How Is Exposure to Tobacco Outlets Within Activity Spaces Associated With Daily Tobacco Use Among Youth? A Mediation Analysis.

We investigated associations between exposure to tobacco outlets within activity spaces and daily tobacco use, and whether exposure to adults or peers using tobacco mediate these relationships. We used Geographic Ecological Momentary Assessment data over 14 days from 85 youth aged 16-20 years in eight mid-sized California city areas. Tobacco outlet addresses and global positioning systems locations were geocoded and activity spaces were constructed by joining sequential points. We assessed daily number of tobacco outlets within 50 or 100 m of activity space polylines and number of minutes participants were within 50 or 100 m of tobacco outlets each day; daily use of tobacco; and whether participants saw (1) adults and (2) people their age (peers) using tobacco each day. Controlling for demographics, results of multilevel structural equation models showed no association between number of tobacco outlets within 50 m of polylines and tobacco use (probit regression coefficient: 0.01, p = .82). However, we found evidence of an indirect effect (p = .001) through daily exposure to peers using tobacco. Specifically, greater number of tobacco outlets within 50 m of polylines was positively associated with seeing peers use tobacco (probit regression coefficient: 0.10, p < .001). In turn, seeing peers use tobacco was positively associated with tobacco use on that day (probit regression coefficient: 2.23, p < .001). Similar results were found for number of tobacco outlets within 100 m of polylines. Exposure to tobacco outlets within activity spaces affects youth tobacco use through daily exposure to peers who use tobacco. Using real-time-ordered data, this article examines whether exposure to adults and peers using tobacco mediate associations between exposure to tobacco outlets within activity spaces and daily tobacco use among youth. Results suggest that exposure to tobacco outlets within activity spaces affects daily tobacco use through exposure to peers who use tobacco. These findings provide additional significant support for policy makers who are considering regulating the number and density of tobacco retailers and point to the importance of interventions focused on peer tobacco use and youths' daily environments to reduce tobacco use.