The subject will spend two visits one hour each day (\~ 1 hour) in the PFT lab and will have two separate CPET (Vmax Encore PFT System, Vyaire medical, Mettawa, IL) tests performed by registered pulmonary function technologists. One day the test will be performed with the inline filter during CPET, and the second day the CPET will be performed without a filter. During the test, electrocardiogram (ECG) electrodes will be attached to participants as well as a mask, and their heart rate will be measured for 10 minutes at rest, and then they will ride bicycle for 20 minutes at different levels of intensity. The work rate increment will be the same for both tests. All gas exchange and aerosol particle concentrations measures will be compared with Bland Altman analysis and paired t-testing.
