title: Particulate Matter from Electronic Cigarettes and Conventional Cigarettes: a Systematic Review and Observational Study.
abstract: OBJECTIVE
  The aim of this study is to review the literature on the composition of aerosols from electronic cigarettes (e-cigarettes) originated by human vaping and to describe the emission of particulate matter ≤ 2.5 μm in diameter (PM(2.5)) from conventional and e-cigarettes at home in real-use conditions.
  
  
  METHODS
  We conducted a systematic literature search in PubMed and Web of Science. We measured PM(2.5) in four different homes: one from a conventional cigarette smoker, one from an e-cigarette user, and two from non-smokers.
  
  
  RESULTS
  The review identified eight previous investigations on the composition of aerosols from e-cigarettes originated by human vaping and indicated that emissions from e-cigarettes can contain potential toxic compounds such as nicotine, carbonyls, metals, and organic volatile compounds, besides particulate matter. In the observational study, the PM(2.5) median concentration was 9.88 μg/m³ in the e-cigarette user home and 9.53 and 9.36 μg/m³ in the smoke-free homes, with PM(2.5) peaks concurrent with the e-cigarette puffs.
  
  
  CONCLUSIONS
  Both the literature review and the observational study indicate that e-cigarettes used under real-conditions emit toxicants, including PM(2.5). Further research is needed to characterize the chemicals emitted by different types of e-cigarettes and to assess secondhand exposure to e-cigarette aerosol using biological markers.
authors.affiliation: Tobacco Control Unit, Cancer Prevention and Control Program, Institut Català d'Oncologia, WHO Collaborating Center for Tobacco Control, L'Hospitalet de Llobregat, Barcelona, Spain. efernandez@iconcologia.net.|Cancer Prevention and Control Group, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain. efernandez@iconcologia.net.|School of Medicine, Universitat de Barcelona, Barcelona, Spain. efernandez@iconcologia.net.
authors.forename: Esteve
authors.initials: E
authors.lastname: Fernández
authors.affiliation: Tobacco Control Unit, Cancer Prevention and Control Program, Institut Català d'Oncologia, WHO Collaborating Center for Tobacco Control, L'Hospitalet de Llobregat, Barcelona, Spain. mballbe@iconcologia.net.|Cancer Prevention and Control Group, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain. mballbe@iconcologia.net.|Addictions Unit, Institute of Neurosciences, Hospital Clínic de Barcelona, Barcelona, Spain. mballbe@iconcologia.net.
authors.forename: Montse
authors.initials: M
authors.lastname: Ballbè
authors.affiliation: Tobacco Control Unit, Cancer Prevention and Control Program, Institut Català d'Oncologia, WHO Collaborating Center for Tobacco Control, L'Hospitalet de Llobregat, Barcelona, Spain. xisca.sureda@gmail.com.|Cancer Prevention and Control Group, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain. xisca.sureda@gmail.com.|Department of Preventive Medicine, Universidad de Alcalá, Alcalá de Henares, Spain. xisca.sureda@gmail.com.
authors.forename: Xisca
authors.initials: X
authors.lastname: Sureda
authors.affiliation: Tobacco Control Unit, Cancer Prevention and Control Program, Institut Català d'Oncologia, WHO Collaborating Center for Tobacco Control, L'Hospitalet de Llobregat, Barcelona, Spain. mfu@iconcologia.net.|Cancer Prevention and Control Group, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain. mfu@iconcologia.net.|School of Medicine, Universitat de Barcelona, Barcelona, Spain. mfu@iconcologia.net.
authors.forename: Marcela
authors.initials: M
authors.lastname: Fu
authors.affiliation: Cancer Prevention and Control Group, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain. esteve.salto@gencat.cat.|School of Medicine, Universitat de Barcelona, Barcelona, Spain. esteve.salto@gencat.cat.|Health Plan Directorate, Ministry of Health, Generalitat de Catalunya, Spain. esteve.salto@gencat.cat.
authors.forename: Esteve
authors.initials: E
authors.lastname: Saltó
authors.affiliation: Tobacco Control Unit, Cancer Prevention and Control Program, Institut Català d'Oncologia, WHO Collaborating Center for Tobacco Control, L'Hospitalet de Llobregat, Barcelona, Spain. jmmartinez@iconcologia.nets.|Cancer Prevention and Control Group, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain. jmmartinez@iconcologia.nets.|Biostatistics Unit, Department of Basic Sciences, Universitat Internacional de Catalunya, Sant Cugat del Vallès, Spain. jmmartinez@iconcologia.nets.
authors.forename: Jose M
authors.initials: JM
authors.lastname: Martínez-Sánchez
mesh_terms: D000336:Aerosols / Q000737:chemistry*; D016902:Air Pollution, Indoor / Q000032:analysis; D066300:Electronic Nicotine Delivery Systems; D004784:Environmental Monitoring / Q000379:methods; D015386:Hazardous Substances; D006801:Humans; D009538:Nicotine / Q000032:analysis; D052638:Particulate Matter / Q000032:analysis* / Q000737:chemistry; D062789:Tobacco Products / Q000032:analysis*; D055549:Volatile Organic Compounds / Q000032:analysis
chemical_list: D000336:Aerosols; D015386:Hazardous Substances; D052638:Particulate Matter; D055549:Volatile Organic Compounds; D009538:Nicotine
keywords: E-cigarette; Electronic cigarette; Electronic nicotine delivery system; Particulate matter; Tobacco smoke pollution