Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

There are many ways people inhale marijuana. Most people either smoke it in a bowl, pipe, joint, or bong. This is concerning, since in some 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 infections.

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 by-products,” though not necessarily all “toxic by-products.”

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 that 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 “[r]egular 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 “twenty 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 a respiratory illness during that period experienced a significant improvement in their respiratory symptoms.

But, wait a second, eight out of 20—40%—got a respiratory illness within just 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.

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