Carbon Dioxide

Carbon dioxide (CO2) colorless, odorless gas. It is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom.

Plant life uses CO2 during photosynthesis to make sugars, which can either be consumed by respiration or used as the raw material to produce other organic compounds needed for plant growth and development.

CO2 is also a byproduct formed by fossil fuel combustion, the burning of vegetable matter, and other chemical processes. It is also emitted by the dissolution of carbonates in crustal rocks.

For over a century, CO2 has been recognized as a workplace hazard. It is significantly heavier than air and many fatalities from asphyxiation have resulted from entry into pits, tanks, sumps or cellars where CO2 has accumulated and displaced oxygen.


Gas Carbon Dioxide Gas Density
Chemical Symbol CO2 Detection Principle IR
PEL (ppm) 5000 LEL (%)
IDHL (ppm) 30000 UEL (%)
Industries Food Processing, Pharmaceuticals, Manufacturing, Research, HVAC description


Industrial Applications


Carbon dioxide is used to produce carbonated soft drinks and soda water. Traditionally, the carbonation in beer and sparkling wine came about through natural fermentation, but today many of these are now artificially carbonated. Carbon dioxide in the form of dry ice is often used in the winemaking process to quickly cool down grapes after they are picked. CO2 is also used to decaffeinate coffee.


Leavening agents produce CO2 and cause dough to rise. Baker's yeast produces CO2 by fermentation of sugars within the dough, while chemical leaveners such as baking powder and baking soda release CO2 when heated or if exposed to acids.


Liquid and solid CO2 are important refrigerants, especially in the food industry, where they are employed during the transportation and storage of ice cream and other frozen foods.

Fire extinguishing

CO2 is widely used as an extinguishing agent in fixed fire protection systems for local application of specific hazards and total flooding of a protected space.


CO2 is used as an atmosphere for welding, although in the welding arc, it reacts to oxidize most metals. It is commonly used in the automotive industry.

Pharmaceutical and other chemical processing

Liquid CO2 is a good solvent for many lipophilic organic compounds. It is also used as an ingredient in the production of urea, carbonates, bicarbonates, and sodium salicylate.


Many greenhouses use CO2 to enrich the indoor atmosphere with additional CO2 to sustain plant life and promote growth. CO2 is also used at very high concentrations to eliminate pests.

Oil recovery

Carbon dioxide is used in enhanced oil recovery, whereby it is injected into or adjacent to producing oil wells, usually under supercritical conditions.

Coal bed methane recovery

In enhanced coal bed methane recovery, CO2 is pumped into the coal seam to displace methane.


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