title: Air filtration units in homes with cats: can they reduce personal exposure to cat allergen?
abstract: BACKGROUND
  Domestic air filtration units have previously been shown to cause a dramatic fall in airborne pet allergen levels in homes with pets. Clinical trials of air filtration units, however, have failed to reveal a significant beneficial effect. Personal pet allergen exposure during air filtration unit use has never been measured.
  
  
  OBJECTIVE
  To determine the effect of air filtration on inhaled cat allergen exposure in homes with cats.
  
  
  METHODS
  Nasal air samplers were worn to measure personal cat allergen exposure. The study was carried out in five homes with cats on 4 separate days examining four experimental conditions (cat absent or present, air filtration off or on). The two operators collected four baseline samples and two 15-min samples/h over three consecutive hours. Cat allergen-bearing particles were detected by immunoblotting and allergen concentrations measured by amplified enzyme-linked immunosorbent assay (ELISA).
  
  
  RESULTS
  There was a significant reduction in the quantity of the inhaled Fel d 1 when the air cleaner was used with the cat in the room. Fel d 1 halo counts (detransformed means) were 29.3 at baseline, 11.8 after 1 h, 10.0 after 2 h and 14.1 after 3 h, with no change on control days (P = 1.00). With the cat elsewhere in the house, a marginal, but statistically significant reduction was observed only after 3 h with the use of air cleaner (Fel d 1 halo count: baseline 12.4; 3 h 5.5; P = 0.01).
  
  
  CONCLUSIONS
  The use of air filtration units appears to result in a much smaller reduction of inhaled cat allergen exposure than suggested by previous studies using standard air samplers. Cat removal remains the best advice to cat-allergic patients who experience symptoms upon exposure.
authors.affiliation: North-west Lung Research Centre, Wythenshawe Hospital, Southmoor Road, Manchester, UK. rgore@fs1.with.man.ac.uk
authors.forename: R B
authors.initials: RB
authors.lastname: Gore
authors.forename: S
authors.initials: S
authors.lastname: Bishop
authors.forename: B
authors.initials: B
authors.lastname: Durrell
authors.forename: L
authors.initials: L
authors.lastname: Curbishley
authors.forename: A
authors.initials: A
authors.lastname: Woodcock
authors.forename: A
authors.initials: A
authors.lastname: Custovic
mesh_terms: D000389:Air Conditioning; D016902:Air Pollution, Indoor; D000704:Analysis of Variance; D000818:Animals; D002415:Cats; D004781:Environmental Exposure; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D006023:Glycoproteins / Q000032:analysis*; D006801:Humans; D015151:Immunoblotting / Q000379:methods; D013997:Time Factors
chemical_list: D006023:Glycoproteins; C059296:Fel d 1 protein, Felis domesticus