When is there too much CO2 in a building? Let’s take a look at the air quality inside a building. First, we must consider the carbon dioxide content CO2 of the air. The presence of carbon dioxide inside buildings is largely due to human respiration, because the metabolism of cells converts oxygen to CO2 when it is breathed out. A person at rest or a low level of activity will produce 0.7 g CO2 every minute.
The diagram shows some concentrations