title: Not just 'a few wisps': real-time measurement of tobacco smoke at entrances to office buildings.
abstract: BACKGROUND
  An unintended consequence of indoor smoking restrictions is the relocation of smoking to building entrances, where non-smokers may be exposed to secondhand smoke, and smoke from outdoor areas may drift through entrances, exposing people inside. Tobacco smoke has been linked to numerous health effects in non-smokers and there is no safe level of secondhand smoke (SHS) exposure. This paper presents data on levels of tobacco smoke inside and outside entrances to office buildings.
  
  
  METHODS
  Real-time air quality monitors were used to simultaneously measure respirable particulate matter (PM(2.5); air pollutant particles with a diameter of 2.5 μg or less) as a marker for tobacco smoke, outside and inside 28 entrances to office buildings in downtown Toronto, Ontario, in May and June 2008. Measurements were taken when smoking was and was not present within 9 m of entrances. Background levels of PM(2.5) were also measured for each session. A mixed model analysis was used to estimate levels of PM(2.5), taking into account repeated measurement errors.
  
  
  RESULTS
  Peak levels (10 s averages) of PM(2.5) were as high as 496 μg/m(3) when smoking was present. Mixed model analysis shows that the average outdoor PM(2.5) with smoking was significantly higher than the background level (p<0.0001), and significantly and positively associated with the number of lit cigarettes (p<0.0001). The average level of PM(2.5) with ≥ 5 lit cigarettes was 2.5 times greater than the average background level.
  
  
  CONCLUSIONS
  These findings support smoke-free policies at entrances to buildings to protect non-smokers from exposure to tobacco smoke.
authors.affiliation: Ontario Tobacco Research Unit, 33 Russell Street, Toronto, Ontario M5S 2S1, Canada. pam_kaufman@camh.net
authors.forename: Pamela
authors.initials: P
authors.lastname: Kaufman
authors.forename: Bo
authors.initials: B
authors.lastname: Zhang
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Bondy
authors.forename: Neil
authors.initials: N
authors.lastname: Klepeis
authors.forename: Roberta
authors.initials: R
authors.lastname: Ferrence
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods; D006801:Humans; D016273:Occupational Exposure / Q000032:analysis; D009864:Ontario; D011633:Public Facilities; D012907:Smoking; D014028:Tobacco Smoke Pollution / Q000032:analysis*; D017132:Workplace
chemical_list: D000393:Air Pollutants; D014028:Tobacco Smoke Pollution