Put simply, the research used to claim that marijuana is worse for your lungs than tobacco clearly shows the exact opposite of that. One can simply read the results of the study to see that tobacco scored worse in most categories with regards to its effects on the lungs. The 5:1 ratio comes from the "airflow obstruction" category, in which marijuana did score worse. But that's just one of several categories. Furthermore, the study didn't even say marijuana was 5 times worse in that category. It said between 2.5 and 5 times worse, which dishonest reporters simply rounded up to 5 to get headlines.
If we're talking about the lungs, the two biggest concerns are emphysema and lung cancer. Tobacco scores far worse in both categories:
Emphysema was detected in only one of the cannabis smokers (1.3%), in 15 (16.3%) of the cigarette smokers, in 17 (18.9%) of the combination smokers, and in none of the non-smoking groups. [MedPageToday.com]With regards to lung cancer, the case for is even stronger. Conclusive evidence shows that marijuana does not cause lung cancer at all, and may even help prevent it.
While smoking marijuana is never good for the lungs, the active ingredient in pot may help fight lung cancer, new research shows.That's the research, now for the common sense. It should be easy to understand that tobacco users smoke more than marijuana users. That's just a fact, and it has everything to do with the relative harm of each. Even if marijuana were more harmful to the lungs, it still wouldn't matter at all, because hardly any marijuana users actually smoke enough to hurt their lungs. Most don’t even smoke every day. They also quit more easily, thus consuming a vastly smaller quantity in their lifetime. The two cannot even be compared for this reason.
Harvard University researchers have found that, in both laboratory and mouse studies, delta-tetrahydrocannabinol (THC) cuts tumor growth in half in common lung cancer while impeding the cancer's ability to spread. [Forbes]
One should never be surprised to find the anti-marijuana propaganda machine turning out wildly exaggerated scare stories about the dangers of pot. But this whole episode provides a startling depiction of how irresponsible and just plain wrong marijuana's critics always prove to be.
So, to recap: marijuana is more likely to cause "airflow obstruction," while tobacco is more likely to cause emphysema and lung cancer. You tell me which one is 5 times worse.