Current ventilation guidelines, such as those from the Society of Heating Refrigerating, and Air Conditioning Engineers, recommend that indoor CO2 levels not exceed the local outdoor concentration by more than about 650 ppm. Good practice indicates that the ASHRAE Standard 62.1 target CO2 level in indoor air is about 1,030 ppm given the outside average of 380 ppm. It is important to adhere to these guidelines.
The performance of individuals in schools and offices with elevated CO2 concentrations can be affected because occupants may become lethargic and drowsy. Additionally, as CO2 builds up, so do other indoor air contaminants, which increases occupants’ exposures to irritating, distracting and potentially unhealthy gases and particulates