Cannabis Science

What do weed smokers’ lungs look like?

what do weed smokers lungs look like

You might have heard what happens to the lungs of those who smoke cigarettes. Cigarette smokers tend to get lung cancer, lungs blacken with tar as well as an increased risk of certain lung diseases. As marijuana becomes legal in more and more places, many people are curious about it. People want information about weed’s effects and benefits. Naturally, there is tons of misinformation and so that’s why we turn to science to answer these questions. Research shows mixed results on how marijuana affects the lungs, so let’s examine further.

Feature Photo Source: Unsplash/Unsplash

What’s in marijuana smoke?

According to Healthline, marijuana smoke exposes you to toxins and carcinogens, which are cancer-causing chemicals.  There are two known carcinogens that are higher in marijuana smoke than in cigarette smoke. According to Healthline, “Marijuana smoke contains about 50 percent more benzopyrene and about 75 percent more benzanthracene than cigarette smoke.” In addition to that, according to National Institute on Drug Abuse, there are also more phenols, vinyl chlorides, nitrosamines, and reactive oxygen species in marijuana smoke than in cigarette smoke. 

Smoking marijuana, according to National Institute on Drug Abuse, leads to a deposit of four times more tar on the lungs. They explained that since people hold in marijuana smoke for a longer period of time and inhale more deeply, hence the tar can accumulate easier on the lungs. 

Can you get lung cancer from smoking weed?

It’s possible. As said before, some of the chemicals found in weed are cancer-causing. 

One study concluded that “heavy” cannabis smoking was significantly associated with more than a twofold risk of developing lung cancer over the 40-year follow-up period”. 

However, there doesn’t seem to be an accepted link between marijuana smoke and cancer. According to National Institute on Drug Abuse, “However, while a few small, uncontrolled studies have suggested that heavy, regular marijuana smoking could increase the risk for respiratory cancers, well-designed population studies have failed to find an increased risk of lung cancer associated with marijuana use.”

What’s interesting is that THC and CBD, found in marijuana smoke are being investigated for having anti-cancer properties. Maybe that’s what shielding marijuana users from lung cancer. More research needs to be conducted in this area. 

Does marijuana impair lung function?

According to Healthline, smoking weed can put people at risk for popcorn lung, chronic bronchitis, wheezing and chronic cough. These diseases could impair lung function. According to National Institue on Drug Abuse, “Marijuana smoking is associated with large airway inflammation, increased airway resistance, and lung hyperinflation, and those who smoke marijuana regularly report more symptoms of chronic bronchitis than those who do not smoke.”  The article also states that smoking weed can impair your respiratory system’s immune response and make you susceptible to infections. 

Evidence that marijuana doesn’t impair lung function 

However, according to a Harvard article, weed smokers can ‘breathe easy, literally. The article says, “…smoking marijuana in moderation may actually improve lung function, perhaps because inhaling gives the lungs and the chest muscles a bit of a workout.” 

Previously, we mentioned that those who use weed tend to inhale deeper and hold on to the smoke. In the study referenced by the Harvard article, that seems to be a good thing. The article said, “the deep, sucking inhalation may stretch lung tissue to expand lung volume. It may also strengthen the muscles of the chest wall, enabling pot users to inhale and exhale air more forcefully.”

The study which was published in The Journal of the American Medical Association (JAMA) in 2012, concluded that there wasn’t any evidence of adverse effects of marijuana use on pulmonary function. The researchers did note that this wasn’t ringing true for all levels of marijuana use. According to the study, “our findings do suggest an accelerated decline in pulmonary function with heavy use and a resulting need for caution and moderation when marijuana use is considered.” Harvard’s article about the study says that one blunt a day for seven years hasn’t shown to cause any problems with the lungs. Therefore, the risk of something happening would increase if someone were to smoke more than once a day it seems. 

What does this study mean

People who use weed for medical reasons or just generally in moderation should feel a sense of relief. However, Harvard’s article did point out some things about the study. First of all, it pointed out that the size of the blunts and the potency varied. There was also no real distinction in how marijuana was being smoked. The data that was used for the study (Coronary Artery Risk Development in Young Adults (CARDIA) didn’t specify if the participants used a joint, pipe, or a bong. Finally, as the article stated, “It would be a real exaggeration, though, to say this study proves that smoking marijuana is good for your lungs.”

How do I protect my lungs?

For some people, smoking may not be the best method of delivery. There are a variety of ways to use weed (besides vaping and smoking) to get the intended effects. For example, someone could use edibles to get high. One of the main differences is that the high will be delayed if you ingest weed rather than smoke it. According to Bustle, “Typically, it takes more time for the THC in edibles to hit the bloodstream compared to smoked marijuana, so giving your dose time to be fully metabolized before you try any more is key.”

With COVID-19 going around, which affects the respiratory system of many people who contract it, looking into other methods to use weed isn’t a bad idea in the meantime. 


There is clearly conflicting information about how smoking weed may affect your lungs. Marijuana smoke does have harmful chemicals in it. Some studies say that smoking weed can put you at risk for developing certain respiratory diseases. While others conclude that moderate use probably won’t impair lung function or give you lung cancer. The good news is, if you’re uncomfortable smoking a blunt, there are many other methods you can use.


About Trevann

Trevann is Stoner Rotation’s Jamaica-based lead writer for the Science section of our cannabis blog. She graduated with honors receiving her Bachelor of Science degree in Molecular Biology from the University of West Indies, Mona. For the last three years, she has covered some of the biggest questions around cannabis and health underpinned with research from supporting studies, medical journals and scholarly articles. Got something on your mind? You can reach her at [email protected].