title: Prevalence and distribution of indoor allergens in Singapore.
abstract: OBJECTIVE
  Immediate hypersensitivity to indoor allergens is known to be associated with allergic asthma. This study evaluated the prevalence and distribution of six indoor allergens in 956 dust samples obtained from homes, childcare centres, schools, and a hospital in tropical Singapore. Seasonality of mite allergens was also assessed.
  
  
  METHODS
  The major allergens of the Dermatophagoides spp. dust mites, Der p 1 and Der f 1; major cat and dog allergens, Can f 1 (dog) and Fel d 1 (cat); and cockroach, Bla g 1, were measured by specific enzyme immunoassays. Allergen levels of the storage mite, Blomia tropicalis (Blo t), were measured by a fluorescent allergosorbent test (FAST) inhibition assay.
  
  
  RESULTS
  Our results showed that homes had significantly higher concentrations and prevalence of allergens compared with the other locations, except for Bla g 1, where higher mean levels were found in schools. Within the homes, the highest concentrations of mite allergens were found in mattresses (geometric mean: 1.2 microg/g dust Der p 1; 2717 Allergen Units per gram dust [AU/g] Blo t), and carpets (1.5 microg/g Der p 1; 1620 AU/g Blo t), whilst Bla g 1 was mainly concentrated in the storerooms (geometric mean = 3.5 units/g) and kitchens (geometric mean = 5.1 units/g). The major cat and dog allergens were well distributed and not confined to homes with pets. Their highest levels were found in dust of soft furnishings, carpets and mattresses. There was an absence of significant seasonal variation in Der p 1, Der f 1 and Blo t levels in the homes over a 1 year period.
  
  
  CONCLUSIONS
  The results indicate that compared with public places, the home consitutes a major reservior of indoor allergens. Allergens of the storage mite, B. tropicalis, should be considered as a major allergenic component of dust in Singapore.
authors.affiliation: Department of Paediatrics, National University of Singapore.
authors.forename: L
authors.initials: L
authors.lastname: Zhang
authors.forename: F T
authors.initials: FT
authors.lastname: Chew
authors.forename: S Y
authors.initials: SY
authors.lastname: Soh
authors.forename: F C
authors.initials: FC
authors.lastname: Yi
authors.forename: S Y
authors.initials: SY
authors.lastname: Law
authors.forename: D Y
authors.initials: DY
authors.lastname: Goh
authors.forename: B W
authors.initials: BW
authors.lastname: Lee
mesh_terms: D016902:Air Pollution, Indoor / Q000032:analysis*; D000485:Allergens / Q000032:analysis* / Q000276:immunology; D000818:Animals; D039741:Antigens, Dermatophagoides; D052179:Antigens, Plant; D001249:Asthma / Q000453:epidemiology; D002415:Cats; D003058:Cockroaches / Q000276:immunology; D004285:Dogs; D004391:Dust / Q000032:analysis; D004777:Environment; D005069:Evaluation Studies as Topic; D005455:Fluorescent Antibody Technique; D006023:Glycoproteins / Q000032:analysis / Q000276:immunology; D006796:Household Work; D006798:Housing; D006801:Humans; D007118:Immunoassay; D007073:Immunoglobulin E / Q000276:immunology / Q000378:metabolism; D007374:Interior Design and Furnishings; D015995:Prevalence; D012574:Schools; D012621:Seasons; D012846:Singapore / Q000453:epidemiology
chemical_list: D000485:Allergens; D039741:Antigens, Dermatophagoides; D052179:Antigens, Plant; D004391:Dust; D006023:Glycoproteins; C105482:allergen Bla g 1; C094701:allergen Blo t 5; C091462:allergen Can f I; D007073:Immunoglobulin E; C059296:Fel d 1 protein, Felis domesticus