Pot Use Doubles Car Crash Risk

By McCarton Ackerman 02/10/12

A new study shows that marijuana use dangerously impairs drivers' spatial awareness.

High drivers might unintentionally tailgate
and have trouble staying in lanes.
Photo via

Drivers who consume cannabis within three hours before driving are almost twice as likely to suffer a severe or fatal car accident as those not under the influence, according to a new study. The researchers—who published their findings online in the British Medical Journal—conducted a systematic review of nine studies on the subject of marijuana and driving accidents, with a total of almost 50,000 participants. According to Mark Asbridge, associate professor in the Department of Community Health and Epidemiology at Dalhousie University in Halifax, Nova Scotia, cannabis affects drivers' spatial location, potentially causing them to follow cars too closely or swerve in and out of lanes. This differs from the main effect alcohol has on drivers: slower reaction times. "People under the influence of cannabis often deny feeling impaired," says Asbridge. "There clearly is a lot of misconception about the extent to which cannabis impairs performance. People just don't believe it." The likelihood of marijuana use causing accidents is highest for drivers aged 35 and under.

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McCarton Ackerman is a freelance writer and editor living in Portland, Oregon. He has been a contributor for The Fix since October 2011, writing on a wide range of topics ranging from medical marijuana in Colorado to the world's sexiest drug smugglers. Follow him on Linkedin and Twitter.