--- description: April 20 is known as a popular "4/20" holiday for pot enthusiasts, but researchers argue that the festivities may have serious consequences. title: Fatal Car Crashes Happen More Often Than Usual on 4/20 image: https://static.time.com/v3/assets/bltea6093859af6183b/bltfbdd14d2e33d72ef/69892713fb4eac43a6895a69/gettyimages-173361208-copy.jpg?branch=production&width=3840&quality=75&auto=webp&crop=16:9 ---  * [Health](/section/health/) ## Health Update your preferences in [Account Settings](/account/preferences/) Close * [Public Health](/tag/public-health/) ## Public Health Update your preferences in [Account Settings](/account/preferences/) Close # Fatal Car Crashes Happen More Often Than Usual on 4/20, Study Finds ## Video: The Real Reason We Associate 420 With Weed [Watch (HLS stream): The Real Reason We Associate 420 With Weed](https://cdn.jwplayer.com/manifests/HRGpsfdl.m3u8) (1:10)  _Published 2017-04-20. Both marijuana smokers and non-smokers recognize April 20 or 4/20 as a national holiday for cannabis culture, but few actually know how the date got chosen._ by [Alexandra Sifferlin](/author/alexandra-sifferlin/) ## Alexandra Sifferlin Update your preferences in [Account Settings](/account/preferences/) Close Feb 12, 2018 4:00 PM CUT  Cannabis leaves. Domain:Eukarya, Phylum:Magnoliophyta, Class:Magnoliopsida, Order:Rosales, Family:Cannabaceae. Cannabis leaves. Domain:Eukarya, Phylum:Magnoliophyta, Class:Magnoliopsida, Order:Rosales, Family:Cannabaceae.Getty Images by [Alexandra Sifferlin](/author/alexandra-sifferlin/) ## Alexandra Sifferlin Update your preferences in [Account Settings](/account/preferences/) Close Feb 12, 2018 4:00 PM CUT April 20 is known as a popular “4/20” holiday for marijuana enthusiasts, but researchers argue that the festivities may have serious consequences, including an increased risk of fatal traffic crashes. In a [research letter](http://jamanetwork.com/journals/jamainternalmedicine/fullarticle/10.1001/jamainternmed.2017.8298 "undefined") published Monday in the journal [_JAMA Internal Medicine_](https://jamanetwork.com/journals/jamainternalmedicine "undefined"), Canadian researchers looked at 25 years of data on fatal crashes in the U.S. They also compared the number of drivers involved in fatal crashes from 4:20 p.m. to midnight on April 20, and compared it to the same time frame one week earlier and a week later. The authors found that the risk of a fatal crash was 12% higher on April 20\. Among drivers under age 21, the risk was 38% higher. “The simplest interpretation of our findings is that more drivers are impaired by cannabis on 4/20 and these drivers contribute to fatal crashes,” study author Dr. John Staples, a clinical assistant professor of medicine and scientist at the University of British Columbia’s Centre for Health Evaluation and Outcome Sciences, told TIME. “But the underlying explanation may be more complicated.” **Read more:** [More Americans Want to Legalize Marijuana Than Ever Before](http://time.com/5090018/americans-support-legalizing-marijuana/ "undefined") Staples said there are other factors that could increase the risk of dangerous car accidents. For example, people might be drinking or doing other drugs in addition to marijuana. Still, the researchers note that their findings equal 142 additional deaths over the 25-year study timeline. “No matter where people live, I’d like them to know that impairment with drugs and alcohol increases the risk of crash,” Staples said. “Keep yourself and everyone else safe: Don’t drive high.” Keeping people who smoke marijuana safe on the streets is a more complicated matter than it seems, and it’s not just the fact that almost 40 states have now legalized marijuana for medical or recreational use. Proving that someone is actually driving while high is difficult. Not every state has an official threshold for what amount of detectable marijuana means a person is actually high. With alcohol, it’s straightforward: the more you drink, the drunker you get, and the higher your blood-alcohol content. But pot is different. When people smoke, THC spreads through the blood and is absorbed into tissues and the brain. But the amount of THC in a person’s body does not indicate whether a person is impaired. In states where some marijuana use is legal, law enforcement officials have to determine whether a person is impaired, and not just that they have marijuana in their system. “More research into cannabis intoxication, driving performance, and crash risk will help researchers and policymakers develop better impairment standards,” Staples said, adding that he thinks 4/20 event organizers should make transportation a part of their event planning and that doctors should talk to people about impaired driving not just when it comes to alcohol, but marijuana, too. ```json [{"@context":"https://schema.org","@type":"NewsArticle","@id":"https://time.com/5143828/420-april-20-marijuana-day-car-crashes/","mainEntityOfPage":{"@type":"WebPage","@id":"https://time.com/5143828/420-april-20-marijuana-day-car-crashes/"},"headline":"Fatal Car Crashes Happen More Often Than Usual on 4/20, Study Finds","datePublished":"2018-02-12T16:00:55.000Z","dateModified":"2026-02-23T19:14:21.480Z","description":"\"Keep yourself and everyone else safe: Don't drive high\"","url":"https://time.com/5143828/420-april-20-marijuana-day-car-crashes/","keywords":["Public Health","Marijuana","onetime","healthytime"],"thumbnailUrl":"https://static.time.com/v3/assets/bltea6093859af6183b/bltfbdd14d2e33d72ef/69892713fb4eac43a6895a69/gettyimages-173361208-copy.jpg?branch=production&width=1200&quality=75&auto=webp&crop=1200:675&height=675","author":[{"@type":"Person","name":"Alexandra Sifferlin","jobTitle":null,"url":"https://time.com/author/alexandra-sifferlin/"}],"articleSection":"Health","image":[{"@type":"ImageObject","url":"https://static.time.com/v3/assets/bltea6093859af6183b/bltfbdd14d2e33d72ef/69892713fb4eac43a6895a69/gettyimages-173361208-copy.jpg?branch=production&width=1200&quality=75&auto=webp&crop=1200:675&height=675","width":1200,"height":675,"headline":"Multiple sized marijuana leaves","caption":"Multiple sized marijuana leaves","creditText":"Getty Images","representativeOfPage":true}],"publisher":{"@type":"Organization","name":"Time","url":"https://time.com/","logo":{"@type":"ImageObject","url":"https://time.com/images/logo.png","width":528,"height":156},"foundingDate":"March 3, 1923","sameAs":["https://www.facebook.com/time","https://www.instagram.com/time/?hl=en","https://twitter.com/time","https://www.pinterest.com/timemagazine"]}},{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/section/health/","name":"Health"}},{"@type":"ListItem","position":2,"item":{"@id":"/tag/public-health/","name":"Public Health"}},{"@type":"ListItem","position":3,"item":{"@id":"https://time.com/5143828/420-april-20-marijuana-day-car-crashes/","name":"Fatal Car Crashes Happen More Often Than Usual on 4/20, Study Finds"}}]},{"@context":"https://schema.org","@type":"VideoObject","name":"The Real Reason We Associate 420 With Weed","description":"Both marijuana smokers and non-smokers recognize April 20 or 4/20 as a national holiday for cannabis culture, but few actually know how the date got chosen.","thumbnailUrl":"https://cdn.jwplayer.com/v2/media/HRGpsfdl/poster.jpg?width=720","uploadDate":"2017-04-20T16:15:37.000Z","contentUrl":"https://cdn.jwplayer.com/manifests/HRGpsfdl.m3u8","embedUrl":"https://time.com/5143828/420-april-20-marijuana-day-car-crashes/","duration":"PT1M10S","potentialAction":{"@type":"SeekToAction","target":"https://time.com/5143828/420-april-20-marijuana-day-car-crashes/?jw_start={seek_to_second_number}","startOffset-input":"required name=seek_to_second_number"}}] ```