Perceived threat and fear responses to e cigarette warning label messages: Results from 16 focus groups with U.S. youth and adults PLOS One Electronic cigarette research briefing November 2016 This research briefing is part of a series of monthly updates aiming to Vaping on the rise in U.S., especially among young people Pew Research Center E cigarettes and youth: Patterns of use, potential harms, and recommendations ScienceDirect