Since cannabis has been part of civilization, people have consumed its flowers by smoking it. Today, even though cannabis can be consumed in different ways, smoking remains the primary method.
90.1% of adult users who consume cannabis are most likely to smoke it. In contrast, according to a 2020 survey by US Centers for Disease Control (CDC) and published in the journal Drug and Alcohol Dependence, the remaining respondents consume it through vaping, dabbing, or edibles.
Historically, health concerns around cannabis use have typically focused on its psychoactive effects. Therefore, cannabis use on respiratory health has received less attention.But as cannabis use becomes more widespread year after year, it is necessary to assess the effects of smoking cannabis on the lungs in the long term and whether it has the same effects as smoking cigarettes.
Although cannabis is the world’s most widely-used illicit drug, there is little research into its effects on respiratory health. Part of the reason is that it is challenging to study the long-term effects of an illegal substance. Also, the illegal status of cannabis makes it difficult to obtain reliable data on cannabis use and its effects. Self-reports of cannabis
consumption may be inaccurate due to the fear of legal consequences. Furthermore, as most cannabis users also smoke tobacco, the results of cannabis on the respiratory system may be obscured by those of tobacco.
But even if cannabis use is reported honestly, quantifying cannabis consumption can be tricky because there is no standardization of supply and significant variations in strengths and amounts of cannabis. Although most studies on the impact of cannabis smoke on the lungs quantify exposure to cannabis smoke as ‘joint-years,’ whereby one joint-year is equivalent to one joint smoked daily for a year, it can be smoked in different ways – bongs and pipes, and joints.
These other methods of smoking cannabis may influence the quantity and composition of smoke inhaled. According to a scientific article published in the BMJ Journal, smoking cannabis entails a two-thirds larger puff volume than smoking tobacco. The combustion products from a joint are retained much higher than in a cigarette.
When any substance is burned and inhaled, it creates an inflammatory response in the airways and lungs. Smoking cannabis can cause coughing, wheezing, and chest tightness.
The American Lung Association explains that the health effects of cannabis on the lungs are primarily determined by how it is consumed. Cannabis combustion contains many toxins, irritants, and carcinogens present in tobacco smoke.
But what is most interesting is how the impact of a cannabis puff differs from a cigarette puff on our lungs. Cannabis smokers usually inhale more deeply and hold their breath longer than cigarette smokers, which leads to greater exposure to tar.
Although cannabis and tobacco are two different substances, smoking cannabis can have similar effects on the lungs in the long term. Like cigarette smokers, cannabis smokers are also at greater risk of chest colds, bronchitis, and lung infections. A 2021 study published in the American Journal of Respiratory and Critical Care Medicine has shown that cannabis leads to lung damage but is different from that caused by tobacco.
The study documented cannabis use and measured lung function throughout more than 1000 individuals. Although the effects of cannabis were harmful, the pattern of lung function changes was not the same. Researchers found that prolonged cannabis use led to over-inflated lungs and increased the resistance to airflow to a greater extent than tobacco. They also found that cannabis use may also impair the ability of the lungs to extract oxygen from the breath. Researchers said this is a known consequence of smoking tobacco but wasn’t yet demonstrated with cannabis.
However, a 2012 study published in the Journal of the American Medical Association suggests that low to moderate use of cannabis is less harmful to users’ lungs than exposure to tobacco. In this study, researchers of the University of California, San Francisco, analyzed the relationship between current and lifetime exposure to cannabis and pulmonary function.
They measured airflow rate, defined as the speed at which a person can blow out air, and lung volume, which is the amount of air a person can hold, typically about six liters of air for an adult male. They found out that the more you use tobacco, the more loss you have with air flow rate and lung volume indicators, while airflow rate increased rather than decreased with increased exposure to cannabis up to a certain level. Researchers concluded that tobacco users typically smoke ten to 20 cigarettes per day and cannabis users, on average, smoke two to three times a month. Hence, the typical exposure to cannabis is much lower than to tobacco.
However, the study didn’t consider heavy cannabis users who can smoke many joints per day and that such a habit can have harmful effects on their lungs.A study published in the British Journal of General Practice in 2015 looked at 500 individuals who self-reported respiratory symptoms by using a questionnaire and measuring their lung function by spirometry.
The study read that cannabis use (predominantly use of resin cannabis smoked with tobacco) was associated with more significant reporting of respiratory symptoms. “The slightly increased presence of cough, wheeze, and sputum production are more likely in cannabis smokers. In addition, it was also associated with objective evidence of chronic obstructive pulmonary disease (COPD),” the study read. Researchers suggested that the adverse effect of cannabis is likely to be attributable to the tobacco included in the cannabis joint.
However, they also claimed that even after this additional tobacco smoked with cannabis was taken into account, the effects of cannabis on increased respiratory symptoms and increased prevalence of spirometric COPD were still apparent. Researchers concluded that there is clear evidence that cannabis has no marginal effects on respiratory health that are additional to the impact of the tobacco it is smoked with.Although scientific literature wasn’t unanimous on the effects of cannabis on the lungs, in the beginning, most recent reports have shown that cannabis may harm our lungs.
Also, assessing whether cannabis smoke can cause lung cancer can be problematic. Cannabis smoking, like tobacco smoking, may be associated with an increased risk of lung cancer. However, a 2006 study showed no such association even among long-term and heavy users.
Researchers explained that heavy habitual use had produced an accelerated, malignant change in lung tissue. Cannabis smoke contains several known carcinogens. It deposits four times as much tar in the lung as smoking a similar quantity of cigarettes, and cannabis joints are not filtered and are more loosely packed than cigarettes, so more particles are delivered to the lungs than tobacco.
However, the researchers found no increased risk of lung cancer from cannabis smokers compared with controls, although they did find a 20-fold increased risk of lung cancer among those who smoked two or more packs of cigarettes a day.Other studies that have looked for a definitive answer have found evidence that ties cannabis to lung cancer. In contrast, other data show little to no connection.