title: Mechanical systems versus smoking bans for secondhand smoke control.
abstract: BACKGROUND
  Despite international efforts to implement smoking bans, several national legislations still allow smoking and recommend mechanical systems, such as ventilation and air extraction, to eliminate secondhand smoke (SHS) health-related risks. We aimed to quantify the relative contribution of mechanical systems and smoking bans to SHS elimination.
  
  
  METHODS
  A cross-sectional study was conducted in randomly selected establishments from 4 Mexican cities (3 with no ban). SHS exposure was assessed using nicotine passive monitors. Establishment characteristics, presence of mechanical systems, and enforcement of smoking policies were obtained through direct observation and self-report. Multilevel models were used to assess relative contributions to SHS reduction.
  
  
  RESULTS
  Compared with Mexico City, nicotine concentrations were 3.8 times higher in Colima, 5.4 in Cuernavaca, and 6.4 in Toluca. Mechanical systems were not associated with reduced nicotine concentrations. Concentration differences between cities were largely explained by the presence of smoking bans (69.1% difference reduction) but not by mechanical systems (-5.7% difference reduction).
  
  
  CONCLUSIONS
  Smoking bans represent the only effective approach to reduce SHS. Tobacco control regulations should stop considering mechanical systems as advisable means for SHS reduction and opt for complete smoking bans in public places.
authors: Tobacco Research Department, National Institute of Public Health-Mexico, Mexico DF, Mexico. tbarrientos@insp.mx
authors: Tonatiuh
authors: T
authors: Barrientos-Gutierrez
authors: Benjamin C
authors: BC
authors: Amick
authors: David
authors: D
authors: Gimeno
authors: Luz M
authors: LM
authors: Reynales-Shigematsu
authors: George L
authors: GL
authors: Delclos
authors: Ronald B
authors: RB
authors: Harrist
authors: Steven H
authors: SH
authors: Kelder
authors: Eduardo
authors: E
authors: Lazcano-Ponce
authors: Mauricio
authors: M
authors: Hernandez-Ávila
mesh_terms: D000388:Air / Q000032:analysis; D003430:Cross-Sectional Studies; D006801:Humans; D008800:Mexico; D009538:Nicotine / Q000737:chemistry; D012147:Restaurants; D012907:Smoking / Q000331:legislation & jurisprudence*; D014028:Tobacco Smoke Pollution / Q000517:prevention & control*; D014691:Ventilation
chemical_list: D014028:Tobacco Smoke Pollution; D009538:Nicotine