Indoor Allergens Assessing and Controlling Adverse Health Effects (1993) / Chapter Skim
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Executive Summary
Executive Summary
Pages 1-33
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Methods for detecting and characterizing specific allergic diseases include taking a thorough medical history and performing skin tests, in vitro antibody tests, and pulmonary function tests. Environmental testing and exposure assessment can identify contaminants and their sources, environmental exposure media, routes of entry into the body, intensity and frequency of contact, and spatial and temporal concentration patterns.
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to identify airborne biological and chemical agents found indoors that can be directly linked to allergic diseases; (2) to assess .
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; according to the specific immunologic reactants (such as the types of antibodies or immune system cells involved in the reaction) ; or on the basis of the resulting disease (such as allergic asthma or hypersensitivity pneumonitis)
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Another illustration of the process of developing allergic disease is presented in Figure 3. This figure shows the series of steps, beginning with the sensitization of a genetically predisposed or susceptible individual, and the potential interaction with other, nonallergenic agents (e.g., environmental tobacco smoke)
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Exposure to allergen is understood to be a major factor at each stage of the pathogenesis of these diseases. MAGNITUDE OF THE PROBLEM The most common allergic diseases caused by indoor allergens are allergic rhinitis, sinusitis, asthma, and allergic skin diseases (dermatitis)
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becoming sensitized to indoor allergens, the risk of developing an allergic disease, and the severity of the allergic disease. · Population-based and case-control studies suggest that indoor allergens are a major reason for trips to hospital emergency rooms.
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Other allergic diseases related to indoor exposures, such as allergic bronchopulmonary aspergillosis and hypersensitivity pneumonitis, occur less frequently than allergic rhinitis and asthma, but are often severe and difficult to control. A role for indoor allergens has also been suggested in chronic sinusitis and bronchitis, sick building syndrome, and other nonspecific syndromes, as well as in acute respiratory illness.
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Source: NHLBI, 1991. Work and school absenteeism as a result of allergic reactions of the upper airway contributes to the economic burden posed by indoor allergens.
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The allergens produced by these organisms become airborne and can cause the allergic diseases mentioned previously, such as hay fever, asthma, and hypersensitivity pneumonitis. The dust mite, a microscopic organism that lives primarily in carpeting and on mattresses and upholstery, produces several of the most common residential allergens.
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MECHANISMS OF IMMUNE FUNCTION The immunologic nature of allergic reactions was recognized early in this century, but many of the specific types of antibodies and cellular mechanisms involved in such reactions have only recently been defined. Research on the immune mechanisms of allergic disease has led to the hope that the immune responses that occur in allergic diseases can be interrupted at the molecular level.
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Thus, although confirmation of a diagnosis of allergy generally requires an immunologic (laboratory) test to help identify a specific allergenic agent, an immunologic response is not sufficient to diagnose allergic disease; it means only that a prior sensitizing exposure has occurred.
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Ideally, minimal standards for quality control should be devised for labs reporting results of tests to detect specific immunologic responses to indoor allergens. Pulmonary Function Tests Diseases such as asthma and hypersensitivity pneumonitis are characterized by decrements in lung function that vary over time.
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In an example using published data on dust mite allergy, this committee reports a positive relationship between cumulative exposure to dust mite allergen and the risk of allergic sensitization (see Figure 81. This is a finding that has long been suspected to exist, but has not been previously demonstrated.
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. The improved design, maintenance, and operation of residences and other buildings should reduce the incidence, prevalence, and severity of allergic disease.
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Meanwhile, efforts to improve what is already known about preventing and controlling allergic diseases should continue. This knowledge should be disseminated to health care providers, allergy patients, and the public at large.
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, fitted carpets, and cool-wash detergents which have led to water temperatures for washing bedding that do not kill dust mites. Once identified, reducing exposure to allergenic "trigger factors" has been a standard part of the treatment of allergic disease for many years.
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Recommendation: Encourage the development and use of improved standardized methods for performing and interpreting skin tests. Pulmonary Function Tests There are simple, reliable measures of lung function that may be used for studying diseases caused by indoor allergens.
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ASSESSING EXPOSURE AND RISK Methods for determining the effects of indoor allergens can be divided into two general categories: patient testing and environmental testing. Data from both kinds of testing can be useful to the physician in directing the treatment, control, and prevention of allergic disease.
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Considering that a large percentage of hospital admissions for asthma can be prevented by educating physicians and patients in the proper control measures, the need for emphasis on education becomes obvious. By disseminating information to patients, to health care providers, and to building design, construction and operations professionals, prevention of diseases associated with indoor allergens becomes not only realistic, but may offer a cost-effective means of reducing morbidity.
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Recommendation: Incorporate the diagnosis and management of allergic diseases in the curricula and training materials for medical school students, residents in primary care practice, and subspecialists
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Recommendation: Encourage scientific and medical societies with expertise in allergy, pulmonary medicine, public health, and occupational and environmental medicine to continue to assess and promote the development of prevention strategies for allergic disease. Engineers, Architects, and Building Maintenance Personnel Concerns about the design and operation of heating, ventilation, and air conditioning systems have focussed traditionally on the comfort of the building occupants and the efficiency of the operation of the equipment.
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Better data regarding the incidence, prevalence, attributable fraction, and cost of allergic diseases are essential to the development and implementation of effective programs of prevention and control. Accurate determinations of the magnitude and dimensions of sensitization and disease caused by regional and local indoor allergens would be useful in this regard.
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The relationship between exposure, sensitization, and disease, and the potential for a threshold level of exposure below which the risk of sensitization is reduced, is of critical importance in the prevention and control of allergic disease. Epidemiological data would be useful in determining these relationships and in developing and evaluating public health and medical intervention strategies.
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devices advertised as reducing indoor allergen concentrations. More specifically, test the effectiveness of allergen avoidance protocols on the management of allergic asthma and other allergic diseases using protocols that have been demonstrated to reduce exposure by 90 percent or more.
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Research Agenda Item: Investigate the potential role of mammalian- and avian-allergen-contaminated ventilation systems in the development of allergic disease among inhabitants of apartments, offices, and other large buildings.
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Little data is available on the distribution of airborne fungal products, dynamics of human exposure, nature of the allergens, factors influencing the quality of skin test and immunotherapy materials, and the nature of fungus-related allergic disease. Research Agenda Item: Initiate and conduct studies to determine the relative etiologic importance, geographic distribution, and concentrations of airborne fungus material associated with indoor allergy.
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A better understanding of these differences will assist in the formulation of improved measures of prevention and treatment. Research Agenda Item: Determine the types of allergic diseases caused by reactive allergenic chemicals, their prevalence rates, and the mechanisms responsible for the resulting airway reactions.
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workers are exposed to such chemicals that can form haptens with airway proteins and induce allergic diseases. The goal of reducing the incidence and severity of allergic disease caused by chemical exposure is achievable, although it may not be possible to prevent all such disease.
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MEDICAL TESTING METHODS Medical History and Diagnosi In spite of universal agreement on the primary importance of a patient's allergy history very little space in medical textbooks is devoted to the topic, and no standard exists for collecting appropriate information. A standardized, validated allergy-history questionnaire would be useful in both clinical and research settings.
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Future studies in the development of in vitro diagnostic tests should include the following: Research Agenda Item: Identify selected allergens of potential re search usefulness, and prepare pure reference standards for the development of immunoassays, including those that can be used in laree scale epidemiological studies. -r ~ Research Agenda Item: Develop and assess immunoassays for new allergens, including low molecular weight allergenic chemicals, that can be used for research and for the diagnosis of allergic disease.
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The data can be described by a linear model and indicates that there is a positive relationship between cumulative exposure to dust mite allergen and the risk of sensitization. Some residual sensitization (i.e., approximately 10 percent in this example)
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Research Agenda Item: Develop standardized test procedures for rating the effectiveness of air cleaning devices and other methodologies for removal of known size classes of particles containing allergens. The tests should address the capability of the device or methodology in removing airborne particulates from entire rooms or zones of buildings.
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Research Agenda Item: Evaluate the role of duct cleaning in controlling allergic diseases. As described throughout this report, ambient relative humidity is often considered a major controlling factor for indoor allergens.
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