According to a twenty year study, smoking marijuana once a week or a little more apparently does not harm the lungs or do the damage that regular cigarette tobacco does. These results come from the longest and largest study on the health effects of marijuana. There is no data on people smoke marijuana on a heavier basis, which would be two or more joints a day for many years. There is some indication that doing it that often may decrease lung function but there were not enough heavy users in the study group to form any firm conclusions. The researchers who did the study do urge moderation and caution when smoking marijuana.
The researchers are not sure why because marijuana and cigarette tobacco both contain some of the same toxic chemicals. One reason that marijuana might not cause the damage and harm lung function like cigarette tobacco is that there is a chemical in marijuana that is not in cigarette tobacco. That chemical is called THC, which causes the “high” that people get when they smoke marijuana.
This chemical may counteract some of the effects of the irritating chemicals in the drug and also helps t fight inflammation. In addition, it could also be because when a person smokes marijuana they breathe in deeply when smoking a joint which might help to strengthen their lung tissues.
During the study, the researchers did not focus on the fact that both marijuana and cigarette tobacco users can develop coughs and throat irritations and the studies also did not examine lung cancer.