title: [Assessment of the air quality improment of cleaning and disinfection on central air-conditioning ventilation system].
abstract: OBJECTIVE
  To assess the effect of air quality of cleaning and disinfection on central air-conditioning ventilation systems.
  
  
  METHODS
  102 air-conditioning ventilation systems in 46 public facilities were sampled and investigated based on Hygienic assessment criterion of cleaning and disinfection of public central air-conditioning systems.
  
  
  RESULTS
  Median dust volume decreased from 41.8 g/m2 to 0.4 g/m2, and the percentage of pipes meeting the national standard for dust decreased from 17.3% (13/60) to 100% (62/62). In the dust, median aerobic bacterial count decreased from 14 cfu/cm2 to 1 cfu/cm2. Median aerobic fungus count decreased from 10 cfu/cm2 to 0 cfu/cm2. The percentage of pipes with bacterial and fungus counts meeting the national standard increased from 92.4% (171/185) and 82.2% (152/185) to 99.4% (165/166) and 100% (166/166), respectively. In the ventilation air, median aerobic bacterial count decreased from 756 cfu/m3 to 229 cfu/m3. Median aerobic fungus count decreased from 382 cfu/m3 to 120 cfu/m3. The percentage of pipes meeting the national standard for ventilation air increased from 33.3% (81/243) and 62.1% (151/243) to 79.8% (292/366) and 87.7% (242/276), respectively. But PM10 rose from 0.060 mg/m3 to 0.068 mg/m3, and the percentage of pipes meeting the national standard for PM10 increased from 74.2% (13/60) to 90.2% (46/51).
  
  
  CONCLUSIONS
  The cleaning and disinfection of central air-conditioning ventilation systems could have a beneficial effect of air quality.
authors.affiliation: Tianjin Centers for Disease Control and Prevention, Tianjin 300011, China. liuhongliang@cdctj.gov.cn
authors.forename: Hongliang
authors.initials: H
authors.lastname: Liu
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.forename: Lihong
authors.initials: L
authors.lastname: Feng
authors.forename: Fei
authors.initials: F
authors.lastname: Wang
authors.forename: Zhiming
authors.initials: Z
authors.lastname: Xue
mesh_terms: D000389:Air Conditioning / Q000295:instrumentation*; D000391:Air Microbiology; D016902:Air Pollution, Indoor / Q000517:prevention & control / Q000706:statistics & numerical data*; D004203:Disinfection; D004391:Dust / Q000032:analysis; D006801:Humans; D052638:Particulate Matter / Q000032:analysis; D011786:Quality Control; D014691:Ventilation / Q000295:instrumentation*
chemical_list: D004391:Dust; D052638:Particulate Matter