- FEV1 greater 80% of predicted= normal
- FEV1 60% to 79% of predicted = Mild obstruction
- FEV1 40% to 59% of predicted = Moderate obstruction
- FEV1 less than 40% of predicted = Severe obstruction
National Heart, Lung, and Blood Institute. Accessed: January 1, 2009. Expert Panel Report 3 (EPR3): Guidelines for the Diagnosis and Management of Asthma
Clinical Pulmonary Function Testing, Exercise Testing, and Disability Evaluation. In Chest Medicine: Essentials Of Pulmonary And Critical Care Medicine. Editors: Ronald B. George, Richard W. Light, Richard A. Matthay, Michael A. Matthay. May 2005, 5th edition.