We are back live this week with a special guest, Pawel Wargocki, PhD of the Technical University of Denmark. Dr. Wargocki is a prolific researcher and has Chaired or been on just about every important IAQ committee and association in the world. Radio Joe got a chance to hear him speak at the 2017 IAQA Conference and had to get him on the show. Today we will discuss the questions, is CO2 a pollutant or merely an index for IAQ? Dr. Wargocki is an Associate Professor at the Technical University of Denmark; Past President of the International Society of Indoor Air Quality and Climate; Past Chair of ASHRAE Environmental Health Committee and the Position Document Committee; Vice President of Indoor Air 2008 Conference; Secretary of Academy of Indoor Air Sciences; incoming Director of the International Centre for Indoor Environment and Energy. He is a widely respected indoor climate scientist and expert, teacher at undergraduate, graduate and Ph.D. courses; supervisor of several Ph.D. and numerous M.Sc. students. His research has influenced development of indoor air sciences not least because of his studies on the effects of indoor environment on mental performance, on office work by adults and on schoolwork by children. He has carried out numerous laboratory chamber experiments with human subjects (equivalent to 5,000 subject hours) and field experiments (in more than 100 buildings).