New Study: Marijuana Smoke Exposure Not Linked To Poor Lung Health

COLORADO:  Long-term exposure to cannabis smoke is not associated with significant adverse effects on pulmonary function, according to clinical data published in the journal Chronic Obstructive Pulmonary Diseases.

A team of investigators led by researchers at the Colorado School of Public Health assessed the relationship between marijuana use and respiratory function in a cohort of 2,300 subjects ages 40 to 80, many of whom also smoked tobacco.

Authors reported, “Neither current nor former marijuana use was associated with increased risk of cough, wheeze, or chronic bronchitis when compared to never marijuana users. … Current and former marijuana smokers had significantly higher FEV1 (forced expiratory volume) … when compared to never users. … Both current and former marijuana use was associated with significantly less quantitative emphysema … when compared to never users, even after adjusting for age, … current tobacco smoking pack years, and BMI. … In agreement with other published studies, we also did not find that marijuana use was associated with more obstructive lung disease.”

Researchers also reported that the long-term combined use of tobacco and cannabis was not associated with any additive adverse effects on the lungs. They concluded, “Among older adults with a history of tobacco use, marijuana use does not appear to increase risk for adverse lung function. … There may be no to little increased risk of marijuana use for a further increase in respiratory symptoms or adverse effects … among those with a history of concomitant tobacco use.”

Prior longitudinal studies assessing the effects of long-term cannabis smoke exposure on lung function have similarly reported that subjects’ marijuana use history is not positively associated with increased incidences of chronic obstructive pulmonary disease (COPD), lung cancer, or with other significant detrimental effects on pulmonary function.

For more information, contact Paul Armentano, NORML Deputy Director, at: Full text of the study, “Marijuana use associations with pulmonary symptoms and function in tobacco smokers enrolled in the subpopulations and intermediate outcome measures in COPD Study (SPIROMICS),” appears in Chronic Obstructive Pulmonary Diseases.

Read full article @ NORML


  1. Chris says

    I find it hard to believe cannabis smokers displayed higher FEV1 than non-smokers…possibly tobacco only smokers, but some level of obstruction will occur over time with chronic use.

  2. Mary Kay says

    Possibly, some of the reason for the difference is (1) Commercial tobacco, packaged as name-brand cigarettes, has dozens of additives, possibly more, collectively known as “tar.” I haven’t smoked anything for years, so I don’t even know if the manufacturers are still required to report the content of both tar and nicotine per cigarette. Now as far as I know, the only additive you may find in marijuana is paraquat, which I think the U.S. government would spray on the crops for a time in the 1970s, I think it was a pesticide, and I don’t know why they would want to kill bugs on weed, if not to discourage the growers from using it. I don’t know if paraquat is still sprayed on marijuana crops. Other than that, the only foreign ingredient you were inhaling was the paper, usually plain white or light brown, unless you were using one of the groovy colorful rainbow papers, which would be dyed, no match for the additives in Big Tobacco. You can also use a pipe to smoke marijuana, which requires no paper at all; or a bong, in which the smoke is filtered through water; (2) The active ingredient in marijuana, THC, can be ingested in an effective concentration in one or two rolled cigarettes, or joints, and the effect lasts for several hours. It does not produce a physical addiction like tobacco (although there may be a psychological dependency), nor does it encourage the nervous habit of always having a cigarette in your hand. The bottom line: a marijuana user is inhaling far less actual smoke than a cigarette smoker.

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