Air Purifiers and Allergy Relief

TITLE: Clinical effects of air cleaners in homes of asthmatic children sensitized to pet allergens.
AUTHORS: van der Heide S; van Aalderen WM; Kauffman HF; Dubois AE; de Monchy JG
AUTHOR AFFILIATION: Department of Allergology, Clinic for Internal Medicine, Beatrix Children's Hospital from the University Hospital Groningen, Groningen.
SOURCE: J Allergy Clin Immunol 1999 Aug; 104(2 Pt 1): 447-51
CITATION IDS: PMID: 10452769 UI: 99382343
BACKGROUND: Exposure to cat and dog allergens is very common in the Western World and is a serious cause of asthma in sensitized subjects.
OBJECTIVE: We sought to study the clinical effects of air cleaners in living rooms and bedrooms of asthmatic children sensitized to cat or dog allergens.
METHODS: Twenty asthmatic children sensitized to pet allergens (cat/dog) and with an animal at home participated in a double-blind, placebo-controlled, cross-over study in which the effects of air cleaners placed in the living room and bedroom for 3 months were compared with the effects of sham air cleaners. Before and after each study period, lung function, airway hyperresponsiveness (adenosine monophosphate), and peak flow variation were recorded. Cat and dog allergen levels were assessed in the filters of the air cleaners.
RESULTS: After a 3-month intervention with active air cleaners, airway hyperresponsiveness decreased significantly, showing a 1.2 doubling dose increase of PC(20) adenosine (P=.003). Peak flow amplitude also decreased (P=.045). Substantial amounts of airborne cat and dog allergen were captured by the air cleaners in living rooms and bedrooms as well. Allergen levels in floor dust were not changed.
CONCLUSIONS: In young asthmatic patients sensitized and exposed to pets in the home, application of air cleaners in living rooms and bedrooms was accompanied by a significant improvement in airway hyperresponsiveness and a decrease in peak flow amplitude.

TITLE: Airborne cat allergen (Fel d 1). Environmental control with the cat in situ.
AUTHORS: de Blay F; Chapman MD; Platts-Mills TA
AUTHOR AFFILIATION: Department of Medicine, University of Virginia, Charlottesville.
SOURCE: Am Rev Respir Dis 1991 Jun; 143(6): 1334-9
CITATION IDS: PMID: 2048821 UI: 91264354
ABSTRACT: In a house with a cat, furnishings, air-exchange rate, and the cat are all thought to influence airborne cat allergen. We carried out experiments using two separate rooms, modifying the environment, applying different cleaning techniques, and washing the cat, to analyze these sources and to design methods of reducing airborne allergen. Airborne measurements were made with a cascade impactor and a two-site monoclonal antibody-based immunometric assay for cat allergen Fel d 1. Within 30 min of entering a 30m3 clean room the cat itself was found to increase airborne Fel d 1 by 30 to 90 ng/m3. Following serial weekly washing of the cat this increase was reduced to less than or equal to 7 ng/m3, with a more marked fall in small particles (less than or equal to 2.5 microns in diameter) from 9.5 to less than or equal to 0.4 ng/m3. To study the influence of the room design we kept the cat in a room of 33 m3 for 20h/day and modified the room. This room was studied with or without furnishings and with air-exchange rates of 0.2 or 2.4 air changes per hour. Both low ventilation rate and furnishings increased the level of Fel d 1 measured 1 h after the cat was removed. However, the most striking finding was that the carpet accumulates cat allergen at approximately 100 times the level for a polished floor, that is, approximately 100 micrograms/day Fel d 1 compared with approximately 0.5 micrograms/day Fel d 1. In keeping with this, air filtration was effective at cleaning the air only if (1) there was no carpet and (2) the floor was cleaned first. The results show that airborne allergen can be dramatically reduced by a combination of washing the cat, reducing furnishings, vacuum cleaning, and air filtration. Comparison with previous results suggests that the reductions achieved may be sufficient to allow a cat-sensitive patient to live safely in the same house as a cat.

TITLE: The effect of air filtration on airborne dog allergen.
AUTHORS: Green R; Simpson A; Custovic A; Faragher B; Chapman M; Woodcock A
AUTHOR AFFILIATION: North West Lung Centre, Wythenshawe Hospital, Manchester, UK.
SOURCE: Allergy 1999 May; 54(5): 484-8
CITATION IDS: PMID: 10380790 UI: 99308487
BACKGROUND: Effective methods of reducing dog allergen are required to help alleviate symptoms in asthmatic patients sensitized to dog who refuse to part with their pet. The aim of this study was to investigate the use of the high efficiency particulate air (HEPA) filter air cleaner to reduce airborne Can f 1 in homes with a dog.
METHODS: The effect of a HEPA air cleaner was investigated in nine homes with a dog. Samples were collected from two rooms of each house concurrently, one of which contained the dog, on two separate days (active day - HEPA air cleaner on - and control day). Eight consecutive 1-h samples were collected from each room with a high-volume air sampler (airflow rate 60 l/min). Can f 1 was determined by monoclonal-polyclonal antibody-based ELISA.
RESULTS: Baseline airborne Can f 1 levels were 3.8-fold greater when sampling was performed with a dog in the room (GM 27.1 ng Can f 1/m3, range 2.633029) than when the dog was elsewhere in the house (GM 7.1 ng Can f 1/m3, range 0.69-27.2). When the dog was elsewhere in the house, airborne Can f 1 levels fell on both active and control days, but the magnitude of the reduction was significantly greater on the active days (P<0.05), and was approximately 90% from baseline. With the dog in the room, a significant fall in airborne Can f 1 was observed only on active days (75% from baseline), but not on control days (active vs control P<0.001).
CONCLUSIONS: HEPA air cleaners reduce airborne Can f 1 in homes with dogs. Furthermore, preventing the access of the dog to the bedroom and possibly the living room may reduce the total allergen load inhaled.