title: Relationship of outdoor air quality to pediatric asthma exacerbations.
abstract: BACKGROUND
  Although exposure to outdoor air pollutants has been shown to be associated with exacerbations of asthma, there are relatively few admissions for asthma to Cincinnati Children's Hospital, Cincinnati, OH during the summer months when air quality tends to be worst.
  
  
  OBJECTIVE
  The objective of this study was to determine the relationship of outdoor air quality parameters to asthma exacerbations in children.
  
  
  METHODS
  The number of emergency room visits and hospitalizations for asthma were determined by review of emergency department logs and the hospital computer database. Outdoor air concentrations of ozone, particulates of < 10 microm diameter (PM-10), pollens, and fungal spores were obtained from the Hamilton County Department of Environmental Services. Multiple regression analysis was performed, looking for relationships between the daily number of asthma visits and the air quality data for the same day and for 1 through 5 days before the visits.
  
  
  RESULTS
  A significant association was found between the number of asthma visits and the daily pollen count (P = 0.014, SE = 0.001). The effect was stronger for visits 1, 2, and 3 days after the pollen count (P < 0.001 for pollen count lagged 3 days). High PM-10 counts were synergistic with the pollen count as a predictor of asthma visits. There was no association between asthma visits and the ozone concentration or fungal spore count.
  
  
  CONCLUSIONS
  Exacerbations of asthma severe enough to require visits to the hospital were associated with elevated concentrations of airborne pollens and particulates, with a significant delayed effect. Ozone, in the concentrations measured here, was not a risk factor for severe asthma exacerbations in children.
authors.affiliation: Division of Pulmonary Medicine, Allergy and Immunology, Children's Hospital Medical Center, Cincinnati, Ohio 45229, USA. michelle.lierl@chmcc.org
authors.forename: Michelle B
authors.initials: MB
authors.lastname: Lierl
authors.forename: Richard W
authors.initials: RW
authors.lastname: Hornung
mesh_terms: D000393:Air Pollutants / Q000009:adverse effects* / Q000032:analysis; D001249:Asthma / Q000139:chemically induced* / Q000628:therapy; D002648:Child; D002669:Child Welfare; D004636:Emergency Service, Hospital; D006801:Humans; D015588:Observer Variation; D009820:Ohio; D010126:Ozone / Q000009:adverse effects; D010316:Particle Size; D011058:Pollen / Q000009:adverse effects; D011237:Predictive Value of Tests; D012044:Regression Analysis; D012621:Seasons; D013172:Spores, Fungal; D013223:Statistics as Topic
chemical_list: D000393:Air Pollutants; D010126:Ozone