Although a number of laws have legalized the use of marijuana across the nation, the substance is still considered a Schedule I drug-- defined by the DEA as "the most dangerous [category of] drugs" with no approved medical use. A new study from researchers at Emory University, however, indicates that longterm use may be less harmful than we thought.
"Lifetime marijuana use up to 20 joint-years is not associated with adverse changes in spirometric (exhalation strength) measures of lung health," reads the study, which was published in the Annals of the American Thoracic Society.
Think Progress' Sam P.K. Collins reports:
In an effort to measure marijuana's impact on lung function, researchers used data from the National Health and Nutrition Examination Surveys to conduct a cross-sectional analysis measuring participants' forced expiratory volume -- defined as the amount of air one can forcibly exhale in one second. They found that adults between the ages of 18 and 59 who smoke one marijuana cigarette, also known as a joint, per day had the same expiratory volume as someone who didn't partake in the plant.
The study echoes previous research that has found minimal effects of long term marijuana use, particularly when it comes to lung function. One such study from 2013, conducted by Donald P. Tashkin at UCLA, found "habitual use of marijuana alone does not appear to lead to significant abnormalities in lung function when assessed either cross-sectionally or longitudinally, except for possible increases in lung volumes and modest increases in airway resistance of unclear clinical significance.