Jolie Lee

USA TODAY Network

Colorado, the first state with legal recreational marijuana, is rolling out public service announcements warning marijuana users about stoned driving.

The state Department of Transportation is airing three television ads as part of its "Drive High, Get a DUI" campaign.

The ads appear during shows that target men ages 21-34, the demographic that tends to have the highest number of DUIs, according to a CDOT release.

In one ad, a man finishes installing his TV on the wall, and a moment later the TV set falls off the wall. "Installing your TV while high is now legal," reads the text in the ad. "Driving to get a new one isn't."

Colorado started selling recreational marijuana on Jan. 1. The only other state that legalized recreational pot is Washington, which will start selling it this year. Nationwide, 20 states, plus the District of Columbia, have legalized medical marijuana.

"As Coloradans now have more access to marijuana, we want them to be aware that law enforcement is trained to identify impairment by all categories of drugs and alcohol," said Col. Scott Hernandez, chief of the Colorado State Patrol, in a statement.

The limit for marijuana in the blood is 5 nanograms of active THC per milliliter of blood, according to CDOT.

But it's not clear-cut how much marijuana that is exactly. Unlike blood-alcohol content, which generally correlates with weight and number of drinks, marijuana affects different people in different ways.

"One hit could put someone over the limit," said Emily Wilfong, CDOT spokeswoman, in an interview with USA TODAY Network.

She added that there is more than one way to consume marijuana. "For instance, edibles can take up to two hours before someone even starts to feel the effects."

The campaign aims to educate the public that driving high is still considered impaired driving, Wilfong said. A September CDOT survey of 770 Coloradans found 21% had driven a motor vehicle after consuming marijuana sometime within the past month.

There are still a lot of questions about whether the 5 nanogram limit is an accurate mark of impairment, said Mason Tvert, spokesman for the Marijuana Policy Project.

"Too much evidence suggests that it would result in people being unfairly convicted of a DUI when they're actually not impaired," Tvert said.

In Colorado, the state presumes impairment with a 5 nanogram THC-blood level, but the driver can rebut the charge that they were impaired, and a jury can still find them not guilty despite the test result, Tvert said.

In contrast, in Washington, a THC-blood level of 5 nanograms or more automatically means you are driving impaired under the law, Tvert said.

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