Abstract
BACKGROUND: We investigated youth daily activity spaces, travel patterns, exposure to tobacco retail marketing, and tobacco and cannabis use and co-use. METHODS: Data included 1,060 daily assessments from 100 participants (16-20 years old) in 8 California cities. Using GPS-enabled smartphones with a survey application, youth completed brief daily surveys, and location coordinates were obtained at one-minute intervals. Tobacco outlets in study cities were visited by observers to record outlet GPS point locations and data concerning tobacco marketing. Tobacco outlet addresses and GPS location coordinates were geocoded. Activity spaces were constructed by joining sequential location points. Measures included the number of outlets with outdoor tobacco marketing within 50 m of activity space polylines and the amount of time participants were within 50 m of these outlets each day. Participants also reported tobacco and cannabis use and whether they saw tobacco ads by their neighborhood, school, workplace, and anywhere else each day. Additionally each day they reported how much time they traveled by different modes of transportation, with parents/guardians, and with friends. RESULTS: In mixed effects multinomial regression models, perceived exposure to tobacco marketing was associated with co-use of tobacco and cannabis on a given day (RRR = 1.66, p < 0.05). Although perceived exposure to tobacco marketing was not associated with tobacco use only, moderation analysis indicated that the likelihood of tobacco use was greater among youth who walked/biked/skated more (RRR = 5.22, p < 0.05). CONCLUSION: Perceived exposure to tobacco marketing contributes to youth tobacco and cannabis use or co-use, especially for those who travel by walking/biking/skating.