Real-time system for monitoring the water vapour concentration and temperature of air exhaled from human lungs

This article describes a fully optoelectronic system for measuring the H2O concentration and temperature of air exhaled from human lungs. A device consisting of both a laser hygrometer and an ultra-fast resistive thermometer. It was tested during an experiment with saturated water vapour, confirming its accuracy for measuring H2O concentration in air. Data, from a preliminary investigation of breath samples from anonymous adult volunteers, is presented.