Puff test for pot use will be reality within a year, WSU researchers say

Joints for sale at Mr. Bill’s of Buckley, the first recreational marijuana store to open in Pierce County outside of Tacoma, are shown in September 2014.
Joints for sale at Mr. Bill’s of Buckley, the first recreational marijuana store to open in Pierce County outside of Tacoma, are shown in September 2014. Staff photographer

Researchers at Washington State University say they think they are about a year away from having a portable breath test that police can use to detect if someone has recently consumed marijuana.

Roadside breath tests already exist to detect whether drivers have consumed alcohol. But officers have no similar device to test drivers for marijuana use, said Herbert Hill, a WSU chemistry professor working on the project.

Hill said his research team has completed its first round of testing of the marijuana breathalyzer and has made some improvements. The team is about to start a second round of testing, and Hill said he hopes to make the device available for police to use in the field sometime next year.

“For it to be used to help the arresting officer make a decision I hope is about a year away,” Hill said Tuesday.

Hill updated state lawmakers on the breath test project at a Thursday (Oct. 22) meeting of the Senate Law & Justice Committee.

State Sen. Mike Padden, the committee chairman, said Tuesday that state officials are interested in any tools that could help officers more accurately determine whether they need to detain someone for impaired driving.

While police would still need to get a warrant and draw a person’s blood to see if they meet the legal definition of impairment under the state’s marijuana laws, a breath test could be a more reliable way to detect marijuana impairment than the field sobriety tests that officers use now, Padden said.

“This would be a more accurate test for them to determine whether someone is impaired, and combined with other evidence, whether they need to make an arrest,” said Padden, R-Spokane Valley.

Initiative 502, which voters approved in 2012 to legalize recreational marijuana use, said drivers are considered impaired if they test positive for at least 5 nanograms of delta-9 THC per milliliter of blood.

The marijuana breath test under development at WSU is designed to test for delta-9 THC, the psychoactive component of marijuana that causes someone to get high — not the metabolite that can stay in someone’s system for days or weeks, Hill said.

Hill said right now the test determines only whether delta-9 THC is present in someone’s system, and not what level is in their blood.

Out of 30 times the test was recently used on someone before and after they smoked marijuana, it accurately detected THC in the person’s system about half of the time, Hill said.

The test turned up only one false positive during the trials, Hill said.

He said that’s encouraging because researchers are continuing to refine the breath test and will only improve on those results. The research team has already made changes that will help make the test more accurate going forward, he said.

“We don’t want to accuse somebody of smoking marijuana when they didn’t,” Hill said.

Nicholas Lovrich, a WSU professor of political science who also teaches criminal justice courses, said the breath test could act as an important deterrent for people who may choose to drive after consuming marijuana.

He said that while research shows marijuana doesn’t affect a person’s driving nearly as much as alcohol, it still causes impairment that is dangerous, especially if used in combination with alcohol.

“It’s not about punishment, it’s about letting people know, ‘you’ll get caught,’ ” said Lovrich, who is working with Hill on the THC breath test. “People who assume that they’re a good driver when they’re high, it’s not true. All the research shows they’re not.”

“They need to know that they can get caught if they use and drive,” he said.