An electrically-powered device intended to be used in a clinical setting and in the home to measure the concentration of exhaled carbon dioxide (CO2) in normal tidal breathing, using a particular method (e.g., infrared spectroscopy, gas chromatography), and to telemetrically send data to a remote server or local computer/tablet for viewing results and clinical evaluation by a healthcare professional. It consists of a hand-held sensor unit, a replaceable breath sampling chamber, and a breathing mouthpiece. It is used to help identify or assess cardio-respiratory conditions (e.g., chronic obstructive pulmonary disease, asthma, chronic heart failure).