Back in 2007, the British National Health Service (NHS) published an article with the headline “Smoking Cannabis ‘worse than tobacco’”. This conclusion came from a study* by Sarah Aldington et al. which took place at the Medical Research Institute of New Zealand in Wellington. It was published in Thorax in December 2007 and claimed that weed smokers had more damage to their airways in the lungs. As a result, it increased the likelihood of symptoms such as chest tightness, wheezing, and coughing.
The researchers based their findings on 339 adults and concluded that smoking one joint was as harmful to the lungs as smoking five tobacco cigarettes. This piece of research has been cited countless times by anti-marijuana campaigners as ‘proof’ that the herb is even more deadly than tobacco.
However, there was a myriad of limitations to the study which was acknowledged by the authors. For example:
- Although the volunteers were selected randomly, the sample did not contain enough cannabis smokers. The study also involved the recruitment of people via advertising which increased the risk of selection bias by attracting individuals who were especially concerned about respiratory health.
- A lot of cannabis users were ineligible for the study because they also abused other drugs.
- The study relied on people accurately remembering their tobacco and cannabis smoking history.
- As the study was exploratory and assessed various pulmonary structure, function, and symptoms, it did not correct for statistical tests. Therefore, it is possible that the ensuing associations were down to chance instead of a difference in the population.
Despite these limitations, the study has been championed as a true reflection of marijuana’s harmful effects. In recent years, a significant number of research studies have found that the damage caused to the lungs by cannabis smoking is significantly less than what tobacco users endure.
Cannabis & Tobacco’s Effect on the Lungs – The Truth
What’s especially odd about the 2007 study gaining such international attention is that there was a study predating it which came to the opposite conclusion. Given the anti-weed opinions that prevailed at the time, it probably shouldn’t come as a surprise that the results of the 2006 study* by Donald Tashkin of the David Geffen School of Medicine at UCLA were effectively ignored.
The study looked at over 2,000 people divided into three groups:
- Those who had lung cancer.
- Those who had cancer in the neck or head regions.
- Those who did not have cancer.
According to the study, which focused on people under the age of 60, 70% of patients with head/neck cancer, and 80% of those with lung cancer, had smoked tobacco. Less than half the patients with both types of cancer used marijuana. More pertinently, those who smoked 2+ packs of cigarettes a day were 20 times more likely to develop lung cancer. In contrast, even heavy marijuana use did not noticeably increase the risk of cancer. In fact, those who had smoked 22,000+ marijuana joints in their life did not suffer from a heightened risk.
At the time, Tashkin was shocked at the findings, which went against what his team had expected. He noted that previous studies had found that cannabis tar contained 50% more concentrations of chemicals linked to lung cancer than tobacco cigarettes, and smoking a weed cigarette deposited four times the tar in the lungs than an equivalent amount of tobacco. Tashkin surmised that the THC in weed could encourage aging cells to die quicker, reducing the risk of being subjected to a cancerous transformation.
In a 2009 study* by Liang et al., published in the Cancer Prevention Research journal, the research team found that cigarette smokers and alcohol drinkers were at greater than average risk of getting neck and head tumors. In contrast, moderate weed use was associated with reduced risk!
A 2012 study* by Mark Pletcher et al., published in the Journal of American Medical Association (JAMA), collected data over a spell of 20 years on 5,000 adults in four cities. The study was a joint venture involving the University of Alabama at Birmingham and UCSF. The team measured the air flow rate (the speed at which you can blow out air) and lung volume (the amount of air you are capable of holding). For the record, an adult male has a lung volume of six liters on average.
The study concluded that low to moderate use of weed in the long term is less harmful than exposure to tobacco. This is despite the fact that both substances contain a significant number of the same components. Although the team found that increased exposure to tobacco smoking resulted in a consistent loss of lung function, marijuana exposure did not have the same deleterious effects. In fact, airflow rate increased when people were exposed to marijuana up to a certain level.
Is Marijuana Use Effectively Harmless Then?
Unfortunately, no. One thing that all of these studies had in common was that low to moderate marijuana use did not harm your lungs nearly as much as the same level of tobacco use. In some studies, it had no significant negative impact at all. The same cannot be said for consistently heavy marijuana use.
When you breathe in, air is pulled down your throat into a series of airways that become narrower the further you travel. Ultimately, the air ends up in the alveolar ducts where your lungs exchange oxygen for toxic CO2. There are hundreds of millions of alveoli, and they work together to push oxygen into your bloodstream and pull out carbon dioxide which is exhaled.
There is no escaping the fact that, when you inhale weed smoke, you are inhaling harmful chemicals. Even the positive studies mentioned above found that smoke from combusted marijuana contains a significant proportion of the carcinogens and tar compounds found in tobacco cigarettes. Crucially, combustion happens at a temperature of over 1,000 degrees Fahrenheit and the toxic by-products could result in respiratory symptoms, including bronchitis.
Final Thoughts on Cannabis vs. Tobacco Lung Damage
Practically every study published in the last decade has found that cannabis smoking is less harmful to your lungs than smoking tobacco cigarettes. While the former has little or no impact on the respiratory system when used in small amounts, the latter is extremely harmful and massively increases the risk of cancer, especially in the lungs and throat.
However, heavy long-term marijuana smoking also has a negative effect on your lungs. Although the process doesn’t damage your respiratory system to the same extent as tobacco cigarettes, it is likely to impact your lung capacity to some extent. On the plus side, Dr. Tashkin suggests that you can reverse the damage if you stop smoking cannabis.
If you make that decision, switching to vaping enables you to continue enjoying marijuana while experiencing far less damage to the lungs. In most cases, vaporizers operate at temperatures between 300 and 400 degrees Fahrenheit, which avoids combustion of the weed and significantly decreases the number of toxic by-products you consume. Cannabinoids are powerful antioxidants and are capable of protecting the cells in the lungs from carcinogen damage. If you don’t like vaping, why not try edibles instead?