Driving after cannabis use: Perceptions of drivers during the transition to legalized non-medial cannabis in Canada

Author(s): Cristiano, Meister

Slidedeck Presentation:

2A Cristiano



The 2018 regulation and legalization of non-medical cannabis in Canada has raised a number of public health concerns, including driving after cannabis use (DACU). Past studies demonstrate that people’s perceptions of cannabis impairment often influence their decision to drive, particularly those who believe cannabis does not impair and choose to drive soon after use. Yet, legalization saw an increase in public education on the risks of cannabis use and cannabis-impaired driving (CID), which might have affected public perceptions. As such, it is necessary to examine perceptions of DACU to ensure policy and educational interventions remain relevant or are adapted where necessary in this changing context.


The objective of this study is to examine perceptions of cannabis use and driving, in relation to driver characteristics, from a sample of Canadian drivers who report using this substance. It is hoped these findings provide additional insights for policy makers, road and public safety practitioners, and other stakeholders addressing CID issues.


Data for this study are drawn from the National Cannabis Survey series led by Statistics Canada. Conducted quarterly beginning in early 2018, a sample of Canadians are surveyed on various questions pertaining to cannabis in general (e.g., use, types, sources) each cycle and on specific topics (e.g., driving) during specific cycles. Using descriptive statistics, we analyze the self-reported data for relationships between perceptions of DACU and different characteristics (e.g., age, sex, frequency of use, etc.). Regression models are used to conduct a deeper analysis of participant responses to when it is safe to DACU, including responses to ‘depends on the person’.


Analysis of the data is currently underway, yet preliminary findings indicate that those who believe it is safe to drive within three hours are more likely to be male, youth or young adults (15-24 years old), engage in daily or almost daily use, and use cannabis for only medical or for only non-medical purposes but not both. Logistic regression results suggest that those most likely to believe that it ‘depends on the person’ appear to be females, youth and young adults, and individuals who report combined medical and non-medical use. Additional findings are emerging.


Initial findings appear to indicate that certain characteristics of individuals (e.g., sex, age, methods of use, etc.) differ between those who perceive risks of cannabis use along a linear time line (i.e., hours after use) and those who perceive risks as dependent on biological factors (i.e., sex, weight, etc.). Given that multiple factors can play a role in cannabis impairment (e.g., time after use, method of consumption, chemical concentrations, etc.), the findings suggest some misperceptions and gaps in knowledge persist, but differ depending on individual characteristics. Study limitations are present, such as smaller sample sizes for particular characteristics (e.g., seniors), reducing some analyses.


The study findings could have important implications in terms of prevention and education of cannabis-impaired driving. Tools, activities, and resources for the public may need to be more nuanced in order to effectively target perceptions held by specific groups of people.