Study: Marijuana May Be More Harmful To The Lungs Than Cigarettes

Marijuana smokers are more likely to experience airway inflammation and chronic lung diseases like emphysema than non-smokers and tobacco-only smokers, a new study suggests.

After tobacco, marijuana is the second-most commonly smoked substance. It is also one of the most abused psychoactive substances globally. Its use has significantly increased in the US, Canada, and several other countries, especially in regions where it is legalized.

According to the Centers for Disease Control and Prevention (CDC), 48.2 million people used this psychoactive substance at least once in 2019. The CDC also reported that in 2020, an estimated 12.5% of U.S. adults currently smoke cigarettes.

The American Lung Association revealed that smoking marijuana could injure the cell linings of the large airways. This could be the reason why smoking the substance often causes symptoms like phlegm production, chronic cough, wheezing, and acute bronchitis.

Other lung conditions, such as air pockets between the lungs, air bubbles inside the lungs, and air pockets between both lungs, have also been linked directly to marijuana use. However, heavy marijuana smokers are more likely to experience these symptoms.

Marijuana or cigarettes, which is more harmful to the lungs?

A study published by the Radiological Society of North America (RSNA) helps shed more light on this. Study author Giselle Revah, M.D., a cardiothoracic radiologist and assistant professor at the University of Ottawa said, “there are well-researched and established findings of cigarette smoking on the lungs. Marijuana we know very little about”.

To learn more about the effects of marijuana on the lungs, Dr. Revah and his colleagues evaluated the chest CT examinations in marijuana smokers, tobacco-only smokers, and non-smokers as the control group.

The scientists narrowed their research by comparing the results of these substances on airway changes, emphysema, coronary artery calcification, and gynecomastia. They found a higher rate of emphysema among marijuana smokers (75%) than non-smokers (5%). However, there wasn’t a large difference when compared with the results of tobacco-only smokers (67%). This indicates that both substances can pose a high risk of emphysema - a lung condition that damages the air sacs and causes shortness of breath.

They also found that a specific subtype of emphysema, known as paraseptal emphysema, affecting the outermost area of the lung, was more prevalent among marijuana smokers than the tobacco-only group.

The scientists compared the rates of mucoid impaction, bronchial thickening, and bronchiectasis in the three groups. They realized that marijuana smokers are more liable to these diseases than the other two groups. They also identified that gynecomastia was prevalent among marijuana smokers.

However, the study had its limitations. There was difficulty in direct comparisons between marijuana and tobacco risks. Fifty of the fifty-six marijuana smokers also smoked tobacco. This fact presented a challenge in determining if the diseases seen in marijuana smokers were solely a result of marijuana, or if tobacco use was also a factor.

However, experts believe that the study points towards the direction that smoking marijuana isn’t risk-free, as many assume.

How is marijuana able to cause such damage?

Knowing the mechanism of marijuana’s action on the lungs will help in understanding how it can unleash its catastrophic activities on the organ. According to the American Lung Association, smoking marijuana breaks the lung's first line of defense against infection.

It attacks the cells responsible for removing dust and germs from the lungs, exposing the organ to foreign agents. It also causes lung mucus formation, increasing the risk of infection. The inability of the immune system to perform its defensive action in the lungs gives room to various respiratory ailments.

The publication in the Radiology journal explained why emphysema and airway inflammation is more prevalent among marijuana smokers. In general, marijuana is smoked unfiltered. This gives room for more smoke particles to reach the airways. Cigarettes are usually smoked using a filter.

To this effect, Dr. Revah said, “it has been suggested that smoking a marijuana joint deposits four times more particulates in the lung than an average tobacco cigarette.” He further said, “these particulates are likely airway irritants.”

Another reason could be that marijuana smokers usually inhale more smoke and hold their breath longer than tobacco smokers.

Final thoughts

Although experts couldn’t draw a firm conclusion from the Radiology journal publication, they believe that the study shows that marijuana isn’t totally risk-free and likely more harmful to the lungs than tobacco cigarettes. To further ascertain if smoking marijuana is more damaging to the lungs than cigarettes, more research needs to be done with a larger group of people and more data.