Carbon dioxide (CO2) is a byproduct of human metabolism and exists in high levels in exhaled air, and is therefore often used as a proxy for indoor air quality. The study “Ventilation Assessment by Carbon Dioxide Levels in Dental Treatment Rooms,” published in the Journal of Dental Research (JDR), evaluated CO2 levels in dental operatories and determined the accuracy of using CO2 levels to assess ventilation rate in dental clinics.