title: Association between climate factors, pollen counts, and childhood hay fever prevalence in the United States.
abstract: BACKGROUND
  Climate factors and pollen counts may play a role in hay fever.
  
  
  OBJECTIVE
  We sought to determine the impact of specific climate factors and pollen counts on the US prevalence of hay fever and statewide variation in prevalence.
  
  
  METHODS
  We used a merged analysis of the 2007 National Survey of Children's Health from a representative sample of 91,642 children aged 0 to 17 years and the 2006-2007 National Climate Data Center and Weather Service measurements of relative humidity (%), indoor heating degree days, precipitation, Palmer Hydrological Drought Index, clear sky and issued ultraviolet indices, stratospheric ozone levels, and outdoor air temperature and National Allergy Bureau total pollen counts. Multivariate survey logistic regression models controlled for sex, race/ethnicity, age, household income, and birthplace.
  
  
  RESULTS
  The US prevalence of hay fever in childhood was 18.0% (95% CI, 17.7% to 18.2%), with the highest prevalence in southeastern and southern states. Hay fever prevalence was significantly lower with second and third quartile mean annual relative humidity (logistic regression, P ≤ .01 for both), fourth quartile mean annual Palmer Hydrological Drought Index (P = .02), third and fourth quartile mean annual heating degree days (P < .0001 for both), and third and fourth quartile mean annual stratospheric ozone levels but increased with second, third, and fourth quartile mean annual temperature (P ≤ .02 for both), fourth quartile mean annual precipitation (P = .0007), mean total pollen counts (P = .01), and second, third, and fourth quartile issued ultraviolet index (P ≤ .0001 for all). Principal-component analysis was also used to determine the combined effects of correlated climate variables and pollen counts.
  
  
  CONCLUSIONS
  This study provides evidence of the influence of climate on the US prevalence of childhood hay fever.
authors.affiliation: Departments of Dermatology, Preventive Medicine, and Medical Social Sciences, Northwestern University, Chicago, Ill; Department of Dermatology, Beth Israel Medical Center and St Luke's-Roosevelt Hospital Center, New York, NY. Electronic address: JonathanISilverberg@Gmail.com.
authors.forename: Jonathan I
authors.initials: JI
authors.lastname: Silverberg
authors.affiliation: Department of Pediatrics, State University of New York Downstate Medical Center, Brooklyn, NY.
authors.forename: Marc
authors.initials: M
authors.lastname: Braunstein
authors.affiliation: Mount Sinai Beth Israel Medical Center, New York, NY.
authors.forename: Mary
authors.initials: M
authors.lastname: Lee-Wong
mesh_terms: D000485:Allergens / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D002980:Climate; D004777:Environment; D005260:Female; D062306:Geography, Medical; D006801:Humans; D008297:Male; D016017:Odds Ratio; D011058:Pollen / Q000009:adverse effects*; D015995:Prevalence; D006255:Rhinitis, Allergic, Seasonal / Q000453:epidemiology* / Q000209:etiology*; D012307:Risk Factors; D014481:United States / Q000453:epidemiology
chemical_list: D000485:Allergens
keywords: Hay fever prevalence; Palmer drought index; air temperature; children; indoor heating; pediatric; pollen count; precipitation; rain; relative humidity; rhinoconjunctivitis; stratospheric ozone levels; ultraviolet index