References: Air Cleaners

These citations on the effect air cleaners on reducing indoor allergen exposure are provided for allergists and other medical professionals. A full understanding of the role of air purifiers in allergen avoidance requires a critical reading of the complete text of these and other studies on allergen-avoidance, air cleaner types, the aerobiology of indoor allergens, and allergic conditions including asthma, allergic rhinitis, and atopic dermatitis.

A placebo-controlled trial of a HEPA air cleaner in the treatment of cat allergy.

AUTHORS: Wood RA; Johnson EF; Van Natta ML; Chen PH; Eggleston PA

AUTHOR AFFILIATION: Department of Pedatrics, Division of Allergy and Immunology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.

SOURCE: American Journal of Respiratory and Critical Care Medicine 1998 Jul; 158(1): 115-20

CITATION IDS: PMID: 9655716 UI: 98325291


To evaluate the effect of a room high-efficiency particulate air (HEPA) cleaner on cat-induced asthma and rhinitis, 35 cat-allergic subjects who were living with one or more cats were studied in a double-blind, placebo controlled trial. After a 1 mo baseline period, subjects' bedrooms were equipped with an active or placebo air cleaner for the following 3 mo. Evaluations included monthly measurement of cat-allergen levels, daily morning, afternoon, and nighttime nasal- and chest-symptom scores, twice-daily measurement of peak-flow rates, daily medication scores, monthly spirometry, and methacholine (MCh) challenge testing before and after the study. Airborne allergen levels were reduced in the active-filter group as compared with the placebo group (p=0.045). However, no differences were detected in settled-dust allergen levels (p=0.485), morning, afternoon, or nighttime nasal-symptom scores, (p=0.769, 0.534, and 0.138), chest-symptom scores (p=0.388, 0.179, and 0.215), sleep disturbance (p=0.101), morning or afternoon peak-flow rates (p=0.424 and 0.679), or rescue medication use (nasal, p=0.164, chest, p=0.650), respectively. Although the combination of a HEPA room air cleaner, mattress and pillow covers, and cat exclusion from the bedroom did reduce airborne cat allergen levels, no effect on disease activity was detected for any parameter studied.

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: American Review of Respiratory Disease 1991 Jun; 143(6): 1334-9

CITATION IDS: PMID: 2048821 UI: 91264354


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.

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: Journal of Allergy and Clinical Immunology 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.

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.

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