title: Perceptions of Secondhand E-Cigarette Aerosol Among Twitter Users.
abstract: OBJECTIVE
  There is considerable debate among the public health community about the health risks of secondhand exposure to the aerosol from electronic cigarettes (e-cigarettes). Despite mounting scientific evidence on the chemical content of e-cigarette aerosol, public perceptions of the relative safety of secondhand e-cigarette aerosol have not been well characterized.
  
  
  METHODS
  This study collected tweets, or messages sent using Twitter, about exposure to secondhand e-cigarette aerosol over a 6-week period in 2015. Tweets were coded on sentiment about e-cigarettes (pro-, anti-, or neutral/unknown) and topic (health, social, advertisement, or unknown).
  
  
  RESULTS
  The 1519 tweets included 531 pro-e-cigarette tweets, 392 anti-e-cigarette tweets, and 596 neutral tweets. Social tweets far outnumbered health tweets (747 vs. 182, respectively). Social-focused tweets were predominantly pro-e-cigarette, whereas health-focused tweets were predominantly anti-e-cigarette.
  
  
  CONCLUSIONS
  Twitter discussions about secondhand vaping are dominated by pro-e-cigarette social tweets, although there is a presence of anti-e-cigarette social tweets and tweets about negative and positive health effects. Public health and regulatory agencies could use social media and traditional media to disseminate the message that e-cigarette aerosol contains potentially harmful chemicals and could be perceived as offensive. This study identifies the prevalent topics and opinions that could be incorporated into health education messages.
authors.affiliation: Professor of Preventive Medicine, University of Southern California, Los Angeles, CA.
authors.forename: Jennifer B
authors.initials: JB
authors.lastname: Unger
authors.affiliation: Predoctoral student, University of Southern California, Los Angeles, CA.
authors.forename: Patricia
authors.initials: P
authors.lastname: Escobedo
authors.affiliation: Postdoctoral fellow, University of Southern California, Los Angeles, CA.
authors.forename: Jon-Patrick
authors.initials: JP
authors.lastname: Allem
authors.affiliation: Project Manager, University of Southern California, Los Angeles, CA.
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Soto
authors.affiliation: Research Associate, University of Southern California, Los Angeles, CA.
authors.forename: Kar-Hai
authors.initials: KH
authors.lastname: Chu
authors.affiliation: Associate Professor, University of Southern California, Los Angeles, CA.
authors.forename: Tess
authors.initials: T
authors.lastname: Cruz
keywords: Twitter; e-cigarettes; secondhand vapor