Why CO2?

Describes how carbon dioxide is metabolically produced and can therefore be associated with the presence of occupants. Also it is relatively easy and inexpensive to measure, and it is fairly stable. In principle CO2 can be used to evaluate the ventilation rate, determine the proportion of outdoor air that is blended with recirculated air and provide an indication of perceived indoor air quality. Goes on to discuss CO2 and toxicity, outdoor or background CO2 concentration, indoor concentration, steady state concentration, transient concentration, "perceived" indoor air quality, and measurement methods.