The Effects of Marijuana Exposure on Expiratory Airflow. A Study of Adults who Participated in the U.S. National Health and Nutrition Examination Study

Rationale: Given the inconclusive science on the long-term effects of marijuana exposure on lung function, the increasing tetrahydrocannabinol composition of marijuana over time, and the increasing legal accessibility of the substance, continued investigation is needed.Objectives: To determine the independent association between recent and chronic marijuana smoke exposure with spirometric parameters of lung function and symptoms of respiratory health in a large cohort of U.S. adults.Methods: This is a cross-sectional study of U.S. adults who participated in the National Health and Nutrition Examination Survey cycles from 2007–2008 and 2009–2010, using the data from standardized spirometry and survey questions performed during these years.Measurements and Main Results: In the combined 2007–2010 cohort, 59.1% replied that they had used marijuana at least once, and 12.2% had used in the past month. For each additional day of marijuana use in the prior month, there were no changes in percent predicted FEV1 (0...