Measuring and managing IAQ is a mandatory step in ensuring chosen healthy building measures (like bi-polar ionization and filtration) are working. Using CO2 as a proxy for healthy air is a good approach, and if used, it must be done with accurate technology. This includes calibrated sensors and differential measurement. However the “gold standard” approach to IAQ measurement and management is to combine the accurate technology with a multiple parameter approach including the measurement of total volatile organic compounds, humidity and particles. Through examining customer data we have seen many examples where CO2 levels don’t reflect an air quality issue within a room. In those cases if multi-parameter sensing is not used ventilation rates may not be increased as needed. Below are two instances that demonstrate measuring multiple parameters is needed to truly ensure healthy room ventilation.