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Understanding Carbon Dioxide Hazards

Carbon dioxide (CO2) is used in a wide range of applications. It is unique because it is commercially used in several forms: as a gas for applications such as carbonation, purging, and pH control; as a liquid for applications including food processing and fire suppression; as a solid for applications such as expendable refrigeration and chilling; and as a supercritical fluid for applications including specialized extraction processes for substances such as caffeine and cannabis.

Dry ice is the solid form of carbon dioxide. It is used extensively as a cooling agent in a variety of applications such as food chilling and freezing, vaccine cooling, expendable refrigeration, blood and tissue sample preservation, metal heat treating processes, and many more. It is also sometimes used to create special effects such as fog for events or stage presentations.

Anyone who handles carbon dioxide should be aware of its unique properties and potential hazards. Carbon dioxide is 1.5 times heavier than air and tends to accumulate in low or confined areas. It can displace oxygen and cause rapid suffocation as well as other serious physiological effects.

In addition, carbon dioxide can pose additional hazards such as exposure to extremely cold vapors or liquid or dry ice blockage of piping depending on its physical state.

The container label and safety data sheet (SDS) provide detailed hazard information and handling precautions. Always read and understand the label and the SDS before using any product and follow the instructions and safety precautions provided by your product supplier. These safety posters, provided by the Compressed Gas Association, provide basic safety information about the hazards associated with carbon dioxide. To learn more, see the section, “Product Information: Carbon Dioxide” at the bottom of this page.

Carbon Dioxide Safety Reminders

Carbon dioxide can create a hazardous atmosphere.

  • Recognize and be aware of areas where carbon dioxide can accumulate.

  • Monitor and ventilate for carbon dioxide as required by code.

  • Never modify or tamper with carbon dioxide systems or equipment.

  • Use required personal protective equipment (PPE) when working with carbon dioxide.

  • Never enter an area of high carbon dioxide concentration without proper personal protective equipment (PPE).

Poster Downloads

Solvent Direct offers safety posters as educational resources to support the safe use of our industry’s products and equipment. It is important to note that these posters are not a substitute for reading and following codes and regulations, industry standards, and supplier instructions. Purchase your carbon dioxide safety poster today or the full set.


Product Information:



Carbon dioxide (CO2) is a compound of carbon and oxygen. A gas at normal atmospheric pressures and temperatures, carbon dioxide is colorless, odorless, slightly acidic, and about 1.5 times heavier than air. It can exist simultaneously at its triple point as a solid (dry ice), liquid, and gas at a temperature of –69.9 °F (–56.6 °C) and a pressure of 60.4 psig (416 kPa). At temperatures and pressures below the triple point, carbon dioxide can be either a solid or a gas, depending upon temperature conditions. At temperatures and pressures above the triple point and below 87.9 °F (31.1 °C), carbon dioxide liquid and gas can exist in equilibrium in a closed container. The solubility of carbon dioxide in water varies with temperature and pressure.

Carbon dioxide does not support life and can be dangerous even when adequate oxygen is available.


Personnel handling carbon dioxide shall be thoroughly familiar with its associated hazards. There are several conditions in which extreme danger to personnel and equipment can exist, including:

  • employee exposure to extremely cold liquid, vapor, dry ice, piping, or equipment which can cause severe damage to eyes or skin;

  • dry ice blocking hoses, pipes, or valves which can result in an overpressurization, forceful ejection of the plug, and/or hose whip;

  • low temperature effects on the container, piping, hoses, and other system components which can cause material changes such as embrittlement, shrinking, or swelling and can result in failure (see G-6.1, Standard for Insulated Liquid Carbon Dioxide Systems at Consumer Sites);

  • vaporization of liquid that is trapped (e.g., in a hose, piping, or within a valve) will result in increased pressure that can result in a rupture;

  • dry ice obstructions in discharge and blowdown piping, which can lead to the unintended pressurization of piping or components to greater than the design pressures and colder than the design temperatures;

  • personnel overexposure to carbon dioxide which can result in serious injury or death;

  • overfilling cylinders and containers which can result in overpressurization and can cause the cylinder or container to rupture; and

  • generation of extremely high static electricity charges (greater than 100,000 volts) during the formation of solid dry ice, which can present serious hazards particularly in combustible environments.

It is critical that all personnel working with carbon dioxide understand the potential hazards and follow industry guidelines for safe practices. More information regarding these potential safety hazards and recommended mitigations are addressed in CGA G-6, Carbon Dioxide. Precautions for handling dry ice are found in CGA G-6.9, Dry Ice, and CGA SP-15, Safety Poster (End User), Safe Handling, Transport, and Use of Dry Ice.


Ventilate adjacent enclosed areas to prevent the formation of dangerous concentrations of carbon dioxide. Personnel including rescue workers should not enter areas in which the carbon dioxide content exceeds 3% by measurement unless wearing an SCBA or supplied-air respirators.

Avoid contact of the skin or eyes with solid carbon dioxide (dry ice) or objects cooled by solid carbon dioxide.

For supplemental environmental and regulatory information on carbon dioxide leaks and venting since carbon dioxide is a greenhouse gas, refer to CGA P-37, Good Environmental Management Practices for the Compressed Gas Industry, and CGA P-63, Disposal of Gases.



Do not attempt to remove anyone exposed to high concentrations of carbon dioxide without using proper rescue equipment or the potential rescuer could also become a casualty. Rescuers account for over 60% of confined space fatalities. If the exposed person is unconscious, obtain assistance and use established emergency procedures.

Inhalation. Persons who have inhaled large amounts of carbon dioxide and are exhibiting adverse effects such as rapid respiration and headaches should be removed to fresh air immediately, if safe to do so. Perform artificial respiration if breathing has stopped. Keep the victim warm and at rest and obtain medical attention at once. Fresh air and assisted breathing (if required) is appropriate for all cases of overexposure. Recovery is usually complete with no residual effects.

Skin contact. In case of frostbite from contact with dry ice or cold gases, place the frostbitten part in warm water, 100 °F to 105 °F (37.8 °C to 40.6 °C). If warm water is not available or is impractical to use, wrap the affected part gently in blankets. Do not rub. Consult a physician.

Eye contact. If the eyes are involved, obtain prompt medical attention. The only appropriate first aid measure is a soft sterile pad held in place over both eyes.


Carbon dioxide is normally present in the atmosphere at about 0.035% by volume. It is also a normal end-product of human and animal metabolism. The greatest physiological effect of carbon dioxide is to stimulate the respiratory center, thereby controlling the volume and rate of respiration. It is able to cause dilation and constriction of blood vessels and is a vital constituent of the acid-base mechanism that controls the pH of the blood.

Carbon dioxide acts as a stimulant and a depressant on the central nervous system. Increases in heart rate and blood pressure have been noted at a concentration of 7.6% in air, and dyspnea (labored breathing), headache, dizziness, and sweating occur if exposure at that level is prolonged. At concentrations of 10% and above, unconsciousness can result in 1 minute or less. Impairment in performance has been noted during prolonged exposure to concentrations of 3% carbon dioxide even when the oxygen concentration was 21%.

Gaseous carbon dioxide is an asphyxiant. Concentrations of 10% or more can produce unconsciousness or death. Lower concentrations can cause headache, sweating, rapid breathing, increased heartbeat, shortness of breath, dizziness, mental depression, visual disturbances, and shaking. The seriousness of the latter manifestations are dependent upon the concentration of carbon dioxide and the length of time the individual is exposed.

OSHA provides a list of occupational exposure limits (OELs) for carbon dioxide. Please refer to OSHA’s website for more information.


  • Chemical formula = CO2

  • Molecular weight = 44.01

Vapor pressure

U.S. Units

  • at 70 °F = 838 psig

  • at 32 °F = 491 psig

  • at 2 °F = 302 psig

  • at –20 °F = 200 psig

  • at –69.9 °F = 60.4 psig

  • at –109 3 °F = 0 psig

SI Units

  • at 21.1 °C = 5778 kPa

  • at 0 °C = 3385 kPa

  • at –16.7 °C = 2082 kPa

  • at –28.9 °C = 1379 kPa

  • at –56.6 °C = 416 kPa

  • at –78.5 °C = 0 kPa

Density of the gas

U.S. Units

  • at 70 °F and 1 atm = 0.1144 lb/ft

  • at 32 °F and 1 atm = 0.1234 lb/ft

SI Units

  • at 21.1 °C and 1 atm = 31.833 kg/m3

  • at 0 °C and 1 atm = 31.977 kg/m3

Specific gravity of the gas

U.S. Units

  • at 70 °F and 1 atm = 1.522

  • at 32 °F and 1 atm = 1.524

SI Units

  • at 21.1 °C and 1 atm = 1.522

  • at 0 °C and 1 atm = 1.524

Specific volume of the gas

U.S. Units

  • at 70 °F and 1 atm = 8.741 ft3/lb

  • at 32 °F and 1 atm = 8.104 ft3/lb

SI Units

  • at 21.1 °C and 1 atm = 0.5457 m3/kg

  • at 0 °C and 1 atm = 0.5059 m3/kg

Density of the liquid, saturated

U.S. Units

  • at 70 °F  = 47.6 lb/ft

  • at 32 °F = 58.0 lb/ft

  • at 2 °F = 63.3 lb/ft

  • at –20 °F = 66.8 lb/ft

  • at –69.9 °F = 73.5 lb/ft

SI Units

  • at 21.1 °C = 3762 kg/m3

  • at 0 °C = 3929 kg/m3

  • at –16.7 °C = 31014 kg/m3

  • at –28.9 °C = 31070 kg/m3

  • at –56.6 °C = 31177 kg/m3

Latent heat of vaporization

U.S. Units

  • at 32 °F = 100.8 Btu/lb

  • at 2 °F = 119.0 Btu/lb

  • at –20 °F = 129.7 Btu/lb

SI Units

  • at 0 °C = 234.5 kJ/kg

  • at–16.7 °C = 276.8 kJ/kg

  • at –28.9 °C = 301.7 kJ/kg

Cylinder pressure at 68% filling density = 42.5 lb/ft3

U.S. Units

  • at 70 °F = 838 psig

  • at 100 °F = 1450 psig

  • at 130 °F = 2250 psig

Cylinder pressure at 68% filling density = 681 kg/m3

SI Units

  • at 21.1 °C = 5778 kPa

  • at 37.8 °C = 9998 kPa

  • at 54.4 °C = 15 514 kPa

Specific heat of the gas at 77 °F (25.0 °C) and 1 atm

U.S. Units

  • Cp = 0.203 Btu/(lb)(°F)

  • Cv = 0.157 Btu/(lb)(°F)

  • Ratio of specific heats (Cp/Cv) at 59 °F = 1.304

SI Units

  • Cp = 0.850 kJ/(kg)(°C)

  • Cv = 0.657 kJ/(kg)(°C)

  • Ratio of specific heats (Cp/Cv) at 15.0 °C = 1.304


U.S. Units

  • Sublimation temperature at 1 atm = –109.3 °F

  • Critical temperature = 87.9 °F

  • Critical pressure = 1070.6 psia

  • Critical density = 29.2 lb/ft

  • Triple point = –69.9 °F at 60.4 psig

  • Latent heat of fusion at –69.9 °F = 85.6 Btu/lb

  • Solubility in water, vol/vol at 68 °F = 0.90

  • Weight of the liquid at 2 °F = 8.46 lb/gal

  • Latent heat of sublimation at –109.3 °F = 245.5 Btu/lb

  • Viscosity of saturated liquid at 2 °F = 0.287 lb/(ft)(hr)

SI Units

  • Sublimation temperature at 1 atm = –78.5 °C

  • Critical temperature = 31.1 °C

  • Critical pressure = 7381.8 kPa

  • Critical density = 3468 kg/m3

  • Triple point = –56.6 °C at 416 kPa

  • Latent heat of fusion at –56.6 °C = 199 kJ/kg

  • Solubility in water, vol/vol at 20.0 °C = 0.90

  • Weight of the liquid at –16.7 °C = 1014 kg/m3

  • Latent heat of sublimation at –78.5 °C = 571.3 kJ/kg

  • Viscosity of saturated liquid at –16.7 °C = 0.000119 Pa•s



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