Marijuana use doesn’t damage lungs study claims

Eric Pfeiffer

A new study published by the Journal of the American Medical Association reports that moderate marijuana use (2-3 times per month) is not linked with lung damage. Even more surprising, the study actually found that the moderate use increased lung capacity in a plurality of the study participants.

By comparison, cigarette smokers showed a measurable decrease in health during the same study, which was conducted over 20 years amongst more than 5,000 participants. "FEV1 and FVC both actually increased with moderate and occasional use of marijuana," says Dr. Mark Pletcher, associate professor of epidemiology and biostatistics at the University of California, San Francisco and the lead author of the study.

More from the study results:

While tobacco smokers showed the expected drop in lung function over time, the new research found that marijuana smoke had unexpected and apparently positive effects.  Low to moderate users actually showed increased lung capacity compared to nonsmokers on two tests, known as FEV1 and FVC. FEV1 is the amount of air someone breathes out in the first second after taking the deepest possible breath; FVC is the total volume of air exhaled after the deepest inhalation.

That was a bit of a surprise, says Pletcher, since "There are clearly adverse effects from tobacco use and marijuana smoke has a lot of the same constituents as tobacco smoke does so we thought it might have some of the same harmful effects. It's a weird effect to see and we couldn't make it go away," he adds, explaining that the researchers used statistical models to look for errors or other factors that could explain the apparent benefit and did not find them.

The study's conclusion finds, "Occasional and low cumulative marijuana use was not associated with adverse effects on pulmonary function." Research for the study was done by researchers at the University of California, San Francisco, and the University of Alabama at Birmingham.

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