There are more deadly car crashes on unofficial weed holiday 4/20 than usual in the US

Scientists have found that there are more deadly road collisions than normal on April 20, the unofficial celebration for marijuana consumers in the US known as 4/20.

Researchers from the Universities of Toronto and British Columbia found that on average there were 7.1 fatal car crashes per hour after 4:20pm on April 20, compared to 6.4 during control periods.

They looked at 25 years of data – between 1992 and 2016 – to see how many vehicle crashes there were in the US where at least one person involved had died within a month of the accident.

They found there was a 12% increase in the relative risk of having a fatal collision after 4:20pm that day, with an even higher risk for younger drivers.

A man smokes a marijuana joint (Kirsty Wigglesworth/PA)

However, the scientists, who are experts in traffic injuries and hospital admissions, didn’t have much information on whether the drivers tested positive for marijuana use, partly as this is difficult to precisely test for as the drug stays in the system for so long.

In areas where marijuana use is legal, we know sales of the drug increase on that day. And driving under the influence of marijuana does increase risk of involvement in a traffic accident.

Car accidents in general do increase around holidays like Christmas – in part thanks to drinking, tiredness and more people on the roads.

In a 2003 study, researchers looking at 27 years’ worth of accident data on the day of the Super Bowl found a 41% increase in fatalities after the TV broadcast of the game had finished.

The study on fatal crashes on 4/20 was published in the journal JAMA Internal Medicine and can be read here.

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