Stephen Wallace, senior adviser for policy, research and education at SADD, stated "we hear from young people who believe that marijuana actually makes them a safer driver, that they concentrate harder, drive slower," Wallace says. “Those are all misconceptions”.
On the contrary, marijuana has serious harmful effects on the skills required to drive safely: alertness, the ability to concentrate and make good judgments, coordination, and the ability to react quickly. Marijuana use can make it difficult to judge distances and react to signals and sounds on the road. These effects can last up to 24 hours after smoking marijuana.
A roadside study of reckless drivers who were not impaired by alcohol showed that 45% tested positive for marijuana. Research conducted by the University of Auckland, New Zealand, proves the link between marijuana use and car accidents. The research found that habitual cannabis users were 9.5 times more likely to be involved in crashes .
Kelly, Darke and Ross show similar results, with laboratory studies examining the effects of cannabis on skills utilized while driving showing impairments in tracking, attention, reaction time, short-term memory, hand-eye coordination, vigilance, time and distance perception, and decision making and concentration. In their review of driving simulator studies, they conclude that there is evidence of impairments in cannabis-affected drivers' ability to control a vehicle in the areas of steering, headway control, speed variability, car following, reaction time and lane positioning.
"Teens are faced with potentially destructive decisions every day and don't always make the best ones," said Dave Melton, a driving safety expert with Liberty Mutual Insurance and managing director of global safety. "It's our job as mentors, parents, role models or friends to effectively communicate with them to ensure they are armed with the right information and aware of the dangers of marijuana and other substances, especially while driving."
1. "White House Drug Czar Launches Campaign to Stop Drugged Driving.” Office of National Drug Control Policy Press Release, November 2002.
2. Stephanie Blows, Rebecca Q. Ivers, Jennie Connor, Shanthi Ameratunga, Mark Woodward & Robyn Norton, "Marijuana Use and Car Crash Injury," Addiction, Vol 100, April 2005.
3. Kelly, Erin; Darke, Shane; Ross, Joanne (2004). "A review of drug use and driving: epidemiology, impairment, risk factors and risk perceptions". Drug and Alcohol Review 23 (3): 319–44. doi:10.1080/
Director of Ulster Prevention Council