Charlie Baker, normally cautious, takes criticism over his ban of vaping products

“This was not an easy decision,” Governor Charlie Baker said of the four-month ban.Jessica Rinaldi/Globe Staff/Globe Staff

Tucked into a State House conference room last Friday, Governor Charlie Baker listened for close to an hour to doctors at the top of their fields, consuming a crash course on the dangers of vaping.

The exercise was classic Baker: Cautious and evidence-driven, he’s a technocrat who promotes the “blocking and tackling” of state government, rare to leap and especially without a long, long look.

And then, he leaped.

Days later, Baker issued a sweeping order to temporarily ban the sale of all vaping products, pushing Massachusetts beyond where any state has gone to address a nationwide explosion of vaping-related illnesses.

The four-month prohibition immediately shelved the state’s legal supply of electronic cigarettes — and for some small businesses, their lifeblood — stoking debate and legal threats over how far elected officials should go to confront a new and confounding public health problem.

It also pushed the famously temperate chief executive into unusual criticism: He is suddenly being called “radical,” and his decision “dangerous,” a policy wonk gone too far.

But how the governor ordered the country’s most extensive vaping crackdown is rooted in a familiar territory: A meeting, a fourth-floor conference room, and, in Charlie Baker cadence, a “fact pattern” that called for something bigger than what others had already embraced.

“This was not an easy decision,” Baker said in an interview Thursday. “But when you have a room full of medical experts saying that the national problem and the Massachusetts problem that’s associated with a debilitating illness — that is potentially fatal — is related to vaping, the more we talked about it, the more we felt to not do something like this would be a much more dangerous outcome.”

That room of medical experts arrived early Friday afternoon one floor above Baker’s office, after his administration asked more than a half-dozen doctors to the State House to discuss the outbreak of suspected vaping-related illnesses. The three dozen or so cases the state had identified at that point have since grown to 66, state officials said this week, including three confirmed cases that have been reported to federal officials.

According to Baker, the hour-long discussion was an “affirmative and unanimous confirmation” of vaping’s dangers, and a key part in his decision to order the ban. The group of addiction specialists, pulmonologists, and pediatricians warned, Baker said, that the problem would only escalate without action. And given the uncertainty around the cause of the outbreak — nicotine versus marijuana, or regulated versus black market — the focus, they said, shouldn’t be on a certain product, but on vaping itself.

“They made a pretty compelling case that this is not something you should screw around with,” Baker said. “I think just based on that fact pattern, [a complete ban] seemed to be the only option that was the appropriate one.”

Nonetheless, his decision left even those in the room surprised.

The seven medical professionals had each spent time Friday laying out to Baker what they knew, including descriptions of cases of once-healthy adolescents in the hospital struggling to breathe, attendees said.

Dr. Benjamin Raby, chief of the division of pulmonary medicine at Boston Children’s Hospital, took Baker through how the effect of e-cigarettes on people’s lungs can mimic that of traditional cigarettes, but how doctors had never before seen the type of acute, potentially fatal illnesses created by short-term exposure to vaping.

Dr. Sharon Levy, the director of the Adolescent Substance Use and Addiction Program at Children’s Hospital, described it juggling in recent years a sixfold increase in the number of calls it’s received, a spike largely driven by vaping.

“He said on a couple occasions, ‘I haven’t really heard this before,’ ” Levy said of Baker. “He was trying to get a sense of, ‘Is everybody seeing this?’ ”

Then, according to Raby, the pulmonologist, Baker turned the discussion to what recommendations they had. “Most everybody around the table, from the outset, thought that a ban was the most effective action,” Raby said.

But questions among the group remained, he said: If the state banned just one type of product, would that send a mixed message? And if you ban all products, then how could the state help prevent people from simply turning to cigarettes?

At that point, Baker, a former health insurance executive at Harvard Pilgrim Health Care, turned to his public health commissioner, Monica Bharel, about the state’s options, Raby said. (Officials this week have emphasized a state help line that could help connect smokers to free nicotine patches or gum.)

“It was a discussion in real time,” Raby said. “The impression I got, I don’t feel he was looking for us to come in to validate one thing or another. . . . And when we said [a ban] would be a very bold move, that it would be a real statement, he made it clear that really wasn’t the priority. The priority was, what was the most effective thing to do?”

When the meeting ended, Baker did not indicate how he was leaning, attendees said. But by Monday, Raby said, he was asked again to come to a meeting, this time with the Public Health Council. The panel, he was told, planned to formally approve a four-month ban on all vaping products Tuesday.

“We were quite surprised, not that it was too bold or inappropriate, but pleasantly surprised that appropriate action was taken,” said Raby.

“To be perfectly honest,” said Levy, also of Children’s Hospital, “we can’t even ban assault rifles. When he made his announcement, I thought, ‘Wow, that’s kind of stunning.’ ”

Other states have made sweeping announcements in the face of hundreds of vaping-related illnesses. But bans ordered in Rhode Island, New York, and Michigan target flavored products, not all vaping products. And while San Francisco became the first major city to prohibit all electronic cigarette sales, its policy doesn’t go into effect until next year.

Baker’s order — unveiled at a Tuesday afternoon press conference where he also declared a public health emergency — immediately sparked an outcry from within the state’s legal marijuana industry and vaping retailers, who criticized it as too heavy-handed. By Thursday, at least one shop owner said he is challenging the ban in court.

Baker, who has framed the ban as an effort to give officials time to identify the root causes of the outbreak, indicated he was confident it would withstand legal scrutiny. Plus, he said, to continue to allow shops to sell a product that could be potentially contributing to a “public health crisis didn’t make any sense.”

“We think 120 days to sort this out and figure out A) more information about what might be the root cause of this and B) what we could do from a regulatory point of view to deal with it going forward is a very defensible position,” he said.

“We chase facts,” Baker added, ticking through initiatives from addressing the state’s opioid crisis to the state’s pursuit of offshore wind, before again turning to that room of experts and that “fact pattern.”

“That’s the way we do business around here,” he said.