title: Grass pollen counts, air pollution levels and allergic rhinitis severity.
abstract: BACKGROUND
  Little is known about the relation between allergic rhinitis severity and airborne pollen in combination with air pollutants.
  
  
  OBJECTIVE
  To model the risk of suffering from severe seasonal allergic rhinitis (SAR) as a function of both pollen count and air pollution levels in a large nationwide sample of patients whose SAR was diagnosed by a physician and confirmed by skin prick test positivity or specific immunolglobulin E to common aeroallergens.
  
  
  METHODS
  The severity of SAR symptoms was estimated with the Symptomatic Global Score (SGS) among 36,397 patients suffering from an untreated and uncomplicated SAR between May and August 2004 in metropolitan France. Patients who had an SGS in the upper third quartile were classified as suffering from severe SAR. A multilevel model relating SAR severity, pollen and air pollution was used to take into account the hierarchical data structure.
  
  
  RESULTS
  18.9% of the 17,567 urban patients retained for the analysis suffered from severe rhinitis. At the Lag0 (day of the visit), a rise of 60 grass pollen grains/m(3) increased the risk of suffering from a severe SAR form by 8% in the multileveled model after adjusting for potential confounders and air pollution levels. Results were also confirmed in the subsample of individuals with documented sensitization to grass pollen.
  
  
  CONCLUSIONS
  Grass pollen count aggravated SAR in terms of symptoms in our nationwide sample. These findings confirm the need for proper treatment and preventive measures in SAR patients sensitized to grass pollen.
authors.affiliation: INSERM, Paris, France. annesi-maesano@u707.jussieu.fr
authors.forename: Isabella
authors.initials: I
authors.lastname: Annesi-Maesano
authors.forename: Sarah
authors.initials: S
authors.lastname: Rouve
authors.forename: Hélène
authors.initials: H
authors.lastname: Desqueyroux
authors.forename: Roger
authors.initials: R
authors.lastname: Jankovski
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Klossek
authors.forename: Michel
authors.initials: M
authors.lastname: Thibaudon
authors.forename: Pascal
authors.initials: P
authors.lastname: Demoly
authors.forename: Alain
authors.initials: A
authors.lastname: Didier
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000397:Air Pollution / Q000009:adverse effects / Q000706:statistics & numerical data*; D002648:Child; D005260:Female; D005602:France / Q000453:epidemiology; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology; D015994:Incidence; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D006109:Poaceae / Q000009:adverse effects* / Q000276:immunology; D011058:Pollen / Q000009:adverse effects* / Q000276:immunology; D015995:Prevalence; D006255:Rhinitis, Allergic, Seasonal / Q000175:diagnosis / Q000453:epidemiology* / Q000276:immunology; D012306:Risk; D012720:Severity of Illness Index; D012882:Skin Tests; D055815:Young Adult
chemical_list: D007073:Immunoglobulin E