Emily EarlenbaughContributor I cover cannabis’ intersection with science, culture, and wellness.
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Smoking cannabis was not associated with impaired lung functioning for young adults in a new longitudinal study published in Respiratory Medicine. In contrast to another recent study suggesting that smoking cannabis is more likely to cause emphysema than smoking tobacco, researchers in this study found that smoking cannabis alone was not tied to reduced airflow or impaired lung functioning. Still limitations in both studies suggest that we still don’t have a clear picture of smoked cannabis’ effect on our lungs.
This new study, from researchers at University of Queensland in Australia, examined whether chronic cannabis smoking was associated with damaging effects on the lungs of young adults, specifically. “Cannabis use is increasingly legalized and use is becoming normalized.” Lead author Professor Jake Najman explains. “In this context, understanding more about the harms associated with long-term cannabis use is important.”
To investigate this, researchers followed a cohort of 1173 young adults from age 21 to age 30, testing their lung function using a spirometry assessment at the beginning and end of the 9 year period. Spirometry tests are commonly used to help diagnose lung conditions, like asthma and COPD, by measuring the amount of air someone can breathe out in one forced breath. This is done with a device called a spirometer, which has a mouthpiece the patient can breathe into.
Researchers also tracked whether the members of the cohort smoked cannabis, tobacco, both or nothing over the 9 years. This was done using questionnaires at age 21 and 30, when the lung function tests were performed. Afterwards researchers analyzed the data to see whether cannabis smoking over 9 years had reduced lung function.
The results showed the expected association between tobacco smokers and reduced airflow. Those who smoked cigarettes alone, or cigarettes with cannabis, had reductions in their airflow over the 9 year period. Cannabis did not add to these reductions, over and above what was already found for tobacco only smokers. But perhaps surprisingly, in light of the recent findings on cannabis and emphysema, smoking cannabis alone did not reduce airflow or seem to impact lung functioning. Even after 9 years of use, cannabis smoke exposure did not seem to impact the lungs.
The authors concluded that “cannabis does not appear to be related to lung function, even after years of use.” They also concluded that using cannabis with tobacco doesn’t seem to add any additional risk to the lungs, beyond the harms already associated with smoking tobacco.