title: Respiratory symptoms following wildfire smoke exposure: airway size as a susceptibility factor.
abstract: BACKGROUND
  Associations between exposure to smoke during wildfire events and respiratory symptoms are well documented, but the role of airway size remains unclear. We conducted this analysis to assess whether small airway size modifies these relationships.
  
  
  METHODS
  We analyzed data from 465 nonasthmatic 16- to 19-year-old participants in the Children's Health Study. Following an outbreak of wildfires in 2003, each student completed a questionnaire about smoke exposure, dry and wet cough, wheezing, and eye symptoms. We used log-binomial regression to evaluate associations between smoke exposure and fire-related health symptoms, and to assess modification of the associations by airway size. As a marker of airway size, we used the ratio of maximum midexpiratory flow to forced vital capacity.
  
  
  RESULTS
  Forty percent (186 of 465) of this population (including students from 11 of 12 surveyed communities) reported the odor of wildfire smoke at home. We observed increased respiratory and eye symptoms with increasing frequency of wildfire smoke exposure. Associations between smoke exposure and having any of 4 respiratory symptoms were stronger in the lowest quartile of the lung function ratio (eg, fire smoke 6+ days: prevalence ratio: 3.8; 95% confidence interval (CI = 2.0-7.2), compared with the remaining quartiles (fire smoke 6+ days: prevalence ratio = 2.0; 1.2-3.2). Analysis of individual symptoms suggests that this interaction may be strongest for effects on wheezing.
  
  
  CONCLUSIONS
  Small airways may serve as a marker of susceptibility to effects of wildfire smoke. Future studies should investigate the role of airway size for more common exposures and should include persons with asthma.
authors.affiliation: Centre for Research in Environmental Epidemiology, Barcelona, Spain.
authors.forename: Maria C
authors.initials: MC
authors.lastname: Mirabelli
authors.forename: Nino
authors.initials: N
authors.lastname: Künzli
authors.forename: Edward
authors.initials: E
authors.lastname: Avol
authors.forename: Frank D
authors.initials: FD
authors.lastname: Gilliland
authors.forename: W James
authors.initials: WJ
authors.lastname: Gauderman
authors.forename: Rob
authors.initials: R
authors.lastname: McConnell
authors.forename: John M
authors.initials: JM
authors.lastname: Peters
mesh_terms: D000293:Adolescent; D002140:California / Q000453:epidemiology; D004781:Environmental Exposure; D005260:Female; D005390:Fires; D005540:Forced Expiratory Flow Rates; D006801:Humans; D008297:Male; D010614:Pharynx / Q000033:anatomy & histology*; D012129:Respiratory Function Tests; D012131:Respiratory Insufficiency / Q000453:epidemiology* / Q000503:physiopathology; D012906:Smoke / Q000009:adverse effects*; D011795:Surveys and Questionnaires; D055815:Young Adult
chemical_list: D012906:Smoke