R+D project promoted by Fluidra in collaboration with the Universitat Autònoma de Barcelona, the Hospital Clínic de Barcelona and hosted by the Club Natació Atlètic Barceloneta. Its main objective was to measure the improvement of the air quality in the swimming pool hall, achieved by a Fluidra’s new water treatment system, and to determine if such improvement would lead to a better physiologic response of the competitive swimmers to the physical endeavor. The sensing, monitoring and control system was designed and developed by Ctrl4 Enviro. We also participated in the design and execution of the experimental phase too.