title: [Pollutions of indoor fine particles in four types of public places and the influencing factors].
abstract: OBJECTIVE
  To study the levels of pollutions caused by fine particulate matter (PM(2.5)) in the public places and investigate the possible influencing factors.
  
  
  METHODS
  A total of 20 public places in four types such as rest room in bath center, restaurant, karaoke bars and cyber cafe in Tongzhou district in Beijing were chosen in this study; indoor and outdoor PM(2.5) was monitored by TSI sidepak AM510. Data under varying conditions were collected and analyzed, such as doors or windows or mechanical ventilation devices being opened, rooms cramped with people and smoking.
  
  
  RESULTS
  The average concentration of indoor PM(2.5) in 20 public places was (334.6 +/- 386.3) microg/m(3), ranging from 6 microg/m(3) to 1956 microg/m(3); while in bath center, restaurant, karaoke bars and cyber cafe were (116.9 +/- 100.1)microg/m(3), (317.9 +/- 235.3) microg/m(3), (750.6 +/- 521.6)microg/m(3) and (157.5 +/- 98.5) microg/m(3) respectively. The concentrations of PM(2.5) in restaurant (compared with bath center: Z = -10.785, P < 0.01; compared with karaoke bars: Z = -10.488, P < 0.01; compared with cyber cafe: Z = -7.547, P < 0.01) and karaoke bars (compared with bath center: Z = -16.670, P < 0.01; compared with cyber cafe: Z = -15.682, P < 0.01) were much higher than those in other two places. Single-factor analysis revealed that the average concentration of indoor PM(2.5) in 20 public places was associated with the number of smokers per cube meters(9.13 x 10(-3); r = 0.772, F = 26.579, P < 0.01) and ventilation score [(2.5 +/- 1.5) points; r = 0.667, F = 14.442, P < 0.01], and there were significant correlation between the average indoor and outdoor levels in restaurant [(317.9 +/- 235.3) microg/m(3), (67.8 +/- 78.9) microg/m(3); r = 0.918, F = 16.013, P = 0.028] and cyber cafe [(157.5 +/- 98.5) microg/m(3), (67.7 +/- 43.7) microg/m(3); r = 0.955, F = 30.785, P = 0.012]. Furthermore, significant correlation was observed between the average concentration of indoor PM(2.5) [(157.5 +/- 98.5) microg/m(3)]and the number of people per cube meters (288.7 x 10(-3)) in cyber cafe (r = 0.891, F = 11.615, P = 0.042). Multiple regression analysis showed that smoking (b' = 0.581, t = 3.542, P = 0.003) and ventilation (b' = -0.348, t = -2.122, P = 0.049) were the major factors that may influence the concentration of indoor PM(2.5) in four public places. With cluster analysis, the results showed that the major factors that influence the concentration of indoor PM(2.5) was the outdoor PM(2.5) levels [(49.6 +/- 39.5) microg/m(3); b = 1.556, t = 3.760, P = 0.007] when ventilation (score > 2) was relatively good. The number of smokers per cube meters (14.7 x 10(-3)) became the major influence factor when the ventilation score </= 2 (b = 140.957, t = 3.108, P = 0.013) and 51.8% increases of indoor PM(2.5) was attributed to smoking.
  
  
  CONCLUSIONS
  This study indicated that smoking was the main source of indoor PM(2.5) in public places. Outdoor PM(2.5) should be correlated with indoor PM(2.5) concentration under drafty situation.
authors.affiliation: Department of Occupational and Environmental Health Science, School of Public Health, Peking University, Beijing 100191, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
authors.forename: Fu-rong
authors.initials: FR
authors.lastname: Deng
authors.forename: Xin-biao
authors.initials: XB
authors.lastname: Guo
authors.forename: Dong-mei
authors.initials: DM
authors.lastname: Yang
authors.forename: Xiu-quan
authors.initials: XQ
authors.lastname: Teng
authors.forename: Xu
authors.initials: X
authors.lastname: Zheng
authors.forename: Jing
authors.initials: J
authors.lastname: Gao
authors.forename: Jing
authors.initials: J
authors.lastname: Dong
authors.forename: Shao-wei
authors.initials: SW
authors.lastname: Wu
mesh_terms: D016902:Air Pollution, Indoor / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods*; D052638:Particulate Matter / Q000032:analysis*; D011633:Public Facilities; D014028:Tobacco Smoke Pollution / Q000032:analysis
chemical_list: D052638:Particulate Matter; D014028:Tobacco Smoke Pollution