 We will utilize normal subjects for the control study for the Diffusion Capacity of Lung for Carbon Monoxide DLCO and Diffusion capacity of Lung for Nitric Oxide DLNO, recruited from the general population. We will recruit 5 males and 5 females in each decade of life from 21-30, 31-40, 41-50, 51-60, 61-70 TOTAL 50 subjects. 