflect purity, physical form or impurities.

NFPA 704 rating

• 3 - Materials that, under emergency conditions, can cause serious or permanent injury.
  Hazardous Substances Data Bank (HSDB)
• 0 - Materials that will not burn under typical fire conditions, including intrinsically noncombustible materials such as concrete, stone, and sand.
  Hazardous Substances Data Bank (HSDB)
• 0 - Materials that in themselves are normally stable, even under fire conditions.
  Hazardous Substances Data Bank (HSDB)

Health hazards

• Inhalation of 100% oxygen can cause nausea, dizziness, irritation of lungs, pulmonary edema, pneumonia, and collapse. Liquid may cause frostbite of eyes and skin. (USCG, 1999)
  CAMEO Chemicals
• Excerpt from ERG Guide 122 [Gases - Oxidizing (Including Refrigerated Liquids)]: Vapors may cause dizziness or asphyxiation without warning, especially when in closed or confined areas. Contact with gas, liquefied gas or cryogenic liquids may cause burns, severe injury and/or frostbite. Fire may produce irritating and/or toxic gases. (ERG, 2024)
  CAMEO Chemicals
• · Vapors may cause dizziness or asphyxiation without warning, especially when in closed or confined areas. · Contact with gas, liquefied gas or cryogenic liquids may cause burns, severe injury and/or frostbite. · Fire may produce irritating and/or toxic gases.
  Emergency Response Guidebook (ERG)

Fire hazards

• Behavior in Fire: Increases intensity of any fire. Mixtures of liquid oxygen and any fuel are highly explosive. (USCG, 1999)
  CAMEO Chemicals
• Excerpt from ERG Guide 122 [Gases - Oxidizing (Including Refrigerated Liquids)]: Substance does not burn but will support combustion. Some may react explosively with fuels. May ignite combustibles (wood, paper, oil, clothing, etc.). Vapors from liquefied gas are initially heavier than air and spread along ground. Runoff may create fire or explosion hazard. Containers may explode when heated. Ruptured cylinders may rocket. (ERG, 2024)
  CAMEO Chemicals
• · Substance does not burn but will support combustion. · Some may react explosively with fuels. · May ignite combustibles (wood, paper, oil, clothing, etc.). · Vapors from liquefied gas are initially heavier than air and spread along ground. · Runoff may create fire or explosion hazard. · Containers may explode when heated. · Ruptured cylinders may rocket.
  Emergency Response Guidebook (ERG)

Hazards summary

• A powerful oxidizer and explosion hazard; Liquid may cause frostbite; Inhalation of 100% oxygen for 24 hours can cause pulmonary edema; Chronic exposure to high concentrations of oxygen can cause lung scarring; [CHEMINFO] Oxygen toxicity is observed in mechanically ventilated patients treated for hypoxic respiratory failure. Exposures to oxygen at FIO2 of 50 to 60% for more than 6 hours can cause lung injury including alveolar edema, formation of hyaline membranes, hypoxemia, and progressive fibrosis. [Cecil, p. 582]
  Haz-Map, Information on Hazardous Chemicals and Occupational Diseases

3Composition / information on ingredients

This page describes the pure substance. Commercial products may be solutions or mixtures. Check Section 3 of your supplier's SDS for concentrations and other ingredients.

4First-aid measures

• INHALATION: in all but the most severe cases (pneumonia), recovery is rapid after reduction of oxygen pressure; supportive treatment should include immediate sedation, anticonvulsive therapy if needed, and rest. EYES: treat frostbite burns. SKIN: treat frostbite; soak in lukewarm water. (USCG, 1999)
  CAMEO Chemicals
• Excerpt from ERG Guide 122 [Gases - Oxidizing (Including Refrigerated Liquids)]: Refer to the "General First Aid" section. Specific First Aid: Clothing frozen to the skin should be thawed before being removed. In case of contact with liquefied gas, only medical personnel should attempt thawing frosted parts. (ERG, 2024)
  CAMEO Chemicals
• General First Aid: · Call 911 or emergency medical service. · Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination. · Move victim to fresh air if it can be done safely. · Administer oxygen if breathing is difficult. · If victim is not breathing: -- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance. -- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped with a one-way valve or other device).
  Emergency Response Guidebook (ERG)

Symptoms of exposure

• Cough. Dizziness. Sore throat. Visual disturbances.
  ILO-WHO International Chemical Safety Cards (ICSCs)
• Cough. Dizziness. Sore throat.
  ILO-WHO International Chemical Safety Cards (ICSCs)
• ON CONTACT WITH LIQUID: FROSTBITE.
  ILO-WHO International Chemical Safety Cards (ICSCs)

5Fire-fighting measures

• LIQ: When fire results from a leak or flow of liq oxygen onto wood, paper, waste or another similar material, the first thing to do is stop flow if possible. For small spills, or after leak or flow of liq oxygen has been stopped, use enough water to put out fire quickly. When fire involves liq oxygen and liq fuels, control it as follows: (a) When liq oxygen leaks or flows into large quantities of fuel, shut off flow of liq oxygen, and put remaining fuel fire out with extinguishing agents suitable for use on class B fires. When fuel leaks or flows into large quantities of liq oxygen, shut off flow of fuel.
  Hazardous Substances Data Bank (HSDB)
• If material involved in fire: Dangerously explosive. Cool all affected containers with flooding quantities or water. Do not use water on material itself. Apply water from as far a distance as possible. /Oxygen, refrigerated liquid/
  Hazardous Substances Data Bank (HSDB)
• If material involved in fire: Dangerously explosive. Cool all affected containers with flooding quantities of water. Apply water from as far as distance as possible. /Oxygen, compressed/
  Hazardous Substances Data Bank (HSDB)

6Accidental release measures

Isolation and evacuation

• Excerpt from ERG Guide 122 [Gases - Oxidizing (Including Refrigerated Liquids)]: IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area for at least 100 meters (330 feet) in all directions. LARGE SPILL: Consider initial downwind evacuation for at least 500 meters (1/3 mile). FIRE: If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions. (ERG, 2024)
  CAMEO Chemicals
• Immediate precautionary measure · Isolate spill or leak area for at least 100 meters (330 feet) in all directions. Large Spill · Consider initial downwind evacuation for at least 500 meters (1/3 mile). Fire · If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions.
  Emergency Response Guidebook (ERG)

Spill cleanup

• Ventilation.
  ILO-WHO International Chemical Safety Cards (ICSCs)
• Notify safety personnel of significant leaks or spills. ... Shut off oxygen source if possible.
  Hazardous Substances Data Bank (HSDB)
• To increase the rate of controlled evaporation, spray with large amounts of water (fog may be generated and reduce visibility). /Liquid oxygen/
  Hazardous Substances Data Bank (HSDB)
• Eliminate all ignition sources. Stop or control the leak, if this can be done without undue risk. USe water spray to disperse vapors and protect personnel.
  Hazardous Substances Data Bank (HSDB)

7Handling and storage

• Fireproof. Separated from combustible substances and reducing agents. Cool.
  ILO-WHO International Chemical Safety Cards (ICSCs)
• GAS & LIQ: GASEOUS OXYGEN IS STORED ... IN CYLINDERS AT A PRESSURE OF 150-160 ATM, & INSULATED TANKS ARE USED FOR LIQUID OXYGEN; SMALL QUANTITIES OF LIQUID OXYGEN (2-50 L) CAN BE STORED IN DEWAR FLASKS.
  Hazardous Substances Data Bank (HSDB)
• Oxygen should be stored in an area that is at least 20 ft away from any flammable or combustible materials (especially oil & grease) or separated from them by a noncombustible barrier at least 5 ft high & having a fire-resistant rating of at least 1/2 hr.
  Hazardous Substances Data Bank (HSDB)
• LIQ: Protect against physical damage. Isolate from combustible gas installations and combustible materials by adequate distance or by gas-tight fire-resistive barriers. Protect against overheating. Outside storage of liq oxygen tanks is recommended.
  Hazardous Substances Data Bank (HSDB)

8Exposure controls / personal protection

No occupational exposure limits found in our sources.

Personal protective equipment

• Safety goggles or face shield; insulated gloves; long sleeves; trousers worn outside boots or over high-top shoes to shed spilled liquid. (USCG, 1999)
  CAMEO Chemicals
• Excerpt from ERG Guide 122 [Gases - Oxidizing (Including Refrigerated Liquids)]: Wear positive pressure self-contained breathing apparatus (SCBA). Wear chemical protective clothing that is specifically recommended by the manufacturer when there is NO RISK OF FIRE. Structural firefighters' protective clothing provides thermal protection but only limited chemical protection. Always wear thermal protective clothing when handling refrigerated/cryogenic liquids. (ERG, 2024)
  CAMEO Chemicals
• Liq: Safety goggles or face shield; insulated gloves; long sleeves; trousers worn outside boots or over high-top shoes to shed spilled liquid.
  Hazardous Substances Data Bank (HSDB)
• LIQ: Wear special protective clothing that will not ignite on contact with liq oxygen and that is designed to prevent liq ... from coming in contact with skin.
  Hazardous Substances Data Bank (HSDB)

9Physical and chemical properties

10Stability and reactivity

Reactivity

• Propellant; ignites upon contact with alcohols, alkali metals, amines, ammonia, beryllium alkyls, boranes, dicyanogen, hydrazines, hydrocarbons, hydrogen, nitroalkanes, powdered metals, silanes, or thiols [Bretherick 1979. p.174]. Heat of water will vigorously vaporize liquid oxygen, pressures may build to dangerous levels if this occurs in a closed container. Liquid oxygen gives a detonable mixture when combined with powdered aluminum [NFPA 491M. 1991].
  CAMEO Chemicals
• No rapid reaction with air. No rapid reaction with water.
  CAMEO Chemicals

Incompatible materials and hazardous reactions

• Liq: Heat of water will vigorously vaporize liquid oxygen.
  Hazardous Substances Data Bank (HSDB)
• Oxygen leaked into the free space in an acetaldehyde storage tank normally purged with nitrogen. Accelerating exothermic oxidation led to detonation. The self-ignition temperature of acetaldehyde-oxygen mixtures depends on dimensions of the reactor and the partial pressure of peracetic acid accumulated on the walls. Spontaneous ignition temperatures of 71 to 73 °C were observed.
  Hazardous Substances Data Bank (HSDB)
• Oxygen reacts explosively with phosphine, hydrazine, hydrogen sulfide ...
  Hazardous Substances Data Bank (HSDB)

11Toxicological information

Short-term exposure effects

• The substance at very high concentrations is irritating to the respiratory tract. The substance may cause effects on the central nervous system, lungs and eyes.
  ILO-WHO International Chemical Safety Cards (ICSCs)

Long-term exposure effects

• Repeated or prolonged inhalation of high concentrations may cause effects on the lungs.
  ILO-WHO International Chemical Safety Cards (ICSCs)

12Ecological information

Not available in the public sources we compile. Check Section 12 of the supplier's SDS.

13Disposal considerations

• SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal, aquatic, and plant life; and conformance with environmental and public health regulations.
  Hazardous Substances Data Bank (HSDB)
• Remove waste containers or leaking cylinders to exhaust hood or outdoors away from combustibles and allow to discharge at moderate rate. Tag cylinder to indicate defect, close valve and return to supplier. /Liquid and compressed oxygen/
  Hazardous Substances Data Bank (HSDB)
• Evaporation: Remove waste containers or leaking cylinders to exhaust hoods or outdoors away from combustibles and allow to discharge @ a moderate rate. Tag cylinder to indicate defect, close valve and return to supplier.
  Hazardous Substances Data Bank (HSDB)

14Transport information

UN numbers: UN 1072, UN 1073

Shipping name

• UN 1072; Oxygen, compressed
  Hazardous Substances Data Bank (HSDB)
• UN 1073; Oxygen, refrigerated liquid (cryogenic liquid)
  Hazardous Substances Data Bank (HSDB)

DOT hazard class

• Oxygen, compressed
  US Code of Federal Regulations, Hazardous Materials, 49 CFR Part 172
• UN1072
  US Code of Federal Regulations, Hazardous Materials, 49 CFR Part 172
• Div 2.2 Non-flammable compressed gas (49 eCFR § 173.115)
  US Code of Federal Regulations, Hazardous Materials, 49 CFR Part 172

DOT label

• Non-Flammable Gas Oxidizer
  CAMEO Chemicals

UN classification

• UN Hazard Class: 2.2; UN Subsidiary Risks: 5.1
  ILO-WHO International Chemical Safety Cards (ICSCs)

Emergency Response Guidebook

• 1072 122
  Emergency Response Guidebook (ERG)
• 1073 122
  Emergency Response Guidebook (ERG)

How DOT hazard classes work →

15Regulatory information

No specific US regulatory listings found in our sources. Check Section 15 of your supplier's SDS for TSCA, SARA 313, CERCLA, Prop 65 and state listings.

Overview of SDS regulations (OSHA HazCom, WHMIS, REACH/CLP) →

16Other information

Compiled from PubChem CID 977 and the sources it aggregates (attributed inline). Data retrieved 2026-10-12. This summary describes the pure substance and is not a supplier SDS.