Smoking Marijuana May Be Worse for Lungs Than Smoking Cigarettes

Smoking Marijuana Joint

Airway inflammation and emphysema are more common in marijuana smokers than cigarette smokers, according to new research.

Emphysema More Common in Marijuana Smokers Than Cigarette Smokers

According to new research, airway inflammation and emphysema are more common in marijuana smokers than cigarette smokers. Investigators said the difference may be due to the way that marijuana is smoked and the fact that marijuana smoke enters the lungs unfiltered. The research study was published on November 15 in Radiology, a journal of the Radiological Society of North America (RSNA).

Marijuana is the most-commonly smoked substance after tobacco and one of the most widely used psychoactive substances in the world. Amid the legalization of recreational marijuana in Canada and many states in the U.S., its use has increased substantially in recent years. With the growing use, there is an urgent need for information on marijuana’s effects on the lungs, something that is currently lacking.

“It has been suggested that smoking a marijuana joint deposits four times more particulates in the lung than an average tobacco cigarette.” — Giselle Revah, M.D.

“We know what cigarettes do to the lungs,” said study author Giselle Revah, M.D., a cardiothoracic radiologist and assistant professor at the University of Ottawa in Ottawa, Canada. “There are well-researched and established findings of cigarette smoking on the lungs. Marijuana we know very little about.”

To find out more, Dr. Revah and colleagues compared chest CT results from 56 marijuana smokers with those of 57 non-smoking controls and 33 tobacco-only smokers.

Three-quarters of the marijuana smokers had emphysema, a lung disease that causes difficulty with breathing, compared with 67% of the tobacco-only smokers. Only 5% of the non-smokers had emphysema. Paraseptal emphysema, which damages the tiny ducts that connect to the air sacs in the lungs, was the predominant emphysema subtype in marijuana smokers compared to the tobacco-only group.

Airway Changes in Marijuana and Tobacco Smoker

Airway changes in a 66-year-old male marijuana and tobacco smoker. Contrast-enhanced (A) axial and (B) coronal CT images show cylindrical bronchiectasis and bronchial wall thickening (arrowheads) in multiple lung lobes bilaterally in a background of paraseptal (arrows) and centrilobular emphysema. Credit: Radiological Society of North America

Airway inflammation was also more common in marijuana smokers than non-smokers and tobacco-only smokers. The same was true for gynecomastia, a condition of enlarged male breast tissue due to a hormone imbalance. Gynecomastia was found in 38% of the marijuana smokers, compared with just 11% of the tobacco-only smokers and 16% of the controls.

The researchers found similar results among age-matched subgroups, where the rates of emphysema and airway inflammation were again higher in the marijuana smokers than the tobacco-only smokers.

There was no difference in coronary artery calcification between age-matched marijuana and tobacco-only groups.

According to Dr. Revah, the results were surprising, especially considering that the patients in the tobacco-only group had an extensive smoking history.

Pulmonary Emphysema in Marijuana and Tobacco Smokers

Pulmonary emphysema in (A, B) marijuana and (C, D) tobacco smokers. (A) Axial and (B) coronal CT images in a 44-year-old male marijuana smoker show paraseptal emphysema (arrowheads) in bilateral upper lobes. (C) Axial and (D) coronal CT images in a 66-year-old female tobacco smoker with centrilobular emphysema represented by areas of centrilobular lucency (arrowheads). Credit: Radiological Society of North America

“The fact that our marijuana smokers—some of whom also smoked tobacco—had additional findings of airway inflammation/chronic bronchitis suggests that marijuana has additional synergistic effects on the lungs above tobacco,” she said. “In addition, our results were still significant when we compared the non-age-matched groups, including younger patients who smoked marijuana and who presumably had less lifetime exposure to cigarette smoke.”

According to the CDC, 48.2 million people, or about 18% of Americans, used marijuana at least once in 2019.

There are likely several factors that contribute to the differences between the two groups. Marijuana is smoked unfiltered, Dr. Revah noted, while tobacco cigarettes are usually filtered. This results in more particulates reaching the airways from smoking marijuana.

In addition, marijuana is inhaled with a longer breath hold and puff volume than tobacco smoke.

“It has been suggested that smoking a marijuana joint deposits four times more particulates in the lung than an average tobacco cigarette,” Dr. Revah said. “These particulates are likely airway irritants.”

The higher incidence of emphysema may also be due to the way that marijuana is smoked. Full inhalation with a sustained Valsalva maneuver, an attempt at exhalation against a closed airway, may lead to trauma and peripheral airspace changes.

More research is needed, Dr. Revah said, with larger groups of people and more data on how much and how often people are smoking. Future research could also look at the impact of different inhalation techniques, such as through a bong, a joint, or a pipe.

“It would be interesting to see if the inhalation method makes a difference,” Dr. Revah said.

For more on this research, see Emphysema More Common in Marijuana Smokers Than Cigarette Smokers.

Reference: “Chest CT Findings in Marijuana Smokers” by Luke Murtha, Paul Sathiadoss, Jean-Paul Salameh, Matthew D. F. Mcinnes and Giselle Revah, 15 November 2022, Radiology.
DOI: 10.1148/radiol.212611

25 Comments on "Smoking Marijuana May Be Worse for Lungs Than Smoking Cigarettes"

  1. RICHARD K PRICE | November 17, 2022 at 4:08 am | Reply

    I have heard so much false pro-drug war hype and rhetoric about anti-marijuana that I can no longer give any credence or credibility to those organizations that take their grant funding from the government. I simply do not believe these “so-called” findings. The government is well known to give vastly preferential funding to support its war on marijuana. There are other studies that prove marijuana does not harm smokers. OF COURSE, there are always exceptions that only reveal that it is impossible to idiot-proof anything. This should be called “The Idiot Factor”.

  2. this article was brought to you by marlboro; inhale the studies, exhale the the safety.

    I mean, science has become a farce tainted by the meaning crisis society is going through. there was a time when science had immunity from consensus, and relied on facts. now it’s about who screams the loudest, like society.

    kids, smoke cigarettes. they’re not that bad after all!


  3. My problem with this study is that they did not have a real, separate “cannabis use only” group. The data is majorly flawed because of this. That damage that they found could be caused by a combination of use, and it would behoove the researchers to use three separate groups for the “smokers” category. Cannabis smoke only, tobacco only, and a combination of both. They should also specify the method of use for all groups; joint, pipe,bong,vape? Because I suspect the information would be more enlightening than a flawed study that doesn’t separate for specific use.

  4. Garbage “research” with a tiny sample size and a marijuana smoking group who “may have also smoked tobacco”. That’s not how you’re supposed to do science. The worst thing is that dozens of media outlets have picked this up. I hope you guys are proud of yourselves. The most drivel filled senseless article I’ve read all week… then again that’s pretty much all any of these “studies” are. Shameful work, folks. Be better. Get a real job, or at least do real research

    • Bingo!

      Talk about cherry picking tiny details to build the most alarmist headline possible.

      Barely even a mention that the “marijuana smokers” group was comprised mostly of folks who smoked both cannabis AND tobacco. No group of ONLY cannabis smokers analyzed? What kind of pseudo-scientific horses*** is this?

  5. I’m sure me taking 2 or 3 hits every evening is doing far more damage than people who smoke dozens of cigarettes a day.

    • what’s really troubling is that directly below this article is another health article about how much safer marijuana is to cigarettes…

  6. Smoke weed everyday

  7. whoever wrote this article should be ashamed.

  8. Bradley Mannion | November 17, 2022 at 6:50 am | Reply

    This is not new!!! This has been known for decades!!!

  9. Well, as it turns out, i am in a small percentage of pot smokers who has smoked over fifty years now BUT, i only smoked cigarettes for five years when i was around 20. At 65, i had an MIR on my chest and lungs and they found, and i quote, “five light spots” and i suspect that was from the cigarettes. Also, i decided to quit smoking one day about five years ago and over the course of the next two weeks, my blood pressure shot up incredibly high, to about 180/118!. So, i lit up and within 48 hours, my blood pressure went back to my usual 120/70…
    Yup, time for these scientists to put up or shut up about all their theories with no facts and actually do the science and collect the data, particularly from people like me!

  10. This article is incredibly misleading. The data used was from existing scans, meaning only smokers who had issues were included. It also appears that these are joint smokers, rather than users of bongs/water pipes/other smoking devices more common to marijuana usage that filters the smoke fairly significantly. The average usage was 1.85g/day of pot and 25 pack years for cigarettes, so they’re looking at specifically heavy users and have no data on casual use, which from my understanding is far more common for marijuana smokers.

    From the study:
    “This retrospective case-control study was performed with approval and waiver of informed consent from the local institutional review board. We included chest CT studies obtained prior to November 2020 at The Ottawa Hospital, a tertiary care center, and its affiliate hospitals. Patients were assigned to one of the following three groups: marijuana smokers, nonsmoker control patients, or tobacco-only smokers.

    Marijuana smokers.—Cases were identified by searching for the terms marijuana and cannabis in The Ottawa Hospital picture archiving and communications system, and results were filtered to include only those in which chest CT was performed. Charts were reviewed to assess the frequency and duration of marijuana use, as well as for concomitant tobacco use. A total of 56 marijuana smokers were identified with chest CT performed between October 2005 and July 2020. Patient ages were sorted into 5-year age blocks (15–19 years, 20–24 years, 25–30 years, etc), and the number of men and women in each age category was determined. Marijuana consumption was quantified using the conversion of 0.32 g of marijuana per joint, as described by Ridgeway et al (14).
    Our ability to quantify marijuana use was limited, with a daily amount specified in only 28 of 56 patients; average marijuana consumption among these patients was 1.85 g per day (range, 0.25–9.25 g per day). There were 50 of 56 marijuana-smokers who also smoked tobacco, with pack-year data specified in only 47 patients; average smoking history was 25 pack-years (range, 0–100 pack-years) (14).

    For tobacco-only smokers, average smoking history was 40 pack-years (range, 25–105 pack-years).”

  11. What a bunch of miss information. The researchers should be ashamed of this work. They obviously wanted to prove this before they even started. Bad Science!

  12. Really, after 70 years of Study “More research is needed” Duuuuuuuhhhh! How about the research on how it is WAY safer, less Lung cancer, less Suicide, less Mouth Cancer and way less heavy metal intake. It’s getting real old Guys.

    • An entire generation has been smoking weed since the 1960’s, over half a century, if weed causes any medical condition of any kind, where is the epidemic?

  13. An entire generation has been smoking weed since the 1960’s, over half a century, if weed causes any medical condition of any kind, where is the epidemic?

  14. I think the control groups were too small to prove anything. If I flip a coin and it lands on heads 6 out of 10 times doesn’t prove anything, much less a trend.

  15. You mean to tell me inhaling fine particulates that were created through burning organic matter (easiest way to create free radicals & carcinogens) is bad for your health? Who would have guessed.

    When I was younger I used cannabis recreationally (lost interest as I got older). I always did it using edibles. No one should be using any recreational substance through inhalation:
    1) It’s always going to be bad for you
    2) There are other ways of consuming the substance that aren’t inherently harmful

    All for people using drugs recreationally. I don’t support encouraging/enabling consumption methods that are inherently harmful in and of themselves (id ban the flower/vapes & legalize selling the oil/edibles)

  16. A paid article to try to scare general public against marijuana legalization?
    It is worse from alcohol (which is perfectly legal!) too?
    Also how about creating marijuana cigarettes which have filters (just like tobacco cigarettes) so that they are tested/compared on equal conditions?

    IMHO, overdose-safe drugs (like DMT, THC, LSD, Psilocybin etc) (which are actually safer than alcohol!) legally should/must be treated same as alcohol (which is really just another (similar) kind of drug)!
    IMHO, just like prohibition of alcohol had caused so much crime in the past (& that is why it was repealed many years later), prohibition of many similar drugs are causing so much crime today!
    We need to take lesson from history & end “War On Drugs”!!
    (Not to mention, (according to many medical research) drugs like DMT, THC, LSD, Psilocybin seem to be extremely promising against (major) depression & PTSD!)
    (& what benefits alcohol or tobacco have exactly (& yet they are legal)?)

  17. This is a repeat study. Tobacco smokers can smoke 5 f*@king packs a day. Try smoking to much Weed and you go to sleep. Goddam Eggheads need to find a cure for stupid instead.

  18. They dont mention the marijuana smokers also smoke cigarettes. If they could only find 33 tabbaco only smokers I GUARANTEE they didnt find 56 people who smoke marijuana and not tobbaco.

  19. “50 of the 56 marijuana smokers were also tabacco smokers” Straight from the study. So yeah, nonsense.

  20. After California legalized medical use in 1996, the UCLA school of cardiopulmonary health received an NIH grant to prove that smoking marijuana increased the risk of lung cancer. Seven years into the 10-year study involving thousands of people, the researchers announced that the data was so compelling that in the interest of public health they felt they needed to make public the result immediately.
    The study examined cancer rates among a control group, tobacco users, pot smokers, and people who smoked both pot and tobacco. The researchers urged tobacco-only smokers to start smoking pot.
    Among the four groups, cigarette smokers were found to have the highest cancer risk; smokers of both pot and tobacco were found to have a significantly lower risk than tobacco-only smokers.
    Next came the control group.
    Those who smoked only pot had a slightly lower risk than the non-smoking group.

    As to the present study, as written this is just click bait. What this study appears to have found is that the way people smoke cannabis — unfiltered joints and bongs — promotes emphysema. Perhaps, but as others have pointed out, many folks have been smoking for 50 years without a discernible public health emergency. So, really?

  21. Look into the butt of a cigarette. Whatever is making that filter brown is coating your lungs the sAme way. Ever clean out the stem of a bong? If you smoke weed, that brown, gummy THC buildup is in your lungs. It’s not hard to figure out both are bad for you. Weed smokers will defend marijuana at all costs. Cigarettes will kill you, and weed makes people stupid, paranoid, and lazy. Yes, it does.

  22. From the responses it appears many do not wish to face up to the fact that their pet habit of inhaling a dried plant to get there kicks outer life has potentail risks. It’s a no brainer. If one inhales anything beyond air, over continious years there is a higher chance that it will have a negative effect to ones health. Similar to tobacco’s effects. And then theres the negative effects to the brain. And research will eventually prove this, if not already.

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