The illnesses materialized faster than anyone had anticipated. For years, the chemists who test marijuana concentrates had been warning about carcinogens and neurotoxins, about pesticides and solvents, about additives that turn harmful when heated in a vape pen. Almost everyone in the cannabis industry had a story about the dirty hash oil some company or another had pushed onto unsuspecting customers. But sales of vape pens kept growing, because consumers around the world loved getting high, discreetly, odorlessly, wherever they wanted. Vaping seemed like a juggernaut: a genuinely useful innovation in a hype-happy industry, a high-margin product in a business with increasingly thin margins, a piece of tech that lived up to Silicon Valley’s promise of improving people’s lives. Investors and lawmakers and activists all hoped legalization might chip away at the pot world’s seedier side without anyone getting poisoned.

That’s not how it worked out. On July 25, 2019, the Wisconsin Department of Health Services sent out a memo alerting health providers to eight cases of “Severe Pulmonary Disease Among Adolescents who Reported Vaping.” The Centers for Disease Control and Prevention opened an investigation, and by late August, there were several hundred possible cases of vaping-related lung injury in 25 states. Then people began to die.

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“There’s this old notion of ‘scared straight,’ and the data just don’t back that up as an effective strategy,” Robert MacCoun, a social psychologist and public-policy analyst at Stanford Law School, told me a few weeks after the workshop. American anti-drug programs for teenagers are particularly ineffective, he said, especially when compared with the more pragmatic advice given to kids in countries like the Netherlands, where they encourage youth to make decisions based on evidence. “We moralize to kids and exaggerate the harms, and then their own experience doesn’t match up,” he said. “They were hearing about the most extreme harms, but that’s not what they’re observing among their friends, so they go to the other extreme and dismiss all harms.”

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Robert MacCoun, the Stanford professor, had explained to me that the problem with saying vaping is safer than smoking is that once people see something as safer, more people start to do it, and they tend to do it more, negating a lot of the harm reduction.