Driving and cannabis use: a questionnaire about knowledge and behaviors after the legalization of recreational cannabis in California

Background: Implemented in 2018, Proposition 64: The Adult Use of Marijuana Act legalized recreational cannabis use in California. This study aimed to assess driving-related knowledge, attitudes, and behaviors after the passage of Proposition 64. Methods: An initial questionnaire was completed by 15,208 participants demographically matched to the 2020 California census. A subset of 4,020 participants who currently use cannabis, 523 who formerly used cannabis, and 635 who never used cannabis completed a detailed mixed qualitative and quantitative questionnaire, including questions about driving which were selected for this sub-analysis. Chi-square analysis was utilized for descriptive analysis. For this study “cannabis” was defined as THC-containing products. Results: 62% of current cannabis users were aware that drivers and passengers cannot smoke or ingest cannabis in a moving vehicle, and 59% were aware that any container of cannabis inside a moving vehicle must be unopened and sealed. 74% knew that you could get a citation for driving under the influence of cannabis (DUIC). 64% of participants reported feeling safe to drive 3 h or less after inhalation of flower products and 55 % felt safe to drive 5 h or less after consumption of edible cannabis products. 13% reported that the passage of Proposition 64 increased their Likelihood of DUIC. Those with lower knowledge of Prop 64 driving related regulations were more likely to ever have been pulled over or involved in a crash while under the influence of cannabis. Conclusions: Six years after legalization implementation, there remains mixed awareness of driving-related regulations among people who currently use cannabis. Lower knowledge of regulation was associated with an increase in adverse driving outcomes. Effective messaging to increase knowledge of regulations, duration of intoxication, and promotion of safe driving behaviors is an essential step for promoting public safety after the legalization of cannabis.