Vaped, Smoked or Both: Cannabis and Young Adults' Lungs

Analysis. A study in the American Journal of Preventive Medicine followed 5,211 U.S. young adults aged 18 to 24 and asked who developed new breathing symptoms. Smoking cannabis, and above all smoking and vaping it, was linked to higher odds. Vaping alone showed no clear link, but too few people only vaped for that to mean much.

What the researchers did

The team, from the University of Alabama at Birmingham, UCSF, the University of Waterloo and the University of Michigan, used the national Population Assessment of Tobacco and Health (PATH) Study. They kept young adults who had no respiratory or pulmonary condition at Wave 6 and completed Wave 7. Data were collected between 2021 and 2023. The researchers then adjusted for demographics, other substance use, health conditions, obesity and how often people used cannabis.

At baseline, 18.8% reported cannabis vaping or smoking in the past 30 days: 2.1% vaped only, 11.3% smoked only and 5.3% did both. At follow-up, 2.3% of all participants reported the onset of functionally important respiratory symptoms.

What they found

Compared with no cannabis vaping or smoking, vaping only was not associated with symptoms (adjusted odds ratio 0.93, 95% confidence interval 0.20 to 4.43). Smoking only was (AOR 3.04, CI 1.64 to 5.64), and so was dual use (AOR 4.36, CI 2.12 to 8.96).

What the headlines leave out

An odds ratio is not a risk, and only 2.3% of participants developed symptoms, so the absolute numbers are small. The vaping-only group was about 2% of the sample, which is why its confidence interval runs from 0.20 to 4.43: it is compatible with a lower odds, no change or a much higher one. No link in a small group is not the same as no harm.

The design is observational and habits were self-reported, so it cannot show that cannabis caused the symptoms. The authors write that the findings must be considered preliminary and that more detailed data on use patterns, products and co-use with tobacco are needed.

The questions that remain

How large would a vaping-only group need to be to settle the question? Do the results hold once product type and potency are measured? And how much of the smoking-only signal is really tobacco? This article is not medical advice.