Just days before Canada became the second country in the world to legalize recreational marijuana, a new study found that the drug can impair drivers for up to five hours after their last hit.
The study, which comes from researchers at McGill University in Montreal, found that drivers who smoked cannabis were able to complete simple tasks like braking and maintaining a steady speed on the road.
But when it came to more complex driving maneuvers, the study said, those high on weed were “significantly” more at risk for a crash.
“When we added distractions and (the) tasks required more attention and more focus and cognitive skills like divided attention … response time was much greater,” study co-author Dr. Tatiana Ogourtsova said, according to the Montreal Gazette. “We call them complex tasks, but they are things one has to do in everyday driving, which involves a lot of divided attention.
“I think the five hours maybe came as a surprise. We thought maybe the effects would not be as strong. But they were very significant.”
The study examined 45 people aged 18 to 24. Those involved in the study are “recreational cannabis users,” the study said, and were asked to complete different driving tasks before smoking marijuana — and then did the tests one hour after smoking, then three hours after and finally five hours after that last puff from a joint.
The tests proved smoking marijuana makes a driver less capable to cope with certain situations on the road, the study said.
However, the study also seemed to confirm the theory that marijuana can make a driver more cautious, if only for a short amount of time. Along with the driving tests, the study had people rate how they felt about their driving safety and driving ability before each section of the test.
“Performance was almost always significantly better without cannabis,” the study said. “The only exception was for vigilance at 1 hour after cannabis use: vigilance was higher at that time point than for the non-cannabis state. This finding is congruent with the findings of others who have reported an increase in vigilance or caution among participants who drove after cannabis use.”
Benjamin Hansen, economist at the University of Oregon, said that while it’s much safer to drive while sober, there is no clear link suggesting that marijuana can actually cause more motor vehicle accidents, according to LiveScience.
That could partly be because drivers high on marijuana are less likely to take risks, he said.
“They’ll drive slower, they’ll follow cars at greater distances,” he said, according to LiveScience. “They’ll take some actions that at least somewhat offset the fact that they’re impaired.”
Researchers noted that more studies would be needed on older drivers to determine what role, if any, age plays in response time.
A majority of Americans say that people driving while high on marijuana is “not much” or “somewhat” of a problem, according to a 2015 Gallup poll. Twenty-nine percent called it “very serious,” 39 percent said it was “somewhat” and another 31 percent said “not much.”
For comparison, 97 percent of people said alcohol is a “very serious” or “somewhat serious” issue for driving on the roads, according to Gallup. When it comes to prescription painkillers, another 83 percent said the same thing.
While Canada has fully legalized cannabis for adults aged 19 or older, nine states and Washington, D.C., have legalized recreational use of marijuana despite federal laws still classifying the drug as dangerous and illegal, as reported by Business Insider.
A 2017 poll from Yahoo News and Marist University found that a majority of American adults have tried marijuana in the past, with 22 percent saying they use the drug at least once or twice per year. Another 35 million say they use it at least once a month.
As more and more Americans begin to try marijuana, companies such as Hound Labs Inc. have started to work on creating a breathalyzer that can determine if a driver is currently high on the drug, according to USA Today.
THC, the main psychoactive component in marijuana, can remain in a person’s body for months under certain circumstances, so the breathalyzer works to see if any THC is in a person’s breath, USA Today reported. It would only be found two hours after smoking.