Andrew R Tomlinson1, Benjamin D Levine2, Tony G Babb3. 1. Division of Pulmonary and Critical Care Medicine, University of Texas Southwestern Medical Center, Dallas, TX; Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, TX. Electronic address: andrew.tomlinson@utsouthwestern.edu. 2. Division of Cardiology, University of Texas Southwestern Medical Center, Dallas, TX; Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, TX. 3. Division of Pulmonary and Critical Care Medicine, University of Texas Southwestern Medical Center, Dallas, TX; Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, TX.