A Harvard University research team examined lung imaging to determine the association between cannabis consumption and health risks often attributed to tobacco smoke. The study published in Current Problems in Diagnostic Radiology found that cannabis smoking poses fewer pulmonary risks than tobacco smoking. In addition, the study indicated that cannabis smoke is not positively associated with emphysema.
The researchers compared chest CT scans of 285 study participants. Eighty-nine participants were non-smokers, 97 smoked tobacco, and 99 smoked cannabis. Although the researchers used propensity score matching, the cannabis user group (mean age 59) was younger than the smokers (mean age 62) and non-smokers (mean age 64). Sex distribution was similar across all groups.
The team used quantitative CT analysis to measure total lung volume (TLV) and observed that TLV was higher in tobacco users compared to non-smokers and cannabis consumers. Visual analysis suggested that 62% of smokers had emphysema, whereas 4% of cannabis users did not. More tobacco smokers (43%) had moderate to severe coronary artery calcifications compared to cannabis users (25%).
Data analysis revealed that tobacco smokers demonstrated more damage to their hearts and lungs than individuals who solely consume cannabis. Tobacco users were more likely to develop centrilobular emphysema and moderate or severe coronary artery calcifications. Overall, cannabis consumers are not as likely to develop emphysema or pulmonary hyperinflation.
A 2012 study conducted by the University of Alabama at Birmingham also found cannabis smoke was not as damaging as tobacco smoke. Other studies have also indicated less risk associated with cannabis smoking. More research is needed to examine the patterns of pulmonary and cardiovascular risks associated with both cannabis and tobacco use. Research studies should investigate the risks associated with various modes of cannabis consumption, including diverse smoking devices and vaporization.