Aeroallergens play an important role in the pathogenesis of asthma and allergic rhinitis. In fact, allergen exposure is an important trigger in the exacerbation of symptoms in 80% to 90% of children with asthma.1 Indoor allergens in particular have been shown to be important and include house dust mite allergen, domestic pets, cockroaches, and mold. Studies have supported a connection between allergic sensitization (determined by IgE specific to the allergen), allergen exposure, and disease activity. There is also evidence to support me role of allergen avoidance in decreasing symptoms. Practical implementation and education regarding avoidance of relevant allergens should be considered first line in decreasing asthma morbidity in children with asthma. This article reviews the important indoor allergens and practical strategies for their avoidance.
DUST MITE ALLERGENS
In most areas of the world, house dust mites are major sources of allergens in the indoor environment and have been me most widely studied. One of the most important events in the history of allergic disease was when Voorhorst discovered that dust mites are the major allergen in house dust. The major species of dust mite associated with allergic disease include Dermatophagoides pteronyssinus and Dermatophagoides farinae,2 although several others have been identified. These allergens are cysteine proteases and enzymes primarily found in dust mite fecal pellets. The actual dust mite is an arachnid that lives in accumulated dust in homes. They inhabit carpets, upholstered furniture, mattresses, pillows, and bedding. Their major food source is shed human skin scales, and they grow optimally in areas that are both warm and humid, preferably with a humidity greater than 40%.3
The prevalence of dust mite allergy in children with asthma varies geographically. Studies have demonstrated prevalence rates ranging from 5% in Los Alamos, New Mexico,4 to 66% in Atlanta, Georgia,5 to 91% in Papua, New Guinea.6 These differences are roughly proportional to differences in dust mite exposure in different areas of the world, suggesting that higher exposure levels increase the risk of developing dust mite allergy.
In addition to the relationship between dust mite exposure and the development of dust mite allergy or sensitization, evidence suggests a relationship among exposure, sensitization, and the development of asthma. The role of allergen level and asthma development has been somewhat controversial. For example, Sporik et al.7 found a significant increase in asthma and dust mite sensitivity in 11 -year-old children who experienced high dust mite exposure during infancy. However, a later prospective study by the same investigators suggested that allergen levels predicted sensitization but not asthma. Several other studies have demonstrated associations between asthma development and dust mite sensitivity,2 but these studies were not prospective in nature. Given the complexity and multiple factors involved in asthma development, further study is desirable to understand the role of dust mite exposure and asthma development.
There is extensive evidence to support the relationship between dust mite exposure and disease activity among dust-mite sensitive asthmatics. For example, Custovic et al.8 clearly demonstrated a relationship between mite exposure and asthma severity by objecti ve and subjective measures. Multiple studies also showed that dust mite exposure is an important risk factor for acute asthma and emergency department visits.5 Regarding the link between asthma morbidity and exposure, the most compelling evidence for the role of dust mites in asthma comes from allergen avoidance studies, through environmental control strategies. Platts-Mills et al.9 led some of the earlier landmark studies that showed dramatic evidence for the benefits of dust mite avoidance among patients with asthma. The vast majority of subsequent trials have yielded similar results.
Dust Mite Allergen Avoidance and Patient Education
While most studies have evaluated secondary intervention strategies after asthma has developed, primary prevention environmental intervention trials are now being investigated.10 Preliminary studies showed mat reducing allergen exposure in early life is possible, but the exact role of these interventions in the prevention of asthma remains to be determined.
DUST MITE CONTROL MEASURES
Interventions in die home to reduce dust mite levels and exposure should be considered very important in children with asthma who demonstrate sensitivity or allergy to dust mites. These strategies have three interrelated goals: (1) reduce live mite populations; (2) reduce mite allergen levels; and (3) reduce human exposure to both. Important factors include cost of the intervention, ease of implementation, importance of the source of exposure, the safety of any chemicals used, and me potential benefit of the intervention.
Reducing indoor room humidity to below 50% is one of the most common recommendations, because dust mites require water from me air to survive. The use of high efficiency dehumidifiers and air conditioners in homes has recently been shown to be practical and effective.11
Encasing mattresses and pillows in specially manufactured protective coverings is extremely effective in reducing exposure to house dust mites and other allergens.12 In one study, polyurethane mattress encasings decreased mite allergen by 91%. Furthermore, washing sheets, pillow cases, blankets, and mattress pads at least weekly in hot water (550C or 1300F) kills dust mites and removes most of the allergen.13 It is interesting that washing the sheets in warm or cold water does not kill most mites but probably removes many of the allergens because they are water-soluble.13 Tumble drying is effective if a temperature of more than 5 5 0C or 1 300F is maintained for at least 10 minutes. Furthermore, while dry cleaning fabrics is effective in killing mites, it does not destroy all allergens.14
Carpets, draperies, and upholstery fabrics collect and hold moisture, providing an ideal habitat for mite breeding. In humid climates, carpets may be removed in favor of hard surfaces to decrease dust mite exposure. Furthermore, draperies and curtains may be replaced with blinds or shades for ease of dusting. Fabric upholstery may be replaced with vinyl or leather covering, and wooden furniture with no fabric is ideal. In homes where owners are not willing or unable to afford the expense of removing carpeting, vacuuming carpets at least weekly, frequent replacement of vacuum bags, and using two layer or high-efficiency particulate air filters in the vacuum are recommended. While regular vacuum cleaning removes surface mites and allergens, it will not remove deeply imbedded allergens or kill live mites. Furthermore, dust mites may be removed more easily from low pile or less dense carpets. Hot steam cleaning may also kill mites and remove allergens on the surface, but does not penetrate deep into padding, where large mite populations exist. In fact, residual water may actually promote mite population and growth.
Freezing soft toys and small items in -170C to -200C may be helpful in killing dust mites, and removing them from the bedroom has been shown to be helpful. Mite allergens are associated with dust particles greater than 20 µM in diameter, and these particles become airborne from disturbances but settle quickly. Therefore, air cleaning or filtration in undisturbed areas probably captures little dust mite allergen and is not usually helpful. Other measures such as duct cleaning and ozone generators have not been well studied. Use of chemicals has been somewhat controversial, and the benefits and the risk of using chemicals indoors have not been assessed fully. Experiments with acaricides such as benzyl benzoate, disodium octaborate tetrahydrate, sumethrin, and permethrin, and dénaturants such as tannic acid showed that a good active compound does not necessarily provide good dust mite or allergen control.9 Table 1 (page 42) provides a strategy of house dust mite allergen avoidance and patient education.
In most temperate humid areas of the world, dust mites are one of the most important sources of allergens associated with asthma and allergic disease. Therefore, interventions to achieve environmental control of these allergens can be extremely useful and should be considered very important for patients who suffer from allergen sensitivity and asthma.
Animal allergens are also a potent cause of both acute and chronic asthma symptoms. Cat and dog allergens are considered the most important; however, significant exposure to a wide variety of other furred animals is not uncommon related to the increasing variety of animals as household pets, including gerbils, rodents, hamsters, and rabbits. It has recently been estimated that between 60% and 70% of households in the western world have pets.15 Furthermore, sensitivity to cat and dog allergens occurs in up to 70% of children with asthma, and in some settings these allergens are clearly the dominant indoor allergens.4
The allergens of domestic cats and dogs and a wide variety of rodents and farm animals have been identified and characterized. Cat allergens are the most well studied and at least 12 proteins from cats have been found to be allergenic, with one major cat allergen, FeI d 1, being the most important. It is typically found in cat skin and hair follicles, and to a lesser extent, salivary glands. Although all breeds of cats, including long and short hair varieties, produce FeI d 1, male cats produce higher allergen levels than females; castrated males produce similar allergen levels to females.
Less is known about dog allergens, but several have been identified. The most important of these is Can f 1, which is present in hair, dander, and saliva. Major allergens from many rodents have also been identified, including mouse, rat, guinea pig, and rabbit. Urine is the major source of these rodent allergens with hair, dander, and saliva containing lesser amounts.16 Table 2 (page 44) shows the major animal allergens identified and their average molecular weights.
The characteristics of airborne cat allergen have also been studied extensively. They appear to be carried on particles that range from less than one micrometer to more than 20 µm in aerodynamic diameter, with a significant percentage carried on tiny particles less than 5 µp?. This enables cat allergen to remain airborne and dispersed for extended periods of time. Furthermore, the allergens' adherent nature allows easy transfer of allergens to environments that do not necessarily house the cat, such as other homes, offices, and school environments.17 Allergen level studies found that me wide dispersion of cat allergen may cause individuals to be exposed to clinically significant allergen levels even without known cat exposure.
As with dust mite allergen, the role of exposure to cat and dog allergen and me development of sensitization and asthma is unclear. Early studies showed mat intense exposure to cat allergen early in life leads to increased development of cat allergen sensitivity. However, recent studies have given conflicting results, with some suggesting that pet ownership and its associated increase in exposure is a risk factor for sensitivity and asthma, while others suggest that it is actually protective.18 It is also clear that pet sensitivity is common even in the absence of exposure and may be related to me widespread distribution of mese allergens. The role of other animal allergens such as rodents and farm animals in asthma development is largely unknown. As with dust mite allergen, multiple factors must contribute to the development of childhood asthma and sensitization. Therefore, further study is desirable to understand the precise role of animal allergens in disease development.
As with dust mite allergens, animal allergens clearly cause airway hyperresponsiveness in cat-allergen sensitive individuals with asthma, and investigators have documented increases in lung symptoms in cat-allergic asthmatics during environmental cat challenges in a cat room.19·20 Altiiough the role of intervention strategies to reduce exposure to cat allergen is not as well studied as for dust mite, decreasing exposure in patients already sensitized is clearly of benefit, and strategies for reducing exposure should be considered very important in managing and treating such patients.
Control of Animal Allergens
Much less is known about control of animal allergens than about the control of dust mite allergens. In fact, there are still no convincing studies on me clinical benefit of environmental control measures for animal allergens. While common sense assumes that removing an animal from the home will lead to improved symptoms in patients who have symptoms related to their pet, even this has not been proven. Most information regarding environmental control methods is available on cat allergen, and while most of these strategies may be applied to other allergens, further study is required before the environmental control measures can be made for other furred animals.
The first issue in control of cat allergens is removal of the pet from tiie home. If a patient has significant symptoms related to cat exposure, this recommendation must be stressed. Furthermore, patients should be informed that often it may take 4 to 6 months before allergen levels are significantly reduced to perceive clinical benefit.21 Otherwise, me patient may not see any immediate benefit and may assume that he or she is not really allergic to me pet. The allergen levels can fall more quickly if extensive environmental control measures are taken, such as removal of carpets, curtains, upholstered furniture, and otlier reservoirs for allergen. Thorough, aggressive, and repeated cleaning obviously will help decrease allergen levels faster. In addition, cat allergen may remain in mattresses years after removing me cat, so new bedding and encasements should be recommended.
Unfortunately, a high proportion of patients are unwilling to remove their household pet. Many people view pets as members of the family and refuse even to keep mem out of the bedroom or outside, let alone get rid of the pet completely. If the animal cannot be removed, there are several environmental control measures that can be implemented. Keeping the cat out of the bedroom or only outdoors may decrease allergen exposure; however, the sticky nature of the cat allergen allows for easy passive transfer, making control difficult. Recently there has been evidence that washing cats can reduce airborne allergen levels. A study by Avner et al.22 evaluated cat washing by several different methods and found reductions in airborne cat allergens by all methods. However, this decrease was not maintained for more than one week, suggesting that repeated and frequent washing is necessary. Practically, this is usually not well tolerated by most cats. Furthermore, while high-efficiency particulate air (HEPA) filters decrease airborne levels of cat allergen particles, studies show conflicting results as far as clinical efficacy. Until there are more definitive studies, I recommend restricting the pet to one area of the home (not the bedroom), removing reservoirs for allergen, especially in the bedroom, implementing mattress and pillow covers, and considering using HEPA filters. Removal of the pet should be stressed as the first line of intervention. Avoidance measures for dog should follow similar principles as those for cat, even though much less is known about dog and other pets or farm animals. Table 3 gives some basic strategies for avoidance of furred animal allergens.
Avoidance Measures for Furred Pet Allergens
The importance of cockroach allergens in asthma and allergy has been recognized only over the past 35 years. Now it is clear that cockroach allergens are an important cause of asthma, particularly in urban areas. In the United States, the prevalence of cockroach allergy ranges from 17% to 41% in both children and adults.23 In the last decade, studies of inner-city children with asthma found that sensitization and exposure to cockroach is associated with increased asthma morbidity, making this an important public health problem.24
Cockroach allergens derive from several sources including cockroach saliva, fecal material, secretions, cast skins, debris, and dead bodies. Two species, the German cockroach (Blatella germanica) and the American cockroach (Periplaneta americana) are the most common causes of household infestation and allergic sensitization. While several allergens from each species have been identified and characterized, the most important are Bla g 1 , Bla g 2, and Per a 1 , with most patients in the United States primarily sensitized to B germanica (Bla g 2 or 1 ).
Results of the National Cooperative Inner-City Asthma Study, which includes 1528 children with asthma from eight major inner-city areas, found that exposure to high levels of cockroach allergen was much more common than exposure to either dust mite or cat (50% for cockroach compared to 10% and 12% for dust mite and cat, respectively).24 This exposure correlated with an increase in sensitization rate and asthma morbidity,24 and suggests that cockroach is possibly a major factor in the high asthma morbidity in urban patient population. Not only has cockroach been found to be highly prevalent in inner-city homes, but recent studies found that urban schools may be a source of increased cockroach exposure and asthma morbidity.25
The role of cockroach allergen levels in the development of asthma in children is less well studied. In a birth cohort of 499 children of allergic or asthmatic parents, detectable cockroach allergen in the family room was a predictor of repeated wheeze in the first year of life,26 but fewer than half of those with recurrent wheeze in die first year of life developed astiima.27 Further study is needed to identify the precise role of cockroach allergen in asthma development.
Cockroach Allergen Control
Control of cockroach allergen exposure has been difficult. The National Cooperative Inner City Asthma group showed mat intervention based on extermination using abamectin resulted in decreased allergen levels in me kitchen but only for a short time, witli levels remaining above tliose considered clinically significant. More recently, strategies using different strengths of abamectin, hydramethylnon, and sodium hypochlorite have been helpful in decreasing cockroach allergen levels, but providing sustained control has proven difficult.23 It is suggested that cockroach extermination needs to be done in all rooms, coupled with thorough cleaning methods, addressing reservoirs of allergen in carpets, rugs, and other sites, and efforts to prevent reinfestations to achieve effective control of allergen exposure in the household.
There is another potential infestation that may be important in urban children with asthma. Recently, my colleagues and I evaluated the role of mouse allergens in inner-city populations through a follow-up study of me National Cooperative Inner-City Asthma Study. We studied 608 inner-city homes and found that 95% of all homes had detectable mouse allergen, suggesting a high prevalence of mouse allergen exposure.28 Furthermore, we found mat the development of mouse allergen sensitization significantly correlated with asthma morbidity,29 and this suggested that mouse infestation may be an important public health problem, particularly among sensitized children. Little is known about its role in asthma development, and we are currently involved in investigating environmental control strategies of mouse extermination and cleaning in attempts to decrease exposure to potentially important unique allergens to urban environments.
Mold allergen exposure is generally considered to arise from outdoor environments. However, many species invade homes through open windows and doors, or cracks in walls. Pénicillium and Aspergillus species are recovered at greater rates from within buildings than from die outdoor air, although they are abundant in soil. Altemaria mold species with Alt a I as me major allergen has been found in both indoor and outdoor environmental samples and correlates with severe or fatal asthma.
For me most part, fungal growth favors homes that are damp, have high humidity levels, or have cold surfaces onto which moisture can condense. Because of this, damp basements or humid bathrooms within an otherwise dry house can generate spores that spread throughout the house. Studies in Melbourne, Australia, found that mold levels were decreased in rooms with decreased dampness, were frequently vacuumed, lacked pets, and had smooth floors, as opposed to carpets.30 Furthermore, reference has been made to the term sick building, which refers to building materials, ventilation systems, or locations that appear to cause unhealthy environments; these can be in apartments, school, or office environments. While they usually do trigger allergy, some buildings may support high levels of fungal growth. The cause and effect relationship between exposure and symptoms is unclear.
As with other indoor allergens, fungal exposure and sensitization appear to be related to allergic disease and asthma. To date, however, no controlled trials have addressed mold environmental control strategies, and recommendations are largely empiric.
Exposure abatement in buildings heavily contaminated with mold can be extremely difficult and may require rebuilding of heavily damaged areas. When it is more localized, it may be possible to remediate the problem. Indoor mold exposure occurs through infiltration of spores from outdoors and through growth of mold indoors. Abatement strategies need to consider both sources of contamination.
The mainstay of mold control is to decrease humidity through air conditioning, cooling, and closing of doors. This can reduce spore infiltration. Small steps in the average home can significantly control moisture: (1) maintain indoor relative humidity at no greater than 50%; (2) seal all leaks to prevent water accumulation; (3) increase bathroom and kitchen ventilation by using exhaust fans; (4) vent clothes dryers to the outside; (5) reduce the excessive number of live indoor plants that must be watered; (6) use air conditioning during the summer months and at other times of high humidity levels; (7) heat all rooms in the winter and add heating outside wall closets; (8) use a dehumidifier in the basement or other areas of dampness; and (9) use a sump pump in basements that are prone to flooding.31
Carpets, wallpaper, paneling, and heating or air conditioning systems are known to harbor fungal spores. Therefore frequent vacuuming can reduce fungal spores levels. Washable wallpaper and paneling can be treated with a 5% bleach and detergent solution, but caution should be exercised when applying it as respiratory protection is necessary. Contaminated air ducts and filters may be cleaned to reduce mold exposure as well.
Air filters may remove particles from the air, with the most effective the highefficiency particle air filters. Electrostatic, electronic, and negative ionizers have shown a modest effect. In addition, regular maintenance, inspection, and cleaning of heating, ventilation, and airconditioning systems is necessary because spores can circulate through the building. Finally, a person who is highly sensitive to mold should use particulate masks when involved in activities such as cleaning that can disperse spores in the air. People with severe allergy should avoid handling, vacuuming, and cleaning areas of fungal contamination.
INDOOR AIR POLLUTION
A detailed discussion of indoor air pollution is beyond the scope of this article, but it should be emphasized that effective environmental control related to nonspecific irritants also deserves attention. The effects of passive cigarette smoke on pediatric asthma were well documented in several studies.32 In addition, nitrous oxide (from sources such as gas stoves and space heaters) and wood smoke have been documented to exacerbate pediatric asthma. All patients should be asked about these exposures and counseled in thier control. Parents who smoke need to be reminded at each visit about the ongoing damage caused by chronic exposure to themselves and their children.
Indoor allergens are potent triggers for acute and chronic pediatric asthma. Environmental control of these allergens should be considered important treatment measures. Allergen avoidance can produce changes in disease activity and symptoms that can be beneficial before even any medical intervention is implemented. This therapy is safe, cost-effective, and logical. Although it takes some continued effort, the benefits are real.
1. Schwartz J, Weiss ST. Relationship of skin test reactivity to decrements in pulmonary function in children with asthma or frequent wheezing. Am J Respir Crit Care Med. 1995;152(6 Pt 1):2176-2180.
2. Platts-Mills TA, Vervloet D, Thomas WR, Aalberse RC7 Chapman MD. Indoor allergens and asthma: report of the Third International Workshop. J Allergy Clin Immunol. 1997;100(6 Pt l):S2-24.
3. Vojta PJ, Randels SP, Stout J, et al. Effects of physical interventions on house dust mite allergen levels in carpet, bed, and upholstery dust in low-income, urban homes. Environ Health Perspect. 2001;109:815-819.
4. Ingram JM, Sporik R, Rose G, Honsinger R, Chapman MD, Platts-Mills TA. Quantitative assessment of exposure to dog (Can f 1) and cat (FeI d 1) allergens: relation to sensitization and asthma among children living in Los Alamos, New Mexico. J Allergy Clin Immunol. 1995;96:449-456.
5. Call RS, Smith TF, Morris E, Chapman MD, Platts-Mills TA. Risk factors for asthma in inner city children. J Pediatr. 1992;121:862-866.
6. Dowse GK, Turner KJ, Stewart GA, Alpers MP, Woolcock AJ. The association between Dermatophagoides mites and the increasing prevalence of asthma in village communities within the Papua New Guinea Highlands. J Allergy Clin Immunol. 1985;75(1 Pt l):75-83.
7. Sporik R, Holgate ST, Platts-Mills TA, Cogswell JJ. Exposure to house dust mite allergen (Der ? I) and the development of asthma in childhood. A prospective study. N Engl J Med. 1990;323:502-507.
8. Custovic A, Taggart SC, Francis HC, Chapman MD, Woodcock A. Exposure to house dust mite allergens and the clinical activity of asthma. J Allergy Clin Immunol. 1996;98:64-72.
9. Platts-Mills TA, Vaughan JW, Carter MC, Woodfolk JA. The role of intervention in established allergy: avoidance of indoor allergens in the treatment of chronic allergic disease. J Allergy Clin Immunol. 2000;106:787-804.
10. Custovic A, Simpson BM, Simpson A, et al. Manchester Asthma and Allergy Study: low-allergen environment can be achieved and maintained during pregnancy and in early life. J Allergy Clin Immunol. 2000;105:252-258.
11. Arlian LG, Neal JS, Morgan MS, Vyszenski-Moher DL, Rapp CM, Alexander AK. Reducing relative humidity is a practical way to control dust mites and their allergens in homes in temperate climates. J Allergy Clin Immunol. 2001;107:99-104.
12. Vaughan JW, McLaughlin TE, Perzanowski MS, Platts-Mills TA. Evaluation of materials used for bedding encasement: effect of pore size in blocking cat and dust mite allergen. J Allergy Clin Immunol 1999;103(2 Pt 1):227-231.
13. McDonald LG, Tovey E. The role of water temperature and laundry procedures in reducing house dust mite populations and allergen content of bedding. J Allergy Clin Immunol. 1 992;90(4 Pt 1 ):599-608.
14. Miller JD, Miller A. Ten minutes in a clothes dryer kills all mites in blankets [abstract]. J Allergy Clin Immunol. 1996;97:423.
15. Gordon S. Allergy to furred animals. Clin Exp Allergy. 1997;27:479-481.
16. Bush RK. Mechanism and epidemiology of laboratory animal allergy. liar Journal. 2001;42(1):4-11.
17. Bollinger ME, Eggleston PA, Flanagan E, Wood RA. Cat antigen in homes with and without cats may induce allergic symptoms. J Allergy Clin Immunol. 1996;97: 907-914.
18. Svanes C, Jarvis D, Chirm S, Burney P. Childhood environment and adult atopy: results from the European Community Respiratory Health Survey. J Allergy Clin Immunol. 1999,103(3 Pt l):415-420.
19. Phipatanakul W, Kesavanathan J, Eggleston PA, Johnson EF, Wood RA. The value of acoustic rhinometry in assessing nasal responses to cat exposure. J Allergy Clin Immunol. 1998;102(6 Pt 1):896-901.
20. Phipatanakul W, Nowak-Wegrzyn A, Eggleston PA, et al. The efficacy of montelukast in the treatment of cat allergeninduced asthma in children. J Allergy Clin Immunol. 2002;109:794-799.
21. Wood RA, Chapman MD, Adkinson NF, Jr., Eggleston PA. The effect of cat removal on allergen content in household-dust samples. J Allergy Clin Immunol. 1989;83:730-734.
22. Avner DB, Perzanowski MS, Platts-Mills TA, Woodfolk JA. Evaluation of different techniques for washing cats: quantitation of allergen removed from the cat and the effect on airborne FeI d 1. J Allergy Clin Immunol. 1997;100:307-312.
23. Arruda LK, Ferriani VP, Vailes LD, Pomes A, Chapman MD. Cockroach allergens: environmental distribution and relationship to disease. Current Allergy & Asthma Reports. 2001;1:466-473.
24. Rosenstreich DL, Eggleston P, Kattan M, et al. The role of cockroach allergy and exposure to cockroach allergen in causing morbidity among inner-city children with asthma. N Engl J Med. 1997;336:13561363.
25. Sarpong SB, Wood RA, Karrison T, Eggleston PA. Cockroach allergen (Bla g 1) in school dust. J Allergy Clin Immunol. 1997;99:486-492.
26. Gold DR, Bürge HA, Carey V, Milton DK, Platts-Mills T, Weiss ST. Predictors of repeated wheeze in the first year of life: the relative roles of cockroach, birth weight, acute lower respiratory illness, and maternal smoking. Am J Respir Crit Care Med. 1999;160:227-236.
27. Martinez FD, Wright AL, Taussig LM, HoIberg Q, Halonen M, Morgan WJ. Asthma and wheezing in the first six years of life. The Group Health Medical Associates. N Engl ] Med. 1995;332:133-138.
28. Phipatanakul W, Eggleston PA, Wright EC, Wood RA. Mouse allergen. I. The prevalence of mouse allergen in innerdry homes. The National Cooperative Inner-City Asthma Study. J Allergy Clin Immunol. 2000;106:1070-1074.
29. Phipatanakul W, Eggleston PA, Wright EC, Wood RA, The National Coooperative Inner-City Asthma S. Mouse allergen. ?. The relationship of mouse allergen exposure to mouse sensitization and asthma morbidity in inner-city children with asthma. J Allergy Clin Immunol. 2000;106:1075-1080.
30. Dharmage S, Bailey M, Raven J, et al. Prevalence and residential determinants of fungi within homes in Melbourne, Australia. Clin Exp Allergy. 1999;29:1481-1489.
31. Bush RK, Portnoy JM. The role and abatement of fungal allergens in allergic diseases. J Allergy Clin Immunol. 2001;107(3 Suppl):S430-440.
32. Chilmonczyk BA, Salmun LM, Megathlin KN, et al. Association between exposure to environmental tobacco smoke and exacerbations of asthma in children. N Engl J Med. 1993;328:1665-1669.
Dust Mite Allergen Avoidance and Patient Education
Avoidance Measures for Furred Pet Allergens