TACOMA — Washington State University researchers say they’re close to having a portable breath test that police can use to detect if someone has recently consumed marijuana.

The News Tribune reports WSU professor Herbert Hill says his research team will soon begin its second round of testing of the marijuana breathalyzer in hopes of making the device available for police to use sometime next year.

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

Hill says the marijuana breath test is designed to test for THC, the psychoactive component that gives marijuana users a high, and not the metabolite that can stay in someone’s system for longer periods.