A new Breathalyzer-style device can detect marijuana’s psychoactive ingredient, THC, for up to two hours post consumption, according to new research from the National Institute of Drug Abuse’s Intramural Research Program.

The SensAbues collection device (pictured above) works by trapping cannabinoids in a filter pad. The pads are then analyzed using mass spectrometry. This tool could be used by police officers and other officials when trying to determine if a driver is under the influence. As of right now, police officers take people suspected of being intoxicated to a medical facility where the suspect will have blood drawn and then analyzed. However, this method is not foolproof because the concentration of THC in the bloodstream steadily decreases while the person waits to have blood drawn. Thus, someone who is actually under the influence of marijuana while driving may show a negative test when they finally have their blood drawn and analyzed.

According to NIDA, the Intramural Research Program (IRP) recruited 13 frequent marijuana smokers (four or more times per week in the last three months) and 11 occasional marijuana smokers (less than two times per week in the same three month time period). The test subjects’ marijuana use was self-reported, so researchers were able to corroborate their stories by analyzing the concentration of THC in their urine, saliva, and blood.

In each study, the participants smoked a marijuana cigarette that contained nearly 7% THC and then they provided breath samples at regular intervals using the SensAbues collection device. According to NIDA, “Among the frequent smokers, 77% of breath samples collected at 1.4 hours tested positive; 54% were positive at 2.4 hours; and zero at 3 hours. Among the occasional users, 64% were positive at 1.5 hours, and none at 2 hours. The frequent smokers’ median THC breath concentration was 94.8 picograms (pg) per pad, and the occasional users’ was 61.0 pg per pad.”

Now the only question is, “How long until this device goes on the market?” According to NIDA, not so fast! Sarah Himes, a doctoral candidate in toxicology and the study’s leader, says the device still needs to be improved in order to increase sensitivity and detection times. NIDA and the IRP are currently planning studies in which participants will take a simulated driving test after consuming marijuana. The results will help to guide lawmakers when it comes to setting reasonable legal limits for THC breath concentrations.