Real-Time Antecedents of Young Adults’ Vaping and Co-Vaping of Nicotine and Cannabis: An Ecological Momentary Assessment Study

Background: Nicotine and cannabis vaping are common among young adults and can potentially lead to adverse health consequences. Identifying real-time antecedents of vaping events may provide insights into intervention targets pertinent to these behaviors. This study aimed to examine real-time antecedents of nicotine and cannabis vaping and same-occasion co-vaping among young adults. Objective: This study aims to examine real-time antecedents of nicotine and cannabis vaping and same-occasion co-vaping among young adults. Methods: We collected ecological momentary assessments (EMAs) via a smartphone app among California young adults (ages 18‐29 y) in 2023‐2024. Participants completed four random prompts each day for 30 consecutive days. Outcomes were defined as whether participants reported being about to vape nicotine, cannabis, or both substances (same-occasion co-vaping) in a given EMA. We used mixed-effects logistic regression models to examine real-time antecedents of each outcome. Results: Overall, 113 participants (mean age 23.8 y, SD3 y, 63% female, n=70) completed 9001 EMAs. Similar antecedents of all 3 vaping outcomes were craving and using alcohol. Increased cravings for a given substance were associated with a higher likelihood of vaping that substance or co-vaping. Craving for cannabis vaping was associated with lower odds of reporting nicotine vaping (adjusted odds ratio [AOR] 0.87, 95% CI 0.82‐0.92). Feeling happier was associated with higher odds of reporting co-vaping (AOR 1.13, 95% CI 1.01‐1.27) while feeling more stressed was associated with lower odds of vaping nicotine (AOR 0.95, 95% CI 0.91‐0.98) or cannabis (AOR 0.91, 95% CI 0.86‐0.97). Seeing tobacco advertisements was associated with higher odds of vaping nicotine (AOR 3.09, 95% CI 1.48‐6.46) and co-vaping (AOR 4.15, 95% CI 1.18‐14.52). Cannabis vaping was more likely to occur in the afternoon (AOR 1.52, 95% CI 1.16‐1.98) and nighttime (AOR 1.95, 95% CI 1.45‐2.63) than in the morning. Co-vaping was also more likely to occur in the afternoon (AOR 1.59, 95% CI 1.14‐2.22) and nighttime (AOR 1.84, 95% CI 1.26‐2.71) than in the morning, but the association was not held for nicotine vaping. Nicotine vaping was more likely to occur on weekends compared to weekdays (AOR 1.25, 95% CI 1.09‐1.45), but no significant associations were found for cannabis vaping and co-vaping. Conclusions: We found similar antecedents (craving and alcohol use) and unique antecedents (mood, advertising exposure, and time of day) for nicotine vaping, cannabis vaping, and same-occasion co-vaping, suggesting targets for future vaping cessation interventions.