Many in the industry, as well as consumers, would like to see more states settle on a science-based cut-off limit for THC impairment. Police also rely on drug testing methods that examine blood, saliva, or urine; however, these can take days to yield a result. More importantly, these tests additionally can’t really tell whether a person has smoked half hour ago or eight days ago. While our ignition interlock devices are not designed to detect pot, blowing pot smoke into your device may damage the fuel cell technology, which is a program violation. All 50 states have ignition interlock laws, and each state has different requirements.

Breathalyzer-like devices that measure the main psychoactive chemical in cannabis — delta-9-tetrahydrocannabinol, or THC — have popped up in various stages of development. Whereas urine tests detect the presence of marijuana up to a month after impairment subsides, and blood tests up to three weeks, breath tests have the shortest detection window of up to just two or three hours after smoking. It’s an important distinction for law enforcement, who could in theory use a positive result as evidence of driving under the influence. One device, developed by Dr. Mike Lynn of Oakland-based Hound Labs, tests marijuana use within a specific timeframe, such as a driver smoking weed within the past three hours, which is allegedly when people are most likely to be impaired. According to the company’s website, THC levels become virtually undetectable in the breath after three hours.

Mike Lynn claimed that the test was extremely sensitive, so it didn’t matter whether you took a small puff of joint or ate a few edibles, the test would show a positive result because it measures the THC in picograms. Getting behind the wheel requires you to drive responsibly for your sake and for the sake of every person in traffic. You can get a DUI if you’ve consumed any substance that affects your driving, and that includes drugged driving.

The researchers at the University of Pittsburgh have also been researching a new breathalyzer that can detect the amount of THC in the breath. Their findings are presented in Science Daily and the review goes over how the breathalyzer is made. This device uses carbon nanotubes which are 100,000 times smaller than human hair and can detect THC levels similar to the gold standard of the mass spectrometry test. The professors, Alexander Star and Ervin Sejdic, used carbon nanotubes and machine learning to separate and detect the THC molecules in the breath.

The percentage of breath samples testing positive for THC declined steadily in both groups as time passed, but did so more rapidly among the occasional smokers . Among the frequent smokers, 77 percent of breath samples collected at 1.4 hours tested positive; 54 percent were positive at 2.4 hours; and zero at 3 hours. Among the occasional users, 64 percent were positive at 1.5 hours, and none at 2 hours.

However, this isn’t the same as a breathalyzer test, although some companies are getting closer to that goal. If you’ve been convicted of DUI and ordered to install an ignition interlock device in your vehicle, you may also be wondering if an ignition interlock device, or car breathalyzer, can detect marijuana. Current ignition interlock devices are made to detect alcohol and alcohol only. That being said, ALCOLOCK advises you to not operate your vehicle while impaired with marijuana or any other drug, including prescription drugs.

The privacy of responsible users won’t be compromised by a drug test that detects THC for days after use. According to a study by the National Institute on Drug Abuse, employees who tested positive for marijuana had 55% more industrial accidents, 85% more injuries and 75% greater absenteeism compared to those who tested negative. Drug testing for THC impairment, while necessary, up to now has been difficult.

In response to the first of these challenges, the IRP researchers are planning studies in which participants will take simulated driving tests after smoking marijuana. The results will the simpsons weed episode guide lawmakers in setting reasonable legal limits for drivers’ THC breath concentrations. “Our method allows a window of detection of only 1 to 2 hours after smoking,” Ms. Himes says.