Observation of Aerosol Generation by Human Subjects During Cardiopulmonary Exercise Testing Using a High-powered Laser Technique

Purpose: Human respiratory aerosols may have important implications for transmission of pathogens. The study of aerosol production during vigorous breathing activities such as exercise is limited. Data on aerosol production during cardiopulmonary exercise testing (CPET) are lacking. Methods: We used a high-powered, pulsed Nd:YAG laser to illuminate a region of interest in front of two healthy adult subjects during CPET. Subjects exercised to the point of respiratory compensation. Images were captured with a high-speed, high-resolution camera to determine net exhaled particle (NEP) counts at different phases of CPET, including resting breathing, submaximal exercise, peak exercise, and active recovery. Experiments were performed with the room ventilation activated.Results: NEP counts remained relatively constant until late/peak exercise when they decreased prior to rebounding into recovery. NEP counts at resting breathing were higher than those reported using other methods of measurement. Exhaled particles were in the submicron size range. Conclusion: Our method of aerosol particle quantification enables measurement of significant quantities of ultrafine particles and dynamic assessment of aerosol production during CPET. The unique pattern of aerosol production observed during submaximal and peak exercise suggests that extension of results from resting breathing to CPET may not be appropriate.