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Study: 41% of Drivers Who Use Marijuana Drive Within 2 Hours

A new study highlights the poor usage habits of drivers who use marijuana.


A new study by the Insurance Institute For Highway Safety reveals some disturbing trends around marijuana use. The study revealed that Among the drivers who reported using marijuana, 41 percent reported using the drug two hours or less before driving.

The study looked at the behavior of drivers who self-report using marijuana and alcohol to find out how they separate their drug use from their driving. The resulting findings show that a large percentage of users don’t bother.

Related Story: Is Alcohol a Drug?

Interestingly, those who use substances that can impair driving don’t seem to view alcohol and marijuana equally when they consider whether to drive or not. Among the drivers who reported drinking alcohol, 28 percent reported drinking two hours or less before driving. 71% of all respondents reported that they had used alcohol in the past year, and 24% of respondents reported that they used marijuana.

What concerned IIHS researchers the most was the percentage of drivers who reported combining both marijuana use and alcohol use and then driving within two hours. 10% of all respondents reported using marijuana and alcohol together. Among these respondents who reported using the two drugs simultaneously, 33 percent reported drinking alcohol and consuming marijuana and then getting behind the wheel within two hours.

IIHS says that xperimental studies suggest using alcohol and marijuana simultaneously worsens driving performance more than either substance used separately. In an earlier IIHS study of emergency room patients there as the result of a motor vehicle crash showed an increased crash risk associated with marijuana when it was combined with alcohol.

“Alcohol impairment is associated with almost 30 percent of the fatalities on our roadways, and we have made very little progress to reduce this toll over the past three decades. Now we are adding another impairing substance to the mix,” IIHS President David Harkey said ahead of his presentation at the annual meeting of the Governors’ Highway Safety Association in Louisville, Kentucky. “Policymakers, law enforcement, safety professionals and others will need to work together and implement multiple solutions to save the thousands of lives cut short every year by impaired driving in the United States.”

The sum of the findings by IIHS can be viewed this way; If you pass 100 vehicles during a short trip, about three of those vehicles are being operated by a driver who self-reports using alcohol and marijuana together and then driving within two hours.

Approximately 11,000 people are killed in a motor vehicle mishap in America each year in which an impaired driver was involved. By contrast, Statista reports that a total of 1,051 victims were fatally injured during mass shootings in total in the United States between 1982 and July 4, 2022.

Image courtesy of IIHS.

John Goreham is a long-time New England Motor Press Association member and recovering engineer. John's interest in EVs goes back to 1990 when he designed the thermal control system for an EV battery as part of an academic team. After earning his mechanical engineering degree, John completed a marketing program at Northeastern University and worked with automotive component manufacturers, in the semiconductor industry, and in biotech. In addition to Torque News, John's work has appeared in print in dozens of American news outlets and he provides reviews to many vehicle shopping sites. You can follow John on TikTok @ToknCars, on Twitter, and view his credentials at Linkedin

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