title: Upper-air observation indicators predict outbreaks of asthma exacerbations among elementary school children: integration of daily environmental and school health surveillance systems in Pennsylvania.
abstract: OBJECTIVE
  To determine whether a relationship exists between asthma exacerbations among elementary school children and daily upper-air observations (temperature, relative humidity, dew point, and mixing ratio) and, if so, to derive a mathematical model that predicts asthma exacerbations among children.
  
  
  METHODS
  Using an ecological study design, school health records of 168,825 elementary school students enrolled in the Health eTools for Schools program within 49 Pennsylvania counties were analyzed. Data representing asthma exacerbations were originally recorded by school nurses as the type of treatment given to a student during a clinic visit on a particular day. Daily upper-air measurements from ground level to the 850 mb pressure level, covering a radius of 800 km around Pittsburgh, PA, were obtained. The Wilcoxon two-sample test was used to identify associations. A generalized estimating equation model was used to predict the occurrence of more than 48 asthma exacerbations, the daily mean for 2008-2010.
  
  
  RESULTS
  Surveillance of asthma among school children in Pennsylvania increased over 3 years. The greatest occurrence was in the fall, followed by summer, spring, and winter. Annual averages of upper-air observations were significantly different between seasons (p < .02). Upper-air temperature, dew point, and mixing ratio above their 3-year mean values and upper-air relative humidity ≥ 50% were significantly associated with occurrence of asthma exacerbations (p < .011).
  
  
  CONCLUSIONS
  Monitoring of upper-air observation data over time can be a reliable means for predicting increases of asthma exacerbations among elementary school children. Such predictions could help parents and school nurses implement effective precautionary measures.
authors.affiliation: Department of Applied Health Science, Indiana University, Bloomington, IN 47403, USA.
authors.forename: Ahmed H
authors.initials: AH
authors.lastname: Youssefagha
authors.forename: David K
authors.initials: DK
authors.lastname: Lohrmann
authors.forename: Wasantha P
authors.initials: WP
authors.lastname: Jayawardene
authors.forename: Gamal S
authors.initials: GS
authors.lastname: El Afandi
mesh_terms: D000388:Air / Q000032:analysis*; D001249:Asthma / Q000453:epidemiology* / Q000503:physiopathology; D002648:Child; D003430:Cross-Sectional Studies; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D008297:Male; D015233:Models, Statistical; D010414:Pennsylvania / Q000453:epidemiology; D011159:Population Surveillance; D012621:Seasons; D018709:Statistics, Nonparametric; D013334:Students