Using marijuana can impair your judgment, motor coordination, ability to concentrate, and slow your reaction time. Therefore, it can
impair your driving skills. Anytime the skills needed to drive safely are impaired, even slightly, the chances of having an auto crash increase.
Specifically, studies have found that marijuana use affects the driver’s concentration and ability to perceive time and distance. This may lead to poor speed control, drowsiness, distraction, and the inability to read road signs accurately.
The Chances of Crashing Increases
More than one research study has found a direct link between THC (the psychoactive chemical in marijuana) concentration in the blood and impaired driving skills.
An analysis of several studies has found that the risk of being involved in a motor vehicle crash significantly increases after using marijuana.
Another meta-analysis estimates that the risk of a crash that results in serious injury or death doubles after marijuana use.
In the 2015 “Traffic Safety Facts: Drug and Alcohol Crash Risk” report, the National Highway Traffic Safety Administration (NHTSA) notes that THC increased crash risk by 1.25 times. This figure took into account contributing factors such as alcohol use and testing procedures for intoxication, so it is actually lower than some contradictory reports.
Some studies also note that high-risk groups for car accidents are those most likely to use marijuana. Most notably, this is young men in their late teens and 20s. This could play a factor in some of the statistics as well.