title: The reduction of rhinitis symptoms by nasal filters during natural exposure to ragweed and grass pollen.
abstract: BACKGROUND
  Prototype nasal filters were developed to collect inhaled pollen. This study evaluated the efficacy of the filters for prevention of rhinitis symptoms during acute outdoor pollen exposure.
  
  
  METHODS
  A randomized double-blind design was used. Subjects (n=46) with a history of autumn exacerbation of rhinitis and positive skin test to ragweed, Bermuda and/or Bahia grass wore either active or placebo nasal filters for 2 h in autumn in a park containing these species. Major and Total Symptoms scores were recorded at 0, 30, 60, 90 and 120 min.
  
  
  RESULTS
  Subjects wearing active nasal filters had significantly reduced scores, at all time-points compared with placebo group (all P <0.05). Of 14 individual symptoms measured, seven were significantly reduced (number of sneezes, runny nose, itchy nose, sniffles, itchy throat; itchy eyes and watery eyes) and another three showed a trend towards lower severity. The nasal filters also enabled the resolution of existing symptoms. Maximal difference in symptoms was seen immediately after subjects had spent 20 min sitting beside a large patch of ragweed.
  
  
  CONCLUSIONS
  This is the first clinical trial of a nasal filter. The results suggest it has potential for enhancing rhinitis management during acute allergen exposure.
authors.affiliation: Woolcock Institute of Medical Research, Royal Prince Alfred Hospital, University of Sydney, New South Wales, Australia.
authors.forename: T J
authors.initials: TJ
authors.lastname: O'Meara
authors.forename: J K
authors.initials: JK
authors.lastname: Sercombe
authors.forename: G
authors.initials: G
authors.lastname: Morgan
authors.forename: H K
authors.initials: HK
authors.lastname: Reddel
authors.forename: W
authors.initials: W
authors.lastname: Xuan
authors.forename: E R
authors.initials: ER
authors.lastname: Tovey
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D031164:Ambrosia; D004311:Double-Blind Method; D004781:Environmental Exposure; D004867:Equipment Design; D005260:Female; D005374:Filtration / Q000295:instrumentation*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009296:Nasal Cavity; D010342:Patient Acceptance of Health Care; D006109:Poaceae; D011058:Pollen; D006255:Rhinitis, Allergic, Seasonal / Q000503:physiopathology / Q000517:prevention & control*; D012720:Severity of Illness Index