 There are many ways people inhale marijuana. Most people smoke it, either in a bowl, pipe, joint, or bong. This is concerning, since in many ways smoke is smoke, and using a bong doesn't help in terms of the tar exposure, where there's fire, there's smoke, and where there's smoke there's inflammatory irritants. In fact, the regular smoking of cannabis is associated with the kind of airway inflammation you see in the lungs of cigarette smokers, which can result in prolonged respiratory symptoms, such as chronic coughing, excess sputum production, wheezing, and shortness of breath, as well as an increased incidence of bronchitis and other respiratory infection. In many ways, smoke is smoke, whether it's from burning plants in a forest fire or burning plants in a joint or cigarette. There are harmful byproducts of combustion, any combustion, like carbon monoxide. In fact, you get five times more carbon monoxide per puff in cannabis than tobacco, since pot smokers inhale more deeply and then hold the smoke in. Now you can avoid that completely by eating cannabis instead, but the slow erratic drug absorption doesn't give the same kind of immediate high. Inhaling cannabis vapor, however, could potentially offer the best of both worlds, giving the same kind of high in terms of subjective ratings compared to smoking it, but with significantly less carbon monoxide exposure. So similar effects with fewer toxic byproducts, though not necessarily all toxic byproducts. Both cannabis smoke and just vapor can evidently contain high concentrations of ammonia, and sometimes vapor can be even worse. So yeah, vapor has less tar, but may have more ammonia. This was with a direct heat vaporizer, the so-called blue meanie. Using a hot air vaporizer, like the volcano brand, results in ammonia levels in your bloodstream more comparable to smoking it. But the only reason we care about contaminants is we're trying to cut down on the inflammation. Does cannabis vapor produce fewer respiratory symptoms than smoke? According to this study, the first of its kind, yes. Now vaporizing doesn't help with dependence issues or impaired driving or brain damage among heavy adolescent users, but may improve cannabis drug safety by minimizing lung troubles. They conclude that regular users of joints, blunts, pipes, and water pipes might decrease respiratory symptoms by switching to a vaporizer. But this was just based on a snapshot-in-time internet survey asking people about their symptoms. You don't know for sure until you put it to the test. In a study funded by a pro-legalization group, they recognized that respiratory symptoms are a stumbling block in their efforts, so suggest inhaling cannabis vapor rather than smoke might minimize respiratory complaints. So they had 20 frequent cannabis smokers with respiratory symptoms switch over to using a vaporizer instead for a month, and those that didn't happen to fall ill with respiratory illness during that period experienced a significant improvement in their respiratory symptoms. But wait a second, 8 out of 20, 40% got a respiratory illness within a single month? That doesn't sound good, and indeed it's something they noted. Additionally, the self-reported improvements may have been tinged with bias as smokers might think such results might be good for the cause. This may have backfired, though, as there are calls in the medical literature to just legalize smokeless forms, or at least set it up so that smoked marijuana is more heavily taxed or something.