The inhalation of one marijuana cigarette (aka joint) per day over a 20-year period of time is not associated with adverse changes in lung health, according to a study published in the Annals of the American Thoracic Society journal.
Researchers assessed marijuana smoke exposure and lung health in a large sample of U.S. adults, ages 18 to 59. They reported that marijuana exposure was not associated with FEV1 (forced expiratory volume) decline or with any deleterious change in spirometric values of small airways disease.
The researchers noted, “The pattern of marijuana’s effects seems to be distinctly different when compared to that of tobacco use” and that “In a large representative sample of US adults, ongoing use of marijuana is associated with increased respiratory symptoms of bronchitis without a significant functional abnormality in spirometry, and cumulative marijuana use under 20 joint-years is not associated with significant effects on lung function.”
The study is the largest cross-sectional analysis to date that examined the relationship between marijuana use and spirometric parameters of lung health.
A different study published in 2012 in The Journal of the American Medical Association (JAMA) reported similar findings: cumulative marijuana smoke exposure over a period of up to 7 years (the equivalent of up to one marijuana cigarette per day for seven years) had no associated adverse effects on pulmonary function.
In a 2013 study published in the Annals of the American Thoracic Society, they acknowledged that marijuana smoke exposure was not associated with the development of lung cancer, emphysema, chronic obstructive pulmonary disease (COPD), or bullous lung disease. The study concluded: “Habitual use of marijuana alone does not appear to lead to significant abnormalities in lung function. Findings from a limited number of well-designed epidemiological studies do not suggest an increased risk of either lung or upper airway cancer from light or moderate use. … Overall, the risks of pulmonary complications of regular use of marijuana appear to be relatively small and far lower than those of tobacco smoking.”