What happens to CO2 levels when more air is added to a fire?

When more air is added to a fire, the combustion process becomes more efficient due to the increased availability of oxygen. In this scenario, oxygen levels rise as it is introduced into the combustion environment. As the combustion process occurs with more oxygen, it leads to a more complete oxidation of the fuel, which results in a reduction of carbon dioxide (CO2) levels produced during combustion.

As oxygen (O2) is used up to combust the fuel, this results in an increased presence of oxygen in the immediate environment while simultaneously reducing the concentrations of carbon dioxide that would typically be generated from incomplete combustion at lower oxygen levels. This dynamic reflects the balance of combustion where efficient burning consumes fuel and oxygen creating CO2 and other by-products.

The option that describes this scenario accurately highlights that CO2 goes down and O2 goes up, illustrating the direct relationship between the availability of air, fuel combustion, and the resulting gases emitted.