Ask a Scientist: Does smoking marijuana cause as much harm to your lungs as smoking cigarettes?

By: Kylia Goodner

Marijuana is all over the news: being decriminalized, legalized, and sold in an ever-growing number of states around the country. But as its legal presence grows larger, it is important to consider the safety of smoking marijuana before you light up (legally, of course). 

Both tobacco and marijuana plants are made of carbon, which, if you remember back to your high school chemistry class, makes up all living organisms. So what happens when you burn carbon? Well a variety of harmful chemicals are released into the air, and these chemicals can hurt your lungs when you inhale them. But this is true for burning anything that was once living, including wood for a bonfire, or grilling a steak on a hot summer’s day. 

So if burning anything with carbon creates harmful chemicals, then why is tobacco smoke so bad for you? Well mainly, it is harmful because it is addictive, which means that people who smoke tobacco inhale a lot of smoke, usually in the form of cigarettes. Further, cigarette companies add an additional 600 chemicals to these cigarettes, compounding the harmful effect on your lungs. Typically, people are not sitting around a bonfire multiple times a day, every day, for years on end inhaling harmful smoke in the same way that people smoke cigarettes. 

But this response is supposed to be about marijuana, and its effect on your lungs. It’s been known since the 80s that marijuana and tobacco smoke contain many of the same chemicals. Therefore, you would think that smoking marijuana would have the same effect on your lungs as smoking cigarettes, but surprisingly this isn’t the case. 

A study looking at over 5,000 people over the course of 20 years found no association between smoking marijuana and the development of lung cancer. A separate study focusing on lung function in marijuana smokers found that there was no decrease in lung function up to 20 joint years (1 joint year = 365 joints). However, they did find a slight decrease in function for smokers above 20 joint years. On the other hand, long-term marijuana smoking has been found to increase cough, phlegm and wheeze. 

Unfortunately though, researching marijuana has been made difficult by laws restricting access to the plant and the chemicals it contains. Therefore, we don’t know much about its effects on other bodily functions, including other cancers and heart disease. We do know, however, that inhaling burned carbon often is not good for your overall health. So when marijuana is legalized in your state, be cautious, responsible, and consider safer ways of inhalation.