Steve Hoffman, the chairman of the Cannabis Control Commission (CCC), said he is concerned that a four-month ban on vaping devices imposed by Gov. Charlie Baker on Tuesday could negatively impact patients who use vaping devices to ingest marijuana medicinally.

“I respect the governor’s decision. I felt like he had to take action, and I respect that he had to take action,” Hoffman said during an interview with Boston Public Radio on Thursday. “From my perspective, I’m very concerned about patients that have used vaping as their preferred or only delivery system to get marijuana to help with their health concerns.”

Hoffman said that while there is no scientific consensus on whether vaping is a more effective way of ingesting THC, many consumers throughout the state have a strong preference of using vapes, and may not be comfortable inhaling THC or eating it in an edible product.

“I can’t prove that vaping is the most effective way for patients to get their medicine, but certainly a lot of patients feel that way,” Hoffman said.

Hoffman said that the CCC was aware of the governor’s plan to impose the ban, and understands why Baker took such drastic action. He does, however, worry that the ban will not only impact medical patients, but could encourage people to buy vaping devices on the black market, where there is no way to ensure the product is safe.

Read more: State Cannabis Regulator Says She Is Concerned Vaping Ban Will Push People To The Black Market

“I’m not criticizing his decision, but there are some things that I’m worried about,” Hoffman said. “One is more people going to the black market.”

Once more information about what is behind a recent outbreak of lung disease among users of vaping devices surfaces, Hoffman hopes that the CCC can work with Baker to determine what actions will be necessary for the comfort and safety of marijuana users.

“There is, unfortunately, not enough certainty in terms of what’s causing this, and as soon as we get that, certainty we’ll take whatever appropriate steps are necessary,” Hoffman said. “In the interim, we’re just cooperating with the governor’s order.”