Researchers at Washington State University are working on a new breath test that can determine if someone is stoned while driving.
Drivers under the influence of marijuana have been a concern among many since recreational use of the herb became legal two years ago.
One-fourth of blood samples taken from drivers in 2013 tested positive for pot, according to The News Tribune.
The new test involves measuring impairment with blood samples, which aren't used in current preliminary breath tests done by law enforcement officers to find out a driver's blood alcohol content. Patrol officers who suspect a driver is high also don't have immediate access to test results for THC, the psychoactive component of marijuana, in a driver's blood.
Herbert Hill, a chemistry professor at WSU and member of the team, said changes can be made to the technology currently used by airport security and customs agents for detecting drugs and explosives, and should be re-purposed to test breath for THC.
The hand-held device being developed at the university is able to identify THC in someone's breath thanks to a technique called ion mobility spectrometry. Five nanograms of active THC per milliliter of blood is the current legal limit for determining if a driver is impaired.
Hill said the test will initially only be able to tell officers that some active THC is present in a driver, and that it won't be able to determine exactly how much, The News Tribune reported.
However, officers will find the test helpful when deciding if they should arrest a suspected impaired driver. Law enforcement agencies would still have to have follow-up test results for evidence in court.
"We believe at least initially that it would lower the false positives that an officer would have." Hill said. "They would have a higher level of confidence in making an arrest."
The research has had positive reception among several lawmakers and law enforcement agencies.
Sen. Adam Kline (D-Seattle) said WSU will be the "forefront...of supplying this kind of science and the technology that's based on it to police all over the country."
Bob Calkins, a spokesman for the Washington State Patrol, said the agency is open to "anything that will help us get impaired drivers off the road," while adding that the technology should be fully developed before being used on the field.
Hill said the goal for his research team is to finish tests for the prototype marijuana breath test this year and begin human breath tests between January and June of 2015. The team will then run field tests for the device.
