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Environmental and occupational allergies

2010; Elsevier BV; Volume: 125; Issue: 2 Linguagem: Inglês

10.1016/j.jaci.2009.10.073

1097-6825

David B. Peden, Charles E. Reed,

Indoor Air Quality and Microbial Exposure

Airborne allergens are the major cause of allergic rhinitis and asthma. Daily exposure comes from indoor sources, chiefly at home but occasionally at schools or offices. Seasonal exposure to outdoor allergens, pollens, and molds is another important source. Exposure to unusual substances at work causes occupational asthma, accounting for about 5% of asthma in adults. Indoor and outdoor air pollutants trigger airway inflammation and increase the severity of asthma. Diesel exhaust particles increase the production of IgE antibodies. Identification and reduction of exposure to allergens is a very important part of the management of respiratory allergic diseases. The first section of this chapter discusses domestic allergens, arthropods (mites and cockroaches), molds, and mammals (pets and mice). Indoor humidity and water damage are important factors in the production of mite and mold allergens, and discarded human food items are important sources of proliferation of cockroaches and mice. Means of identifying and reducing exposure are presented. The second section discusses outdoor allergens: pollens and molds. The particular plants or molds and the amount of exposure to these allergens is determined by the local climate, and local pollen and mold counts are available to determine the time and amount of exposure. Climate change is already having an important effect on the distribution and amount of outdoor allergens. The third section discusses indoor and outdoor air pollution and methods that individuals can take to reduce indoor pollution in addition to eliminating cigarette smoking. The fourth section discusses the diagnosis and management of occupational asthma. Airborne allergens are the major cause of allergic rhinitis and asthma. Daily exposure comes from indoor sources, chiefly at home but occasionally at schools or offices. Seasonal exposure to outdoor allergens, pollens, and molds is another important source. Exposure to unusual substances at work causes occupational asthma, accounting for about 5% of asthma in adults. Indoor and outdoor air pollutants trigger airway inflammation and increase the severity of asthma. Diesel exhaust particles increase the production of IgE antibodies. Identification and reduction of exposure to allergens is a very important part of the management of respiratory allergic diseases. The first section of this chapter discusses domestic allergens, arthropods (mites and cockroaches), molds, and mammals (pets and mice). Indoor humidity and water damage are important factors in the production of mite and mold allergens, and discarded human food items are important sources of proliferation of cockroaches and mice. Means of identifying and reducing exposure are presented. The second section discusses outdoor allergens: pollens and molds. The particular plants or molds and the amount of exposure to these allergens is determined by the local climate, and local pollen and mold counts are available to determine the time and amount of exposure. Climate change is already having an important effect on the distribution and amount of outdoor allergens. The third section discusses indoor and outdoor air pollution and methods that individuals can take to reduce indoor pollution in addition to eliminating cigarette smoking. The fourth section discusses the diagnosis and management of occupational asthma. Two key factors influence the development and severity of allergic disease: host factors and environmental factors. Environmental factors include the specific allergens that are the targets of the IgE-mediated immune response, those elements of the environment that influence the presence of those allergens, and indoor and outdoor air pollutants. Also, environmental stimulants of innate immunity influence the development of allergic responses. Although pharmacologic treatments focus on host factors, interventions directed at environmental factors are critical for optimal management of allergic disease, as well as its prevention. Environments can be defined as domestic, outdoors, and occupational, and this chapter will focus on the identification of environmental exposures and methods of intervention for their control. The primary indoor allergens that contribute to allergic disease include arthropod allergens, mammalian allergens (from either pets or pests), and fungal allergens.1Gold D.R. Environmental tobacco smoke, indoor allergens, and childhood asthma.Environ Health Perspect. 2000; 108: 643-651PubMed Google Scholar, 2Gruchalla R.S. Pongracic J. Plaut M. Evans III, R. Visness C.M. Walter M. et al.Inner City Asthma Study: relationships among sensitivity, allergen exposure, and asthma morbidity.J Allergy Clin Immunol. 2005; 115: 478-485Abstract Full Text Full Text PDF PubMed Scopus (189) Google Scholar, 3Platts-Mills T.A. Allergens and asthma.Allergy Proc. 1990; 11: 269-271Crossref PubMed Google Scholar, 4Platts-Mills T.A. Ward Jr., G.W. Sporik R. Gelber L.E. Chapman M.D. Heymann P.W. Epidemiology of the relationship between exposure to indoor allergens and asthma.Int Arch Allergy Appl Immunol. 1991; 94: 339-345Crossref PubMed Google Scholar, 5Platts-Mills T.A. Sporik R.B. Chapman M.D. Heymann P.W. The role of domestic allergens.Ciba Found Symp. 1997; 206: 173-185PubMed Google Scholar Additionally, indoor pollutants can also influence host response to allergens and should be considered when developing environmental interventions.6Sharma H.P. Hansel N.N. Matsui E. Diette G.B. Eggleston P. Breysse P. Indoor environmental influences on children's asthma.Pediatr Clin North Am. 2007; 54 (ix): 103-120Abstract Full Text Full Text PDF PubMed Scopus (31) Google Scholar Seasonal outdoor allergens can also play a role in the indoor environment when they penetrate into the indoor setting.6Sharma H.P. Hansel N.N. Matsui E. Diette G.B. Eggleston P. Breysse P. Indoor environmental influences on children's asthma.Pediatr Clin North Am. 2007; 54 (ix): 103-120Abstract Full Text Full Text PDF PubMed Scopus (31) Google Scholar There is overwhelming evidence that indoor domestic allergens play a key role in allergic disease. The primary arthropod allergens associated with allergic disease are house dust mites and cockroaches. The 2 primary species of house dust mite associated with asthma are Dermatophagoides farinae and Dermatophagoides pteronyssinus. The prevalence of IgE sensitization to mites varies with the local environment; arid environments are associated with low-level sensitization (5%), whereas up to 60% of the population can be sensitized in humid locales. Exposure to mite allergens has been associated not only with the severity of allergic disease but also with disease pathogenesis.3Platts-Mills T.A. Allergens and asthma.Allergy Proc. 1990; 11: 269-271Crossref PubMed Google Scholar, 4Platts-Mills T.A. Ward Jr., G.W. Sporik R. Gelber L.E. Chapman M.D. Heymann P.W. Epidemiology of the relationship between exposure to indoor allergens and asthma.Int Arch Allergy Appl Immunol. 1991; 94: 339-345Crossref PubMed Google Scholar, 6Sharma H.P. Hansel N.N. Matsui E. Diette G.B. Eggleston P. Breysse P. Indoor environmental influences on children's asthma.Pediatr Clin North Am. 2007; 54 (ix): 103-120Abstract Full Text Full Text PDF PubMed Scopus (31) Google Scholar, 7Matsui E.C. Hansel N.N. McCormack M.C. Rusher R. Breysse P.N. Diette G.B. Asthma in the inner city and the indoor environment.Immunol Allergy Clin North Am. 2008; 28 (x): 665-686Abstract Full Text Full Text PDF PubMed Scopus (19) Google Scholar, 8Sporik R. Squillace S.P. Ingram J.M. Rakes G. Honsinger R.W. Platts-Mills T.A. Mite, cat, and cockroach exposure, allergen sensitisation, and asthma in children: a case-control study of three schools.Thorax. 1999; 54: 675-680Crossref PubMed Google Scholar These microscopic arachnids do not bite humans or other animals but feed on human and animal dander and are found in bedding, upholstery, and carpeting. House dust mites require humid environments because they directly absorb water from the air, with critical relative humidity ranging from 55% to 75% depending on the ambient temperature. There are 2 major groups of mite allergens, with group 1 being derived from proteins found in the mite gut and group 2 being primarily male reproductive glycoproteins. A major source of mite allergens is mite fecal pellets. These allergens are found on particles that range from 10 to 20 μm in size, which means they tend to settle on surfaces and are not suspended in ambient air.9Diette G.B. McCormack M.C. Hansel N.N. Breysse P.N. Matsui E.C. Environmental issues in managing asthma.Respir Care. 2008; 53: 602-615PubMed Google Scholar, 10Diette G.B. Hansel N.N. Buckley T.J. Curtin-Brosnan J. Eggleston P.A. Matsui E.C. et al.Home indoor pollutant exposures among inner-city children with and without asthma.Environ Health Perspect. 2007; 115: 1665-1669Crossref PubMed Scopus (46) Google Scholar Cockroaches represent another significant source of allergens, with the German cockroach (Blatella germanica) and the American cockroach (Periplaneta americana) being the most frequently encountered species in American homes. Cockroach allergy plays a critical role in asthma pathogenesis in the inner city, with the degree of sensitization being linked to the likelihood of requiring urgent or emergency treatment for asthma in urban populations. It has been reported that up 40% of urban children and 20% of suburban children are sensitized to cockroach allergens.9Diette G.B. McCormack M.C. Hansel N.N. Breysse P.N. Matsui E.C. Environmental issues in managing asthma.Respir Care. 2008; 53: 602-615PubMed Google Scholar, 10Diette G.B. Hansel N.N. Buckley T.J. Curtin-Brosnan J. Eggleston P.A. Matsui E.C. et al.Home indoor pollutant exposures among inner-city children with and without asthma.Environ Health Perspect. 2007; 115: 1665-1669Crossref PubMed Scopus (46) Google Scholar Cockroaches tend to feed on discarded human food items. Thus they are attracted to locations in which such materials are readily available. Although they are found in single-family homes, they are more successful in townhomes and multifamily dwellings, which have a higher concentration of persons and, consequently, more discarded food. Cockroaches live in confined spaces, often in walls and between floors in large buildings, and are more active at night.11Matsui E.C. Wood R.A. Rand C. Kanchanaraksa S. Swartz L. Curtin-Brosnan J. et al.Cockroach allergen exposure and sensitization in suburban middle-class children with asthma.J Allergy Clin Immunol. 2003; 112: 87-92Abstract Full Text Full Text PDF PubMed Scopus (58) Google Scholar Cockroach allergens derive from the bodies and feces of these insects. Like mite allergens, cockroach allergens tend to be found on larger particles (10-40 μm in diameter) and thus are more likely to be found in settled house dust rather than on suspended particles in ambient air. Cockroach allergen can be found in high concentrations on floors, carpets, counters, and other flat surfaces, especially in rooms that contain discarded or stored food. Cockroach allergens have also been reported in bedding, although this might be from passive transport of allergens from floor dust to the bed by persons living in cockroach-infested locations.9Diette G.B. McCormack M.C. Hansel N.N. Breysse P.N. Matsui E.C. Environmental issues in managing asthma.Respir Care. 2008; 53: 602-615PubMed Google Scholar, 11Matsui E.C. Wood R.A. Rand C. Kanchanaraksa S. Swartz L. Curtin-Brosnan J. et al.Cockroach allergen exposure and sensitization in suburban middle-class children with asthma.J Allergy Clin Immunol. 2003; 112: 87-92Abstract Full Text Full Text PDF PubMed Scopus (58) Google Scholar Rodent allergens are also important allergens in the inner city, with mice being more common in domestic settings than rats because rats tend to stay outdoors. Mouse allergen exposure has been associated with decreased asthma control in inner-city residents. Mouse allergen has also been found in suburban settings and single-family homes but at levels that are typically 100- to 1,000-fold less than those reported in inner-city dwellings. Mouse allergens are present in urine and are associated with pheromones and the mating behavior of these animals. Rodent urine is easily aerosolized, and thus rodent allergens can be found in smaller particles (<10 μm in diameter), which can be suspended in ambient air. Like cockroaches, feral mice tend to nest in small hidden spaces and are active primarily at night. Thus it is relatively rare to encounter these animals during the day. These animals are also attracted to discarded human food materials, and thus mouse allergen might be found in greater concentrations in areas where garbage is stored before disposal. In the event that mice are kept as pets, exposure to mouse allergen is similar to that of animal handlers and is principally in the bedding of the cages in which the animals are kept.7Matsui E.C. Hansel N.N. McCormack M.C. Rusher R. Breysse P.N. Diette G.B. Asthma in the inner city and the indoor environment.Immunol Allergy Clin North Am. 2008; 28 (x): 665-686Abstract Full Text Full Text PDF PubMed Scopus (19) Google Scholar, 12Chew G.L. Perzanowski M.S. Miller R.L. Correa J.C. Hoepner L.A. Jusino C.M. et al.Distribution and determinants of mouse allergen exposure in low-income New York City apartments.Environ Health Perspect. 2003; 111: 1348-1351Crossref PubMed Google Scholar, 13Curtin-Brosnan J. Matsui E.C. Breysse P. McCormack M.C. Hansel N.N. Tonorezos E.S. et al.Parent report of pests and pets and indoor allergen levels in inner-city homes.Ann Allergy Asthma Immunol. 2008; 101: 517-523Abstract Full Text Full Text PDF PubMed Google Scholar, 14Matsui E.C. Simons E. Rand C. Butz A. 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The relationship of mouse allergen exposure to mouse sensitization and asthma morbidity in inner-city children with asthma.J Allergy Clin Immunol. 2000; 106: 1075-1080Abstract Full Text Full Text PDF PubMed Scopus (130) Google Scholar Mammalian pets are also a source of allergens, with dogs and cats being by far the most common pets in the United States. Common allergens derived from dogs and cats include Can f 1 and Fel d 1 and can be derived from saliva, dander, or other secretions. Like rodents, dog and cat allergens are found in small aerosolized particles (<10 μm in diameter) and can be found suspended in ambient air.4Platts-Mills T.A. Ward Jr., G.W. Sporik R. Gelber L.E. Chapman M.D. Heymann P.W. Epidemiology of the relationship between exposure to indoor allergens and asthma.Int Arch Allergy Appl Immunol. 1991; 94: 339-345Crossref PubMed Google Scholar, 18Celedon J.C. Litonjua A.A. Ryan L. Platts-Mills T. Weiss S.T. Gold D.R. Exposure to cat allergen, maternal history of asthma, and wheezing in first 5 years of life.Lancet. 2002; 360: 781-782Abstract Full Text Full Text PDF PubMed Scopus (145) Google Scholar, 19Erwin E.A. Woodfolk J.A. Custis N. Platts-Mills T.A. Animal danders.Immunol Allergy Clin North Am. 2003; 23: 469-481Abstract Full Text Full Text PDF PubMed Scopus (15) Google Scholar, 20Leaderer B.P. Belanger K. Triche E. Holford T. Gold D.R. Kim Y. et al.Dust mite, cockroach, cat, and dog allergen concentrations in homes of asthmatic children in the northeastern United States: impact of socioeconomic factors and population density.Environ Health Perspect. 2002; 110: 419-425Crossref PubMed Google Scholar, 21Perzanowski M.S. Ronmark E. Platts-Mills T.A. Lundback B. Effect of cat and dog ownership on sensitization and development of asthma among preteenage children.Am J Respir Crit Care Med. 2002; 166: 696-702Crossref PubMed Scopus (177) Google Scholar These allergens, especially those from cats, can be carried to other locations on the clothing of persons who own cats. It has also been reported that dog and cat allergens are found in house dust of homes with and without animals. Thus community exposure to these and probably many other domestic allergens likely contributes to exposure to these allergens outside of the home.7Matsui E.C. Hansel N.N. McCormack M.C. Rusher R. Breysse P.N. Diette G.B. Asthma in the inner city and the indoor environment.Immunol Allergy Clin North Am. 2008; 28 (x): 665-686Abstract Full Text Full Text PDF PubMed Scopus (19) Google Scholar, 9Diette G.B. McCormack M.C. Hansel N.N. Breysse P.N. Matsui E.C. Environmental issues in managing asthma.Respir Care. 2008; 53: 602-615PubMed Google Scholar There is a paradox that has developed with regard to the role that pets have in asthma and atopic disease pathogenesis. It has been argued that many persons with pet allergy do not have cats in their homes, and conversely, many persons who live with mammalian pets do not have clinical disease.22Chan-Yeung M. McClean P.A. Sandell P.R. Slutsky A.S. Zamel N. Sensitization to cat without direct exposure to cats.Clin Exp Allergy. 1999; 29: 762-765Crossref PubMed Scopus (28) Google Scholar, 23Custovic A. Taggart S.C. Woodcock A. House dust mite and cat allergen in different indoor environments.Clin Exp Allergy. 1994; 24: 1164-1168Crossref PubMed Google Scholar It has been reported that owning mammalian pets might actually be protective against the development of atopy.24Ownby D.R. Johnson C.C. Peterson E.L. Exposure to dogs and cats in the first year of life and risk of allergic sensitization at 6 to 7 years of age.JAMA. 2002; 288: 963-972Crossref PubMed Google Scholar Whether this is due to associated increases in domestic endotoxin levels (which, according to the hygiene hypothesis, would protect against atopy) or development of immunologic tolerance is unclear.24Ownby D.R. Johnson C.C. Peterson E.L. Exposure to dogs and cats in the first year of life and risk of allergic sensitization at 6 to 7 years of age.JAMA. 2002; 288: 963-972Crossref PubMed Google Scholar However, there is strong consensus that in persons with IgE sensitization to mammalian pets and clinical disease, increased exposure to pet allergen is deleterious. Mold is a term that encompasses hundreds of species of saprophytic fungi that can be found in the indoor environment. Molds require high humidity and moisture, adequate temperature, and nutrients. It is clear that IgE sensitization can occur to molds, and there is great interest in the role these allergens play in asthma exacerbation and pathogenesis. Quantifying mold exposure can be very complex and is not standardized for clinical practice. Methods for this include culture of spores from recovered environmental samples, spore counts, and assessment of fungal allergens in recovered house dust or other fungal products (eg, 1-3 β-glucans, which themselves exert health effects). Of note, mold spores are between 2 and 10 μm in size and thus can remain in ambient air for extended periods of time. The variety of measures used in mold quantification has complicated the study of the role of indoor fungi in asthma. However, it is known that Alternaria species in outdoor settings is linked to increased asthma severity and airway reactivity. In the Inner City Asthma Consortium Studies indoor mold levels correlated well with outdoor levels, emphasizing that the outdoor environment plays an important role in establishing indoor mold levels. The National Academy of Science reviewed the relationship of mold and fungal exposures to asthma exacerbation and pathogenesis and stated that there was sufficient evidence that fungal allergen exposure caused disease exacerbation in sensitized subjects but that the existing data were inconclusive regarding the role of fungal exposures on disease pathogenesis. Combustion of biological matter results in notable indoor air pollution and often is due to burning of tobacco, wood, and other plant fuels.25Brims F. Chauhan A.J. Air quality, tobacco smoke, urban crowding and day care: modern menaces and their effects on health.Pediatr Infect Dis J. 2005; 24: S152-S156Crossref PubMed Scopus (14) Google Scholar, 26Gupta D. Aggarwal A.N. Chaudhry K. Chhabra S.K. D'Souza G.A. 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How exposure to environmental tobacco smoke, outdoor air pollutants, and increased pollen burdens influences the incidence of asthma.Environ Health Perspect. 2006; 114: 627-633Crossref PubMed Scopus (157) Google Scholar Burning of wood in indoor stoves and fireplaces generates a number of particulates and oxidant gases and is strongly associated with increased respiratory tract illness. However, environmental tobacco smoke (ETS; side-stream smoke from the burning end of a cigarette and exhaled mainstream smoke from a smoker) is the most significant and remediable indoor air pollutant in the United States. An example of the effect of ETS on indoor particulate levels is shown in a study of 11 hospitality locations (primarily restaurants) in which smoking and nonsmoking sections were maintained. 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