With that caveat out of the way, on to the practical guidelines.

This is a complex question that—if cannabis is indeed to be treated as medicine—should be addressed with experts on an individual basis, to properly calibrate safety and dosing. But since most marijuana is still used outside of the doctoral setting, we have LRCUG. For people who are already smoking, the recommendation is to “choose other methods, such as vaporizers or edibles—but recognize that they also come with some risks.”

Good advice—it’s rare that any doctor would recommend burning any drug and inhaling its smoke over simply ingesting it. Smoking can complicate dosing, and it is frowned upon in hospitals. But most importantly, inhaling smoke irritates and inflames the respiratory tract, which can hypothetically lead to cancer, regardless of the source of smoke—whether it’s smoke from marijuana or tobacco, and probably even if you’re smoking pure kale or multivitamins. Inhaling wood smoke from a campfire can reduce lung function and cause chronic lung disease, if you spend enough time pulling it directly into your lungs. (Do you do that? Email me.)

The point, evolutionary biologists agree, is that humans evolved to breathe air. And there are other ways to get equally if not more medicated or recreationally mellowed. So, on to those.

Katie Martin / The Atlantic

First there is super-heated vapor. Despite Ben Affleck serving as a meandering cautionary tale of the emptiness of vaping anything, portable tobacco vapes have obviously become popular in recent years, growing to a $4.4 billion industry in the United States. This industry carries increasing political weight, with the tobacco industry lobbying to rescind regulations on vape products enacted under the Obama administration, and the Trump administration likely to acquiesce. The popularity of vaping devices among The Millennials, and the concerted efforts to grow that market share and foster nicotine addictions among young people, are an intensely problematic historical relapse.

Meanwhile marijuana smokers have been vaping since the dawn of time—if not in a portable capacity. I remember first meeting the enormous, iconic Volcano Performance Vaporizer about a decade ago. It’s a 10-pound, stainless-steel tabletop cone that costs $599 and shoots hot air through a disc filled with ground cannabis and up into a giant transparent balloon, which in my experience is then passed around at a party, and from which people take turns inhaling and becoming progressively less fun to talk with.

I remember thinking at the time that this “vapor-ing” idea seemed like a swell way to mitigate the risk of inhaling smoke, and I said so at the time, even though people didn’t really want to talk about that during the party.

The vape-related dangers that the Canadians note are related to the fact that, even though vaporizing weed is definitely better than smoking it if all other things are held equal, all other things are never held equal. Changing a route of administration changes people’s habits, and their whole perception of the drug. The idea that vaping mitigates the risk of smoking could make people more likely to intoxicate themselves, more often, et cetera. When that sort of usage becomes a problem socially, professionally—or in any of the other ways that relationships to mind-altering substances can become problematic—then vaping would indeed be unsafe.