Vast majority of cannabis users drive afterward, report says. These are the risks. (USA Today)
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A new study has found that more than 84% of cannabis users smoke, eat, drink or vape marijuana within eight hours of getting behind the wheel.
The AAA Foundation for Traffic Safety published a report that found 84.8% of cannabis users — 2,000 respondents from eight states — drove within eight hours of consumption, and 53% of these respondents drove within an hour or less of consumption.
As marijuana is legalized throughout the country − now recreationally legal in 24 states − researchers and law enforcement authorities are quickly looking to better understand how marijuana affects the body and brain. Even in the states where cannabis is medically and recreationally legal, it remains illegal for drivers to get behind the wheel after consuming the drug, yet there is no standard method for law enforcement agencies to identify or test marijuana impairment.
Here's what to know about the study's findings and just how much cannabis affects drivers.
Have cannabis-related motor vehicle accidents, deaths increased with legalization?
Data on motor vehicle accidents and deaths related to cannabis consumption varies, especially from state to state, but generally, legalization of cannabis has led to an increase, studies show.
Studying death certificates from 2009 to 2019, the University of Illinois Chicago found a 10% increase in motor vehicle deaths in four states where marijuana was legalized recreationally: Colorado, Oregon, Alaska and California.
Though marijuana-related motor vehicle accidents may be on the rise, the numbers hardly compare to accidents and deaths related to alcohol impairment.
Michael Greger, a founder of the American College of Lifestyle Medicine, wrote that while cannabis use may double or triple the risk of car crashes, alcohol multiples the risk six- to 15-fold.
Does cannabis affect driving performance differently from alcohol?
Yes, cannabis and alcohol can affect a driver's performance differently. Commonly, drivers under the influence of cannabis drive slower than those under the influence of alcohol, studies show.
A 2024 study published in the academic journal Traffic Injury Prevention found that 53 regular cannabis users who were under the influence spent more time at speeds "significantly" below the speed limit during a simulated driving test. In contrast, the study found that 18 of these users, under the influence of solely alcohol, spent 40% or more of the time above the speed limit.
Why is this the case? Alcohol impairment often leads to overconfidence, which may be the result of speeding, weaving through traffic and ignoring traffic signals, the Colorado Department of Transportation says. On the other hand, cannabis impairment may lead to anxiety and paranoia, which may make a driver more cautious and want to drive more slowly. Both types of impairment can affect judgment, coordination and reaction time, which increases the risk of a crash.
Is it OK to drive while under the influence of cannabis?
No. In all 50 states, even those where cannabis is legal, it is illegal to drive under the influence.
