U.S. Army Sgt. Valeria Melton, McDonald Army Health Center NCO in charge of internal medicine, trains Spc. Heaith Howe, McDonald Army Health Center radiology specialist, on how a Pulmonary Function Test machine works at Joint Base Langley-Eustis, Virginia, Feb. 5, 2019. The PFT machine is used to show the respiratory therapist how well the patient’s lungs are working. (U.S. Air Force photo by Senior Airman Tristan Biese)