The American Lung Association is concerned about the health impacts of marijuana use, especially on lung health, and caution the public against smoking marijuana because of the risks it poses to the lungs. Like tobacco smoke, marijuana smoke is an irritant to the throat and lungs and can cause a heavy cough during use. It also contains levels of volatile chemicals and tar that are similar to tobacco smoke, raising concerns about risk for cancer and lung disease.
Marijuana smoking is associated with
large airway inflammation, increased airway resistance, and lung
hyperinflation, and those who smoke marijuana regularly report more symptoms of
chronic bronchitis than those who do not smoke. Smoking marijuana may also
reduce the respiratory system’s immune response, increasing the likelihood of
the person acquiring respiratory infections, including pneumonia.
Whether smoking marijuana causes lung cancer, as cigarette smoking does, remains an open question. Marijuana smoke
contains carcinogenic combustion products, including about 50% more benzoprene
and 75% more benzanthracene (and more phenols, vinyl chlorides, nitrosamines,
reactive oxygen species) than cigarette smoke. Because of how it is typically
smoked (deeper inhale, held for longer), marijuana smoking leads to four times
the deposition of tar compared to cigarette smoking. However, well-designed population studies have
failed to find an increased risk of lung cancer associated with marijuana use.
