A considerable proportion of people who smoke pot have rather blasé attitudes towards driving while high, with surveys showing many users are convinced the drug doesn’t impair their ability to drive safely.
Now, a new Canadian study suggests using pot before driving increases the risk of a crash even five hours after inhaling.
McGill University researchers found that performance in key areas such as reaction time decreased significantly, and that the effects lasted up to five hours after inhaling the equivalent of one typical joint.
Simple driving tasks were largely unaffected, but once the situation became even complicated with normal distractions, that’s when the wheels started coming off, according to the paper published in CMAJ Open Monday, two days before Canada’s prohibition on recreational marijuana is lifted.
The Canadian Automobile Association, whose polling has found that one in five millennials (18- to 34-year-olds) believe they can drive as well — or even better — stoned as they do sober, funded the research.
With the legalization of recreational weed, “young adults, who are already at risk of automobile crashes, may increase their use of cannabis, which may further increase the risk of crashes,” the authors write in CMAJ Open.
Until now, there’s been confusion over whether people can safely consume any amount of cannabis before driving.
While alcohol has been shown to impair a user more than cannabis, some studies have found cannabis can have various effects on driving, including increased breaking, more weaving within lanes and distorted time perception.
Less clear was how long any effects might last.