title: Effects of HEPA air cleaners on unscheduled asthma visits and asthma symptoms for children exposed to secondhand tobacco smoke.
abstract: OBJECTIVE
  The goal was to test the effects of high-efficiency, particulate-arresting (HEPA) air cleaners on unscheduled asthma visits and symptoms among children with asthma exposed to secondhand smoke.
  
  
  METHODS
  We enrolled 225 eligible children who were 6 to 12 years of age, had physician-diagnosed asthma, and were exposed to ≥5 cigarettes per day. We conducted a double-blind, randomized trial. Children were assigned randomly to receive 2 active or inactive HEPA air cleaners.
  
  
  RESULTS
  Of 225 enrolled children, 110 (49%) were assigned to the intervention group and 115 (51%) to the control group; 215 (95%) completed the trial. During the trial, there were 42 fewer unscheduled asthma visits among children in the intervention group (18.5% [95% confidence interval: 1.25%-82.75%]; P = .043), compared with those in the control group, after adjustment for baseline differences. There was a significant difference in the reductions of levels of particles of >0.3 μm according to group assignment; there was a 25% reduction in particle levels in the intervention group, compared with a 5% reduction in the control group (P = .026). There were no significant differences in parent-reported asthma symptoms, exhaled nitric-oxide levels, air nicotine levels, or cotinine levels according to group assignment.
  
  
  CONCLUSIONS
  These results hold promise for using HEPA air cleaners as part of a multifaceted strategy to reduce asthma morbidity, but further research is necessary before they can be recommended routinely for the medical management of asthma.
authors.affiliation: Child and Family Research Institute, British Columbia Children's Hospital and Faculty of Health Sciences, Simon Fraser University, Vancouver, British Columbia, Canada. blanphear@sfu.ca
authors.forename: Bruce P
authors.initials: BP
authors.lastname: Lanphear
authors.forename: Richard W
authors.initials: RW
authors.lastname: Hornung
authors.forename: Jane
authors.initials: J
authors.lastname: Khoury
authors.forename: Kimberly
authors.initials: K
authors.lastname: Yolton
authors.forename: Michelle
authors.initials: M
authors.lastname: Lierl
authors.forename: Amy
authors.initials: A
authors.lastname: Kalkbrenner
mesh_terms: D000389:Air Conditioning / Q000295:instrumentation; D001249:Asthma / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control*; D002648:Child; D002675:Child, Preschool; D004311:Double-Blind Method; D004781:Environmental Exposure / Q000009:adverse effects* / Q000517:prevention & control*; D005260:Female; D006801:Humans; D008297:Male; D014028:Tobacco Smoke Pollution / Q000009:adverse effects* / Q000517:prevention & control*
chemical_list: D014028:Tobacco Smoke Pollution