1. Department of Health Promotion, Education, and Behavior, Arnold School of Public Health, University of South Carolina , Columbia, SC , USA
2. Division of Prevention Science, Department of Medicine, University of California San Francisco , San Francisco, CA , USA
3. Division of General Internal Medicine, Department of Medicine, University of California San Francisco , San Francisco, CA , USA
4. Rescue Agency , San Diego, CA , USA
5. Center for Tobacco Control Research and Education, University of California San Francisco , San Francisco, CA , USA