- Carbon dioxide is a chemical compound with the formula CO2, which is composed of one carbon atom and two oxygen atoms.

- It is a colorless, odorless, non-flammable, and relatively water-soluble gas.

- CO2 is heavier than air and can sink into low-lying areas, including basements and cellars, where it can displace oxygen.

- Carbon dioxide is a natural component of the earth's atmosphere and is produced by the respiration of animals and plants.

- It is also produced by industrial processes, such as the burning of fossil fuels, such as coal, oil and gas, which releases large amounts of CO2 into the atmosphere.

- CO2 contributes to the greenhouse effect by trapping heat in the earth's atmosphere.

- It is also a major source of ocean acidification, as it reacts with seawater to form carbonic acid, lowering the pH of the water.