The NYPD knows that legal weed is coming, but it’s top enforcer has fears about underage smoking and dangerous marijuana grow houses.

“We have to make sure that we’re able to address people that are under 21 that are using marijuana to make sure there are sanctions for that and also to keep young people safe,” NYPD commissioner James O’Neill said Sunday on radio host John Catsimatidis’ AM 970 show, The Cats Roundtable.

Underage marijuana use stayed level in Colorado despite legalization for adults, according to a July 2018 state government report.

“I’m concerned about the gray and the black markets for marijuana,” O’Neill said. “We sent people from the NYPD out to Colorado and Washington and [California] to take a look at what’s happening out there.”

He added the city is working with Albany to work some concerns into pot legalization legislation.

“There’s a proposal out there that people are going to be able to grow their own marijuana in their houses,” he said. “We really really have to get this right.”

O’Neill pointed to the 2016 explosion of a marijuana grow house in the Bronx that killed a fire chief with debris responding to the house for a reported gas leak. The commissioner cited it as an example of something “that makes people unsafe.”

Last month, O’Neill complained of the need to retire marijuana-trained drug dogs, and the difficulty of detecting THC among stoned drivers.

“I’m concerned about driving while under the influence of marijuana,” he said again on Sunday. “Right now there is no instant test.”