In this article I will show how to measure carbon dioxide levels in your home. An important factor to test for when trying to measure indoor air quality (IAQ) is carbon dioxide. Tight homes with not enough ventilation and/or buildings with high occupancy are the usual candidates to having elevated carbon dioxide (CO2) levels, it is easy and low cost to measure CO2 levels. There is data from Lawrence Berkeley Lab that shows elevated indoor carbon dioxide (CO2) levels does impair cognitive abilities.
With that said it is important to remember carbon dioxide is only a part of a much larger indoor air quality picture. There are many contaminants that can be in the air in the following categories; particulate, biological, chemical / VOC, and gases. These are such things as dust mites, pollen, mold spores, mycotoxins, endotoxins, total VOCs, radon, and ozone just to name a few. These are all also influenced by temperature and humidity so only doing a carbon dioxide measurement is not going to give you enough data to have a good understanding of the state of your indoor air quality but it is a important data point.