No full-text available
To read the full-text of this research,
you can request a copy directly from the author.
Air filtration devices in the control of indoor allergens
Abstract
There are a variety of air cleaning devices that have been developed for the control of indoor allergens and irritants. These include both portable, room-sized units, and central units for use with a home's heating and ventilation system. While air cleaners can help to reduce some allergens, such as those produced by cats and dogs, they are unlikely to work for most other indoor allergens. The use of air cleaners for the management of allergic disease is reviewed in this article, and specific recommendations for their use are provided.
... The role of air filtration in providing relief for individuals with allergic respiratory illness has been studied for more than 40 years [17,18]. Prior reviews of air filtration have focused primarily on PRACs and the effect on patient symptom scores [19][20][21]. Reisman [19] stated that the studies should focus only on IgE-proven disease and HEPA PRACs. Wood [20] concluded that while HEPA PRACs may be an option for cat and dog allergy, there was no evidence they were effective for dust mite or mold allergy. ...
... Reisman [19] stated that the studies should focus only on IgE-proven disease and HEPA PRACs. Wood [20] concluded that while HEPA PRACs may be an option for cat and dog allergy, there was no evidence they were effective for dust mite or mold allergy. Focusing only on allergies does not take into consideration the effects of PM and other indoor air pollutants. ...
... Since the Wood [20] and McDonald et al. [21] reviews, there have been 14 studies (Table 1) published that are applicable to the role of air filtration as an environmental control measure for allergic respiratory diseases. ...
Air filtration is frequently recommended as a component of environmental control measures for patients with allergic respiratory disease. Residential air filtration can be provided by whole house filtration via the home's heating, ventilation, or air conditioning system, by portable room air cleaners, or a combination of the two. Appliances to filter the sleep breathing zone also have been developed. High-efficiency whole house filtration, high-efficiency particulate air sleep zone air filtration, and high-efficiency particulate air room air cleaners all appear to provide various degrees of benefit. Recent studies of various types of filtration, used alone or as part of more comprehensive environmental control measures, are reviewed.
... Wood et al 22 found only modest reductions in airborne levels of Fel d 1 in homes with cats with a room HEPA air filter in the bedroom and no clinical benefit over placebo for cat-sensitive allergic patients. Wood,32 in his review of air filtration devices, reported 2 other studies that failed to show efficacy in subjects with dust mite allergy. A recent investigation found no effect of HEPA filtration on bronchial hyperresponsiveness in children and adolescents allergic to cats and dogs. ...
... Two open-label studies of mold-sensitive patients reported reductions in symptoms and medication use. 32 In Wood's air filtration review, 32 many HEPA filtration studies were small, with inadequate blinding, lack of measured airborne allergen concentrations, and varying air-velocity rates related to room size, location, and occupant behaviors. Wood concluded that HEPA room air cleaners might be beneficial for animal allergy in homes in which compliance for pet removal is lacking because the particulates carrying these allergens can remain airborne long enough to permit filtration and removal. ...
The allergist is generally recognized as possessing the greatest expertise in relating airborne contaminants to respiratory health, both atopic and nonatopic. Consequently, allergists are most often asked for their professional opinions regarding the appropriate use of air-cleaning equipment. This rostrum serves as a resource for the allergist and other health care professionals seeking a better understanding of air filtration.
... While a number of studies have evaluated the impact of air purifiers on allergic disease, many are limited by small sample sizes and inadequate blinding. 23 A study funded by Samsung Electronics Co., Ltd demonstrated that reducing indoor PM2.5 levels with air purifiers improved childhood asthma control test scores and mean evening peak flow rates. 4 However, since the city where the study was conducted had a very low basal PM2.5 level of 7.42 µg/m 3 , and the concentration change due to the use of air purifiers was not significant, it is thought that the symptom relief will not be significant. ...
Purpose:
To evaluate the effects of air purifiers on the concentrations of indoor air pollutants and on asthma control in children.
Materials and methods:
In this randomized crossover trial, daily use of an air purifier filter was compared with a matched placebo with the filter off. Thirty elementary school students who had asthma were enrolled and randomly allocated to one of two groups. The primary endpoints were changes in indoor air quality, asthma severity, lung function, airway inflammatory, urine microbiome, and phthalate after the installation of air purifiers. PM2.5 and CO₂ were measured as indoor air pollutants. Asthma severity was assessed in terms of both symptom and medication scores acquired using a daily questionnaire. The higher the score, the better the symptom or the less frequent the use of medication. Peak expiratory flow rate and fractional exhaled nitric oxide were also measured.
Results:
The mean age of the enrolled patients was 9.2±1.98 years. The mean concentration of PM2.5 was 17.0 μg/m³ in the filter-off condition, but significantly lower at 9.26 μg/m³ in the filter-on condition. Medication scores were 6.9 for the filter-off and 7.12 for the filter-on conditions, reflecting a statistically significant decrease in the frequency of medications used during air purifier operation. Bacterial richness, as determined using the Chao 1 index, was markedly lower in the filter-on than the filter-off condition.
Conclusion:
This study suggests that air purifiers benefit medication burden in children with asthma by reducing PM2.5 levels.
... However, only limited clinical field studies demonstrate that air cleaners significantly decrease airborne cat allergen, 11,15 and have significant clinical effects 16 . Cat allergen is a very good model to assess the efficacy of air cleaner, because it is the most difficult aeroallergen to be reduced since 20% of airborne Fel d 1 is carried in particles less than 5 µm 17 . ...
Background:
Air cleaners have been promoted for respiratory allergic disease prevention, but there is no clear clinical proof of their efficacy in allergic asthma.
Objective:
To examine the efficacy of a new air cleaner on early and late asthmatic responses in cat-allergic patients.
Methods:
This randomized, cross-over, double-blind placebo-controlled study enrolled 24 cat-asthmatic patients with GINA 1 asthma. At baseline, participants were exposed to 40 ng/m3 of airborne cat allergen for a maximum of two hours in ALYATEC® environmental exposure chamber. All participants were subsequently randomized into two groups that were exposed to cat allergen, either with active then placebo air cleaners or with placebo then active air cleaners with a 3-week interval in the EEC. This study was registered under number (NCT03928561).
Results:
Fewer patients experienced an EAR with active air cleaners (7 patients; 29.17%) than placebo (21 patients; 87.50%). The response incidence was lower with active than with placebo air cleaners. A Cox model demonstrated a significant treatment effect (hazard ratio, 0.10; P = .002). Active air cleaners also prevented late asthmatic response: 4 patients (16.67%) had a late asthmatic response with active air cleaners compared to 11 patients (45.83%) with placebo. (Prescott test P = .002). Active air cleaners also decreased the maximal severity of bronchial response (FEV1 decrease of 17.24% with active vs 25.62% with placebo air cleaners; P = .001) CONCLUSIONS: Our present results demonstrated that Intense Pure Air XL® air cleaners significantly prevented early and late asthmatic responses among cat-allergic asthmatics during cat allergen exposure in the ALYATEC environmental exposure chamber.
... If used, it is important to know the subject's allergies prior to installing a filtration unit. PRACs have been shown to be effective for removal of cat, dog, and rodent allergens, but not for dust mite or other indoor allergens [91]. Little research has been done to determine their effect on reducing fungal allergens. ...
Allergic diseases are surprisingly common, chronic health conditions. The primary location where the vast majority of people are exposed to allergens and other substances is in their home. This means it is important to understand home environments and how a home’s systems function and interact—and that how we occupy these spaces plays a crucial role in both environmental exposure and management of allergic disease. This review provides an overview of what is understood about home environmental exposure and its impact on our health, and proposes a systematic process for using a patient’s environmental history to develop individualized, manageable and cost-effective recommendations. Once occupant-related information has been gathered, a home environmental exposure assessment should be performed focused on identifying the relationships between any identified sources of contaminants and the housing systems, and conditions that may be contributing to exposure. The results and recommendations from this assessment can then be used to guide exposure-reduction efforts by patients and/or their caregivers in an effort to improve disease management. In this review, we’ll discuss three different types of home interventions—active, which must be routinely performed by the patient and/or caregiver, passive, which are interventions that work without routine, direct interaction from the homeowner, and behavioral changes in how the home environment is cleaned and maintained for long-term reduction of allergens. In this review, and others evaluated for this discussion, a significant number of home environmental assessment and intervention programs were shown to be cost effective, with the majority of programs showing a net positive return on investment. It is important to recognize that to be cost effective, the level and intensity of services offered through home visit programs need be stratified, based on the estimated health risks of the patient, in order to tailor the assessment and target the interventions to a patient's needs while maximizing cost effectiveness.
... Reviews of intervention studies using standalone air purifiers and conducted amongst free-living participants residing in their own homes to evaluate the potential health benefits began with a report by the Institute of Medicine (IOM, 2000). Others followed (Reisman, 2001;Wood, 2002;Sublett et al., 2010;Sublett, 2011), including a metaanalysis by McDonald et al. (2002), all generally assessing a subset of the same studies appraised by the IOM. On the whole, the evaluated studies were deemed to have weak designs and the reviews generally conclude that filtration devices led to only small improvements in allergy and asthma outcomes. ...
In today's ‘indoor generation’ most human activities take place within an enclosed space, characterised by a chemically diverse and complex air quality. Although source control is the universally preferred approach to reduce contaminants, this is becoming increasingly insufficient, technically unfeasible or economically unviable. The provision of adequate ventilation is also being challenged by invariably poor outdoor air quality and our quest for a low carbon economy. Whilst the former directly adds to the burden of indoor air pollution, both factors attract mitigation measures that are leading to efforts to seal off indoor spaces, which can increase exposure to endogenous indoor air pollutants, heighten health risks and curtail concentration, learning and productivity. Research to date on the role of air purification technologies in key indoor microenvironments demonstrates that air filtration produces clear reductions in indoor pollution concentrations. To confirm the optimistic modelled health/performance benefits associated with air purification further research is required, evaluating longer term interventions particularly in vulnerable populations, employing real-time sensors to quantitatively assess complete exposure profiles and optimizing technologies/strategies to remove specific indoor air pollutants (eg infiltrated versus endogenous particles, gases, chemically transformed organics) within the unique spaces where people live, learn, work and travel.
... Several groups have examined the effect of air filtration interventions on asthma and allergy symptoms. [34][35][36][37][38][39][40][41][42][43][44] We have previously demonstrated that decreased exposure to TRAP, calculated by a land-use regression model, has a clinically significant impact on asthma control in adults. 45 Living near a major roadway makes this exposure essentially unavoidable. ...
Outdoor traffic‐related airborne particles can infiltrate a building and adversely affect the indoor air quality. Limited information is available on the effectiveness of high‐efficiency particulate air (HEPA) filtration of traffic‐related particles. Here we investigated the effectiveness of portable HEPA air cleaners in reducing indoor concentrations of traffic‐related and other aerosols, including black carbon (BC), PM2.5, ultraviolet absorbing particulate matter (UVPM) (a marker of tobacco smoke), and fungal spores. This intervention study consisted of a placebo‐controlled cross‐over design, in which a HEPA cleaner and a placebo “dummy” were placed in homes for 4‐weeks each, with 48‐hour air sampling conducted prior to and during the end of each treatment period. The concentrations measured for BC, PM2.5, UVPM, and fungal spores were significantly reduced following HEPA filtration, but not following the dummy period. The indoor fraction of BC/PM2.5 was significantly reduced due to the HEPA cleaner, indicating that black carbon was particularly impacted by HEPA filtration. This study demonstrates that HEPA air purification can result in a significant reduction of traffic‐related and other aerosols in diverse residential settings.
This article is protected by copyright. All rights reserved.
... It is not clear whether fungal allergens can be removed by air filtration. A review by Wood [59] concluded that HEPA filters are not effective for reducing exposure to mites and mold but that they may be effective for removing pet allergens. Air filters were able to reduce PM 2.5 and black carbon particles in a school setting [60]. ...
Purpose of review:
The use of environmental interventions to improve outcomes in asthmatics has long been an elusive goal. While numerous interventions have been studied, the results of clinical trials have been mixed. This review aims to identify combinations of interventions that have been proven to be effective and to propose a model for using them in a clinical setting.
Recent findings:
An NIH workshop emphasized a need for research to identify effective interventions for reducing indoor exposures and improving asthma outcomes. A number of innovative measures were described, though evidence supporting their use was lacking. A recent systematic review described various interventions for which evidence is available. The greatest challenge for this approach is the same as that for the medical approach to treatment: nonadherence. Given evidence for effective interventions, control of environmental exposures should lead to improved asthma outcomes. Methods to improve adherence need to be identified.
... Previous studies have reported that particle filtration reduced adverse health effects in subjects with allergies or asthma (Sublett, 2011;Wood, 2002). The potential benefits of particle filtration on the association between reducing indoor exposure to particles from outdoor air and reductions in morbidity and mortality has been suggested in a previous review (Fisk, 2013). ...
The association of short-term air pollution filtration with cardiovascular health has been documented. However, the effect of long-term indoor air conditioner filtration on the association between air pollution and cardiovascular health is still unclear. We recruited 200 homemakers from Taipei and randomly assigned 100 of them to air filtration or control intervention; six home visits were conducted per year from 2013 to 2014. The participants under air filtration intervention during 2013 were reassigned to control intervention in 2014. The air pollution measurements consisted of particulate matter less than or equal to 2.5 μm in diameter (PM2.5) and total volatile organic compounds (VOCs); blood pressure was monitored for each participant during each visit. The following morning, blood samples were collected after air pollution monitoring. The blood samples were used to analyze biological markers, including high sensitivity-C-reactive protein (hs-CRP), 8-hydroxy-2′-deoxyguanosine (8-OHdG) and fibrinogen. Household information, including cleaning, cooking, and air conditioning, was collected by a questionnaire. Mixed-effects models were used to investigate the associations among air pollution measurements, blood pressure and biological markers. The results showed that increased levels of PM2.5 and total VOCs were associated with increased hs-CRP, 8-OHdG and blood pressure. The health variables were higher among participants in the control intervention phase than among those in the air filtration intervention phase. We concluded that air pollution exposure was associated with systemic inflammation, oxidative stress and elevated blood pressure. The long-term filtration of air pollution with an air conditioner filter was associated with cardiovascular health of adults.
... By the use of special equipment for air purification and dehumidification, the concentrations of airborne mold components (bioaerosols) can be reduced (Bernstein and Levin, 2005). Whereas HEPA filters were effective in cat and dog allergy, there was no evidence of efficacy in house dust mite or mold allergies (Wood, 2002). A meta-analysis of 10 randomized controlled studies of air filtration from the years 1973 to 1999 found a small statistically significant improvement in overall symptoms and sleep disturbances when using air purifiers, but no improvement in nasal symptoms, medication use or peak expiratory flow (PEF) (McDonald et al., 2002). ...
In April 2016, the German Society of Hygiene, Environmental Medicine and Preventative Medicine (Gesellschaft für Hygiene, Umweltmedizin und Präventivmedizin (GHUP)) together with other scientific medical societies, German and Austrian medical societies, physician unions and experts has provided an AWMF (Association of the Scientific Medical Societies) guideline ‘Medical diagnostics for indoor mold exposure’. This guideline shall help physicians to advise and treat patients exposed indoors to mold. Indoor mold growth is a potential health risk, even without a quantitative and/or causal association between the occurrence of individual mold species and health effects. Apart from the allergic bronchopulmonary aspergillosis (ABPA) and the mycoses caused by mold, there is only sufficient evidence for the following associations between moisture/mold damages and different health effects: Allergic respiratory diseases, asthma (manifestation, progression, exacerbation), allergic rhinitis, exogenous allergic alveolitis and respiratory tract infections/bronchitis. In comparison to other environmental allergens, the sensitizing potential of molds is estimated to be low. Recent studies show a prevalence of sensitization of 3-10% in the total population of Europe. The evidence for associations to mucous membrane irritation and atopic eczema (manifestation, progression, exacerbation) is classified as limited or suspected. Inadequate or insufficient evidence for an association is given for COPD, acute idiopathic pulmonary hemorrhage in children, rheumatism/arthritis, sarcoidosis, and cancer. The risk of infections from indoor molds is low for healthy individuals. Only molds that are capable to form toxins can cause intoxications. The environmental and growth conditions and especially the substrate determine whether toxin formation occurs, but indoor air concentrations are always very low. In the case of indoor moisture/mold damages, everyone can be affected by odor effects and/or impairment of well-being. Predisposing factors for odor effects can be given by genetic and hormonal influences, imprinting, context and adaptation effects. Predisposing factors for impairment of well-being are environmental concerns, anxieties, conditioning and attributions as well as a variety of diseases. Risk groups that must be protected are patients with immunosuppression and with mucoviscidosis (cystic fibrosis) with regard to infections and individuals with mucoviscidosis and asthma with regard to allergies. If an association between mold exposure and health effects is suspected, the medical diagnosis includes medical history, physical examination, conventional allergy diagnosis, and if indicated, provocation tests. For the treatment of mold infections, it is referred to the AWMF guidelines for diagnosis and treatment of invasive Aspergillus infections. Regarding mycotoxins, there are currently no validated test methods that could be used in clinical diagnostics. From the perspective of preventive medicine, it is important that mold damages cannot be tolerated in indoor environments.
... Nearly all of the studies used mechanical filters. A recent review on the effects of air filtration (Fisk 2013) considered the recently published literature and the results of prior reviews (IOM 2000;Reisman 2001;McDonald et al. 2002;Wood 2002;Sublett et al. 2010;Sublett 2011). It concluded that particle filtration could be modestly effective in reducing adverse allergy and asthma outcomes, particularly in homes with pets. ...
... Measurements of indoor air quality and pulmonary function showed statistical improvement with the unit running as compared with the placebo mode both with and without ventilation. A recent review on the effects of air filtration (Fisk 2013 Air cleaning and filtering of prior reviews (IOM 2000;Reisman 2001;McDonald et al. 2002;Wood 2002;Sublett et al. 2010;Sublett 2011). It concluded that particle filtration could be modestly effective in reducing adverse allergy and asthma outcomes, particularly in homes with pets. ...
... Nearly all of the studies used mechanical filters. A recent review on the effects of air filtration (Fisk 2013 ) considered the recently published literature and the results of prior reviews (IOM 2000; Reisman 2001; McDonald et al. 2002; Wood 2002; Sublett et al. 2010; Sublett 2011). It concluded that particle filtration could be modestly effective in reducing adverse allergy and asthma outcomes, particularly in homes with pets. ...
The "ASHRAE Position Document on Filtration and Air Cleaning" provides Society members and other stakeholders with information on these technologies and their application. This column answers a few questions about the main positions and statements formulated in the position document (http://tinyurl.com/ashraeiaq).
... The most effective long-term strategy for environmental remediation in pet-sensitized individuals is to remove the pet from the home; however, individuals are often reluctant to remove their pets from the home. HEPA filter use may be beneficial, in petsensitized individuals who are unwilling to remove their pets from the home, because pet allergen may be airborne in these homes [25,26]. ...
In the modern era, the prevalence of asthma and allergies are increasing. It has been speculated that environmental exposures are contributing to this rise. Several studies demonstrate that common indoor allergen exposures exacerbate asthma. Minimizing exposure to allergens and remediating the environment play a critical role in the treatment of asthma and allergies. The most effective environmental control measures are tailored multifaceted interventions which include education, thorough cleaning, using high-efficiency particulate air (HEPA) filters, integrated pest management, and maintenance of these practices.
... For that reason, HEPA devices have been the subject of clinical trials. In a systematic review of HEPA devices, 267 2 studies failed to show decreased symptoms in subjects with dust mite allergy; the other studies were small, had inadequate blinding, lack of measured airborne allergen concentrations, and varied in airevelocity rates relative to room size, location, and occupants. Another review of 10 randomized trials found HEPA filtration to be associated with symptom decreases. ...
... 48,49 High efficiency particulate arrestor (HEPA) air filters may reduce exposure to pet allergens, but clinical impact is uncertain. [50][51][52] Multi-trigger, multi-component approaches more effective ...
Asthma remains the most common chronic condition of childhood. Strong evidence has linked exposure to allergens and other triggers commonly found in homes to allergen sensitization and asthma incidence and morbidity. A growing body of evidence has demonstrated that a home visit strategy that includes an environmental component that addresses multiple triggers through multiple interventions is effective. Such home visits reduce exposure to triggers, decrease symptoms and urgent health-care use, and increase quality of life. To make home visits widely available will require health-care payor reimbursement, government and health plan funding, training and certification of home visitors, and active referrals from health-care providers. However, a strategy based solely on education and behavior change is limited, because it cannot adequately reduce exposures due to adverse housing conditions. Therefore, approaches that address substandard housing are needed. These include remediation of existing housing and construction of new asthma-friendly homes. Most studies of remediation have made relatively narrow and focused improvements, such as insulation, heating, or ventilation. Outcomes have been mixed. Studies of new asthma-friendly homes are in their infancy, with promising pilot data. Further investigation is needed to establish the effectiveness of improving housing. A final strategy is improving housing quality through policy change, such as implementation of healthy housing guidelines for new construction, enhancement and increased enforcement of housing codes, and assuring smoke-free multi-unit homes. The combination of home visits, improved housing construction, and policy change has great potential for reducing the global burden of asthma.
Air filtration is frequently recommended as a component of environmental control measures for patients with allergic respiratory disease. Residential air filtration can be provided by whole house filtration via the home’s heating, ventilation, or air conditioning system, by portable room air cleaners, or a combination of the two. Appliances to filter the sleep breathing zone also have been developed. High-efficiency whole house filtration, high-efficiency particulate air sleep zone air filtration, and high-efficiency particulate air room air cleaners all appear to provide various degrees of benefit. Recent studies of various types of filtration, used alone or as part of more comprehensive environmental control measures, are reviewed.
Objective:
Epidemiologic studies indicate that indoor air pollution is correlated with morbidity caused by allergic diseases. We evaluated the effectiveness of reducing the levels of indoor fine particulate matter < 2.5 micrometer diameter (PM2.5) in Fresno, California using air purifiers on health outcomes in children with asthma and/or allergic rhinitis.
Methods:
The active group (with air purifiers) and the control group consisted of eight houses each. Air purifiers were installed in the living rooms and bedrooms of the subjects in the active group during the entire 12-week study duration. Childhood asthma control test, peak flow rate monitoring, and nasal symptom scores were evaluated at weeks 0, 6, and 12.
Results:
At 12 weeks, the active group showed a trend toward an improvement of childhood asthma control test scores and mean evening peak flow rates, whereas the control group showed deterioration in the same measures. Total and daytime nasal symptoms scores significantly reduced in the active group (p = 0.001 and p = 0.011, respectively). The average indoor PM2.5 concentrations reduced by 43% (7.42 to 4.28 μg/m(3)) in the active group (p = 0.001).
Conclusions:
Intervention with air purifiers reduces indoor PM2.5 levels with significant improvements in nasal symptoms in children with allergic rhinitis in Fresno.
Introduction We breathe about 13 cubic meters of air each day, and many of the particles in the air deposit in our lungs. Hundreds of studies worldwide have documented increases in morbidity and mortality associated with increases in particle levels outdoors. However, people spend almost 90% of their time indoors, and indoor air has its own list of sources that may be as bad or worse than outdoors—for example, cigarette smoke. Therefore much interest lies in developing ways to clean indoor air. One way to improve indoor air quality is to use an air cleaner. Air cleaners have been sold for many years, but it is important to evaluate their effectiveness in reducing pollutants in the home. Therefore Health Canada has sponsored this review of the effectiveness of air cleaners in homes. Although pollutants include gases as well as particles, this review concentrates on particle air cleaners.
The evidence of health benefits of particle filtration in homes and commercial buildings is reviewed. Prior reviews of papers published before 2000 are summarized. The results of 16 more recent intervention studies are compiled and analyzed. Also reviewed are four studies that modeled health benefits of using filtration to reduce indoor exposures to particles from outdoors. Prior reviews generally concluded that particle filtration is, at best, a source of small improvements in allergy and asthma health effects; however, many early studies had weak designs. A majority of recent intervention studies employed strong designs and more of these studies report statistically significant improvements in health symptoms or objective health outcomes, particularly for subjects with allergies or asthma. The percentage improvement in health outcomes is typically modest, e.g., 7% to 25%. Delivery of filtered air to the breathing zone of sleeping allergic or asthmatic persons may be more consistently effective in improving health than room air filtration. Notable are two studies that report statistically significant improvements, with filtration, in markers that predict future adverse coronary events. From modeling, the largest potential benefits of indoor particle filtration may be reductions in morbidity and mortality from reducing indoor exposures to particles from outdoor air. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.
The role of allergen exposure in the etiology of allergic sensitization and asthma is complex. Advice on strategies to avoid domestic allergens remains contentious because trials of interventions aimed to prevent asthma or reduce symptoms have often failed to demonstrate benefits. Asthma management guidelines differ widely in their recommendations, while Web-based information often claims benefits associated with products. In this rostrum we argue that although many factors have a role in both the etiology and the exacerbation of asthma, allergen exposure probably remains an important contributor to the manifestations of the disease. Currently, there is no evidence-based framework for effective domestic allergen avoidance interventions to reduce chronic aeroallergen exposure. The development of an effective approach to allergen avoidance requires a better understanding of (a) the physical nature of chronic aeroallergen exposure and methods for measuring and reducing this, (b) the interaction between allergen exposure and innate immune modulators at different disease stages, and (c) markers enabling the identification of individuals who would benefit from this. The strategic risk of overemphasizing other novel mechanisms and approaches to asthma management is that we will prematurely abandon and fail to improve an existing approach that could have a significant impact on the development, progression, and symptoms of the disease.
Subject matter experts systematically reviewed evidence on the effectiveness of housing interventions that affect health outcomes, primarily asthma, associated with exposure to moisture, mold, and allergens. Three of the 11 interventions reviewed had sufficient evidence for implementation: multifaceted, in-home, tailored interventions for reducing asthma morbidity; integrated pest management to reduce cockroach allergen; and combined elimination of moisture intrusion and leaks and removal of moldy items to reduce mold and respiratory symptoms. Four interventions needed more field evaluation, 1 needed formative research, and 3 either had no evidence of effectiveness or were ineffective. The 3 interventions with sufficient evidence all applied multiple, integrated strategies. This evidence review shows that selected interventions that improve housing conditions will reduce morbidity from asthma and respiratory allergies.
Nighttime allergen exposures are a primary contributor to the development of allergic and asthmatic morbidities. Disease management guidelines recommend the use of environmental control measures to reduce these exposures, but clinically relevant reductions are difficult to achieve because most measures control only 1 allergen source among many in the bedroom environment.
To determine whether a novel localized approach to nighttime allergen avoidance provides effective exposure reductions and clinical benefits.
Thirty-five adults with perennial allergic rhinoconjunctivitis (dog, cat, or dust mite sensitivity) were randomized to receive PureZone, a combination therapy involving localized air filtration and pillow encasement, or placebo in a crossover trial with two 2-week treatment periods separated by a 1-week washout. Nasal and ocular allergy symptoms, quality of life, and breathing zone particulate exposure were assessed. Bedroom allergen dust samples were collected in the sleeping environment.
Reductions (>99.99%) in allergen-sized particulate (> or = 0.3 microm) in the breathing zone led to significant improvements in nocturnal nasal and ocular allergy symptoms (P < .001) and quality of life (P = .02) for the active vs placebo device. Significant nocturnal symptom reductions vs placebo occurred the second night of use and were maintained for the duration of treatment; these reductions improved sleep problems in particular (P = .02). Allergens were detected in 100% of bedrooms, of which 44% had levels that exceeded sensitizing thresholds.
The combination therapy of pillow encasement and localized air filtration provided effective nighttime allergen exposure reductions and clinical benefits without the use of adjunctive therapy.
Twenty percent of the United States population has respiratory allergies. The preferable treatment for allergies is avoidance. Bedrooms offer the best opportunity for allergen avoidance. Most previous studies of air filtration only measured the effect on allergen particle counts, but few have addressed the clinical efficacy. This study measured the effects of a novel laminar flow air filtration device (PureNight) on seasonal ragweed allergies. Seventy-seven percent of the subjects improved significantly on symptom scores, an average of 26% improvement in the morning and 24% in the evening. Daytime sleepiness and quality of life scores also improved significantly in all subjects. Tolerability was excellent. The PureNight device provided significant clinical improvement of allergic symptoms during ragweed hay fever season.
Seventy-five children (ages 4 to 14 years) with perennial rhinitis caused by mold allergy (36 had asthma) were enrolled in an air-cleaner study for 2 years. Symptom scores prior to the study were compared with scores 1 and 2 years after placement of air-cleaners in the bedrooms. Forty-two homes were surveyed for mold count in the air in summer and winter, and the results compared with symptom changes. Improvements were found in quality of sleep (96 vs. 99%), sneezing (80 vs. 90%), scratchy throat (75 vs. 80%), night cough (75 vs. 83%), better mood in the morning (65 vs. 80%), postnasal drip (70 vs. 77%), nasal congestion (70 vs. 72%), night wheezing (70 vs. 83%), and sinus infection (50 vs. 55%). Parents reported a decrease in the use of both over-the-counter (76 vs. 80%) and prescription (43 vs. 48%) drugs. When the weekly symptom score sheets were compared, symptom recurrence rates were found to be clustered in the winter. These symptoms were cough (35%), nasal congestion (35%), sinus infection (32%), and postnasal drip (20%). The average mold counts (expressed as colony-forming-units per cubic meter of air) in the filtered bedrooms, in the unfiltered bedrooms, and outdoors were 310, 425, and 927 in the summer, and 689, 762, and 1213 in the winter, respectively. The higher mold count in the winter may explain the increase in symptoms during that season. We observed a significant improvement in respiratory symptoms for 2 years following the installation of air-cleaners in the bedrooms of 75 children with perennial rhinitis due to mold allergy.
Ninety children (age 4-14 years) with perennial allergic rhinitis were surveyed to determine the effect of an air cleaner in their bedroom on their allergic symptoms and on the quality of their lives. All of the children had symptoms for more than 2 years and were sensitive to multiple mold allergens. Multiple medications had not controlled the symptoms effectively. During the 12 months of the study, the children and their parents kept weekly records of the severity of symptoms. Changes in each child's quality of life were assessed through interviews with the mothers. Comparison of these records with those kept before the use of air cleaners indicated marked improvement on many different fronts when the air cleaners were in use. First, the children slept better, behaved better, and tended to be more cheerful. Second, there was significant improvement in allergic symptoms, such as sneezing, scratchy throat, nasal congestion, coughing, wheezing, infection rate of URI, and postnasal drip. Third, in terms of quality of life, there was a reduction in the number of visits to the emergency room or allergy clinic, the number of workdays missed by the parents, and the number of schooldays missed by the child as a result of the child's allergies. Fourth, the parents' expense for allergy medications decreased dramatically. Finally, the children scored somewhat better on rhinometer tests when the air cleaners were in use than when they were not. We speculate that these improvements may have resulted because the air cleaners removed mold from the air. We conclude that monitoring patients closely while they use the air cleaner provides physicians with a valuable opportunity to teach parents and their children with mold allergy about home environmental control.
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 I. Within 30 min of entering a 30-m3 clean room the cat itself was found to increase airborne Fel d I 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 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 20 h/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 I 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 I compared with approximately 0.5 micrograms/day Fel d I.(ABSTRACT TRUNCATED AT 250 WORDS)
The recent development of a sensitive two-site monoclonal antibody immunoassay for the major cat allergen (Fel d I) has made it possible to make accurate measurements of airborne cat allergen using low volume samplers that do not disturb the room. Houses with cats had from 2 to 20 ng Fel d I/m3 air compared with less than 0.2 ng/m3 in houses without cats. Using a cascade impactor and a multistage liquid impinger, the particle size distribution of airborne Fel d I in nine houses was 75% on particle greater than or equal to 5 microns in diameter and 25% (range, 10 to 62%) on particles less than or equal to 2.5 microns. In a cat vivarium with 12 cats, the air contained 40 ng Fel d I/m3, but less than 2% was detected on particles less than or equal to 2.5 microns. The air exchange rate in the vivarium (approximately 15 changes/h) appears to be the major difference from domestic houses (less than 0.5 changes/h). Repeated studies in one house confirmed a very high proportion (approximately 60%) of Fel d I on small particles. During domestic cleaning, the levels of small particle allergen in this house approached those produced by a nebulizer for bronchial provocation, i.e., 40 ng/m3. These results show unequivocally that significant airborne Fel d I is associated with small particles, which remain airborne for long periods. These findings are strikingly different from previous results obtained with airborne dust mite allergen. The results provide an explanation for the distinctive rapid onset of asthma or rhinitis in patients allergic to cats and a basis for designing a policy to reduce airborne allergen in houses with cats.
Manufacturers of ionisers claim many benefits from the use of their devices, including the relief of asthma. Particles removed from the air are likely to include airborne allergens, so ionisers may achieve an effect by reducing the allergen load.
The effect of ionisers on airborne concentrations of house dust mite allergen Der p I was investigated in a double blind, crossover, placebo controlled trial in the homes of 20 children with allergic asthma. Subjects recorded their peak expiratory flow rate (PEFR) twice daily and completed a daily symptom score and treatment schedule on a diary card for two six week periods, one with an active ioniser and the other with a placed ioniser (randomly allocated) used in the living room and the bedroom.
Airborne Der p I concentrations fell significantly during the active period compared with the placebo period, but there was no significant change in PEFR, symptom scores, or treatment usage. There was an increase in night time cough which almost reached significance during the active period.
This study indicates that the use of ionisers cannot be recommended in the homes of asthmatic subjects to improve their symptoms. The significant reduction of airborne allergen concentrations may be of use as part of a multidevice allergen avoidance regimen, but the increase in night time cough requires further study.
Recommendations for allergen avoidance or allergen reduction measures play an important part in the treatment of allergic asthmatic patients. The purpose of this study was to test recently developed air-cleaners with respect to their capacity to capture airborne allergen particles and to improve clinical parameters of asthmatic patients sensitized to aeroallergens. Forty five allergic asthmatic patients were studied in a double-blind procedure for 6 months. The patients were divided into three groups of 15 patients. In Group 1, the intervention consisted of the application of active air-cleaners in living-rooms and bedrooms. In Group 2, placebo air-cleaners were used in combination with allergen-impermeable mattress covers. In Group 3, the same intervention was performed as in Group 2 but with active air-cleaners. Allergen levels in mattress and floor dust were measured before, and 3 and 6 months after the interventions. After 6 months, the air-cleaners were dismantled and the filters were analysed for the amount of dust collected and allergen content. Immunological and lung function parameters were measured before, and 3 and 6 months after the interventions. Considerable amounts of airborne dust and allergenic particles were captured in the filters of the air-cleaners. Up to the 18.9 g of dust, 4,513 ng of house dust mite allergen, Der p 1, and 50,000 mU of cat allergen, Fel d 1, (in houses with cats) were collected by air-cleaners in living-rooms. Only in Group 3 (in which both active air-cleaners and mattress covers were used) was a small (less than 1 doubling dose) but statistically significant improvement of provocative concentration of histamine causing a 20% fall in forced expiratory volume in one second (PC20) observed (from 5.96 to 9.02 mg x mL(-1)). The amount of dust and house dust mite allergen collected in the filters was significantly correlated with an improvement of peak flow variation. In combination with other allergen avoidance measures, the examined air-cleaners can contribute to diminished allergen exposure and improvement of airway hyperresponsiveness in asthmatic patients.
Sensitisation to cat allergen (Fel d 1) is an important risk factor for asthma in the UK. A study was undertaken to investigate the distribution of cat allergen in British homes, the aerodynamic characteristics and particle size distribution of airborne Fel d 1, and the method of removing it.
Dust was collected from 50 homes with a cat and from 50 homes without a cat, and airborne levels of Fel d 1 were measured in 50 homes with a cat and 75 homes without a cat. Particle size distribution was determined using an Andersen sampler (8 hours/day) in 10 homes with cats. This was repeated on five separate days in a house with four cats, and then one, two, four, seven, and 14 days after the cats were removed from the living room area. The effect of high efficiency particulate air (HEPA) cleaner on airborne levels of Fel d 1 was investigated in seven homes with cats. Samples were collected on two separate days from two rooms of each house concurrently, one of which contained the cat, one day with the HEPA cleaner on and the other day as a control. Three one hourly samples were collected over a nine hour period (baseline, 4-5 hours, 8-9 hours) using a high volume dust sampler (air flow rate 60 l/min) and the air sample was collected onto a microglass fibre filter (pore size 0.3 micron).
Fel d 1 concentrations were much lower in houses without a cat than in those with a cat (260-fold difference (95% CI 167 to 590) in living room carpets: geometric mean (GM) 0.9 microgram/g (range 0.06-33.93) versus 237 micrograms/g (range 2.8-3000); 314-fold difference (95% CI 167 to 590) in upholstered furniture: 1.21 micrograms/g (range 0.06-61.9) versus 380 micrograms/g (range 7.1-6000); 228-fold difference (95% CI 109 to 478) in bedroom carpets: 0.24 microgram/g (range 0.06-2.24) versus 55 micrograms/g (range 0.06-2304); and 215-fold difference (95% CI 101 to 456) in mattresses: 0.2 microgram/g (range 0.06-2.3) versus 55 micrograms/g (range 0.06-3400). Airborne levels of Fel d 1 were detected in all houses with cats, and the levels varied greatly between the homes (range 0.7-38 ng/m3). Low concentrations of airborne Fel d 1 (range 0.24-1.78 ng/m3) were found in 22 of 75 homes without a cat. Although airborne Fel d 1 was mostly associated with large particles (> 9 microns, approximately 49% of the allergen recovered), small particles (< 4.7 microns) comprised approximately 23% of the total airborne allergen. Total airborne Fel d 1 was reduced by 61.7% two days after removal of the cat but this was due predominantly to the decrease in larger particles (> 4.8 microns) which fell to 13% of their baseline level. Fel d 1 levels associated with small particles (< 4.8 microns) remained largely unchanged on days 1, 2 and 4 and then slowly decreased to 33% of the baseline levels at day 14. With HEPA cleaner a significant reduction in airborne Fel d 1 was observed compared with the control sampling (GM 5.04-0.88 ng/m3 versus 3.79-1.56 ng/m3 at baseline and 8 hours, active versus control group; p = 0.008).
Airborne Fel d 1 was detectable in undisturbed conditions in all homes with cats and in almost a third of homes without cats. In houses with cats a significant proportion (23%) of airborne Fel d 1 was associated with small particles (< 4.7 microns diameter). Removal of the cat from the living room and bedroom areas of the home and the use of HEPA air cleaner reduced airborne levels of cat allergen in homes with cats, but the reduction following cat removal was not evenly spread across the particle size range.
A new, portable laminar air-flow filter (Enviracaire) was tested on 13 asthmatic children, using a double-blind single crossover study. There was a statistical improvement in symptom scores during filter use; however, peak flows did not improve significantly. The authors feel this method of avoiding indoor airborne irritants is useful and warrants further study.
The efficacy of an air-cleaning device equipped with a high efficiency particulate air (HEPA) filter (without further avoidance measures) was studied in patients allergic to house dust mite. The effects of the air-cleaner on indoor Dermatophagoides sp. levels, symptom score and bronchial hyperresponsiveness in nine mite-allergic patients were assessed using a cross-over controlled study. No significant effect was demonstrated on indoor Dermatophagoides sp. levels when comparing the period of air-cleaner activity (2 months) with the control period (2 months). The Dermatophagoides sp. levels in the houses studied were lower than the risk level for asthmatic attacks, making it difficult to assess any effect on asthma; however, neither bronchial hyperresponsiveness nor rhinitis symptom score were changed by air-cleaner activity. During the trial period, however the mean level of Dermatophagoides sp. allergen in the houses changed spontaneously from 4.4 micrograms/g (mean level in the first 2 trial months) to 1.75 micrograms/g of dust (second 2 months) (P less than 0.05). Owing to this change, the mean rhinitis symptom score also decreased (P less than 0.05), even if no significant correlation was demonstrated (r = 0.4 P = 0.089). HEPA filter air-cleaners appear insufficient as substitutes for standard avoidance measures in mite allergic patients.
This study was designed to assess the effectiveness of a high-efficiency particulate air (HEPA) filter in alleviating allergic respiratory symptoms. Thirty-two patients were studied who had symptomatic perennial rhinitis and/or asthma during the fall and winter months and had a positive skin test with house dust or house dust--mite extract. An ENVIRACAIRE room air cleaner was placed in the bedroom for 8 weeks. In a random manner, the active filter was used for 4 weeks and a blank filter for 4 weeks. There was an average 70% reduction in the particulate matter greater than or equal to 0.3 micron with the HEPA filter. In a double-blind design, results were assessed by analysis of the patients' symptom/medication scores and subjective evaluation. For the total study, there was no difference in the total symptom/medication scores or individual symptom scores during the placebo and active-filter periods. Analysis of the last 2 weeks of each filter period in which respiratory infection was absent demonstrated definite differences in total and individual symptoms, suggesting active-filter benefit. Patients' subjective responses also suggested benefit from the filter. The overall impression is that the HEPA filter can reduce allergic respiratory symptoms.
Thirteen house dust mite-allergic young asthmatics were entered into a double-blind, crossover clinical trial to compare "in use" with "non-use" of a laminar flow air cleaner bed attachment. The study design encouraged maintenance of symptom control by adjustment of the dose of medications used. There was a significant reduction in the amount of medications required by the patients during the trial period that the air cleaner was in use. Histamine airway responsiveness was significantly decreased for a group of eight of the subjects tested at the end of a 3-month open trial.
Patients with asthma may develop acute symptoms after exposure to domestic or laboratory animal allergens; however, they are usually not aware of a direct relationship between their acute attacks and exposure to pollen or dust mite allergens. The present experiments were designed to study whether the differences in symptoms could be explained by differences in the number or size of particles carrying airborne allergens. Airborne particles were collected with a filter or on the stages of a cascade impactor, and allergens were measured by use of inhibition radioimmunoassays. In rat rooms and during disturbance of rat litter, a large proportion of rat urinary allergen (45.9%) was collected on the second stage of the impactor (mean size approximately 7 microns diameter). When sampled 15 to 35 minutes after disturbance, 16% of these medium-sized particles were still airborne. By contrast, during disturbance of house dust, a significantly larger proportion of dust mite, antigen P1 (80.6 +/- 11.8%; p less than 0.001) was collected on the first stage of the impactor, and in keeping with the apparent size of these particles (diameter greater than 10 microns), very little of this allergen (less than 4%) was still airborne when sampled 15 to 35 minutes after disturbance. With nebulized diluted rat urine, approximately 75% of the allergen was collected on the fourth and final stages of the cascade impactor in keeping with the expected size, 0.5 to 3 microns in diameter. These results demonstrate that natural exposure to both allergens is strikingly different from the conditions used for bronchial provocation.(ABSTRACT TRUNCATED AT 250 WORDS)
In a double blind study of 18 symptomatic asthmatic children, a high efficiency filtering device was added to standard environmental control. The further purification of respired air resulted in significant reduction of allergic symptoms and medications necessary to control symptoms.
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.
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.
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.
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 2.63-329) 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).
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.
Exposure to cat and dog allergens is very common in the Western World and is a serious cause of asthma in sensitized subjects.
We sought to study the clinical effects of air cleaners in living rooms and bedrooms of asthmatic children sensitized to cat or dog allergens.
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.
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.
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.
To further characterize airborne cat allergen and a newly established cat challenge facility, airborne Fel d I levels and particle size distributions were studied in both the cat challenge room and home environments under different conditions of ventilation and physical activity. In the cat room, there has been a dramatic and continued rise in the concentration of airborne Fel d I since the room was established. No differences in total airborne Fel d I levels or particle size distribution were detected under widely differing rates of ventilation (40 air changes per hour vs 8 ac/hr vs < 1 ac/hr). Likewise, altering ventilation had little effect on the clearance of airborne antigen after disturbance. Significant increases in allergen levels were detected, however, after simply allowing the cats to leave their holding cage and move about the room. Fel d I levels in homes ranged from 2-468.5 ng/m3, similar to the levels seen in the cat room without disturbance. Fel d I particle size distribution was very consistent in both homes and the cat room with the majority of airborne Fel d I being detected on particles > 17 microm. Although very little allergen (< 15%) was detected on particles < 4 microm, this important fraction was present under all conditions. We conclude that airborne cat allergen resides primarily on relatively large particles, that a small but consistent fraction is found on very small particles, and that neither allergen levels or particles size distribution are significantly influenced by ventilation.
Clinical effects of air cleaners in homes of children sensitized to pet allergens This study is important in that it is one of the few controlled trials of air cleaner use in pediatric asthma. It is also the study that provides the most convincing data on the potential benefits of air cleaners
- Van
- S Heide
- Wmc Aalderen
- Kauffman
- Hf
Airborne concentrations and particle size distribution of allergen derived from domestic cats (Felis domesticus)
- Luczynska
- Cm
- Y Li
- Md Chapman
- Platts-Mills
- Tae
Luczynska CM, Li Y, Chapman MD, Platts-Mills TAE: Airborne concentrations and particle size distribution of allergen derived from domestic cats (Felis domesticus). Am Rev Respir Dis 1990, 141:361–367.
Clinical effects of air cleaners in homes of children sensitized to pet allergens This study is important in that it is one of the few controlled trials of air cleaner use in pediatric asthma
- S Heide Van der
Airborne concentrations and particle size distribution of allergen derived from domestic cats (Felis domesticus)
- C M Luczynska
- Y Li
- M D Chapman
- Tae Platts-Mills
- CM Luczynska
This study is important in that it is one of the few controlled trials of air cleaner use in pediatric asthma
- Heide S Van Der
- Wmc Van Aalderen
- H F Kauffman
- S Van der Heide