CHAPTER 6
Environmental Control (Avoidance)
Up to this point, the information given has been mostly concerned with various aspects of inhalant allergy. This is the most practical approach, as most new practitioners of allergy begin with the diagnosis and treatment of inhalant problems. Many experienced allergists also restrict their practice largely to the diagnosis and treatment of inhalant allergies, but we hope to guide the reader beyond this point. There will be failures in allergy diagnosis and treatment no matter how carefully problems are researched. Investigations into other aspects of allergy, discussed in later chapters, may reduce the frequency of such failures. Inhalant allergy, the best understood aspect of allergy and the form most responsive to therapy, is the logical place for the novice to start both diagnosis and therapy.
Practical means of reaching a definitive identification of offenders in inhalant allergy have already been discussed. This is a necessary precursor to treatment in the majority of cases and a valuable step in all cases, regardless of the form, or combination of forms, of treatment finally selected. It now becomes incumbent on the directing physician to discuss with the patient the various approaches to therapy available, and to select the most appropriate method or methods for each specific case.
This decision is not as complex as it might seem at first. Despite the advances in allergy care during the past several decades, there are still only three basic, accepted approaches to allergy care: (1) avoidance, (2) pharmacotherapy, and (3) immunomodulation. Most research efforts are currently directed at improved means of pharmacotherapy (seeking compounds with more effectiveness and fewer actual or potential side effects) and immunomodulation (methods of influencing the way in which the immune system reacts to inciting allergens, emphasizing treatment carrying less potential for adverse events and longer lasting effect). Nevertheless, allergen avoidance and environmental control measures remain an important part of the treatment of inhalant allergy. Whatever other methods may ultimately be required, allergen avoidance is a cornerstone of therapy.
NURSE’S NOTE
Environmental control is a prime teaching area for the allergy assistant. Education In this area requires more than one session. During multiple sessions with the patient, the opportunity exists for the allergy caregiver to repeat and clarify instructions, emphasize the importance of avoidance, and remind patients of simple control measures. The allergy department should be well stocked with printed information regarding environmental control, and this information should be given to patients. Avoidance is most important (and most feasible) in the case of patients who are sensitive to dust mites, mold, and animal danders, but it can also be emphasized to the pollen-allergic individual. In this area, the allergy nurse or assistant is always the most important source of information and encouragement for the patient. The physician should be asked to help in this endeavor by periodically asking patients if they are continuing to observe avoidance measures, thus underscoring to the patient the importance of this approach.
Allergists recognize that the ideal approach to the control of allergy is simply to have the patient avoid contact with the allergenic offender. If the patient never comes in contact with the allergen, no sensitization can occur. Although allergenic attachment sites are genetically determined and cannot be altered, even if the potential for sensitization is present, the site cannot be activated without several contacts with the potential allergen.
Even if sensitization becomes established through a series of allergenic exposures, producing allergic symptoms, further symptoms will not appear until additional contact with the allergen occurs. If, through conscious avoidance or lack of opportunity, the patient is not exposed to the allergen for a prolonged period of time, the immunologic progression that caused symptoms will gradually subside, so that future brief contacts with the allergen may not induce symptoms. This situation may lead to a false sense of security on the part of the patient. Nevertheless, it is always possible for full-blown allergic symptoms to develop in the sensitized patient if sufficient allergen exposure occurs. Consider the immune system to be acting as a computer, not an unreasonable comparison. A previous contact, repeated frequently enough to establish a predictable allergic reaction, has not appeared for a prolonged period of time. The response is still in the memory banks, but deeply buried. When a new exposure to the inciting allergen occurs, it may be insufficient to trigger that memory. If the exposure is repeated at frequent intervals, however, the immune system’s computer will eventually recall the previous adverse reaction and reactivate the progression, leading to allergic symptoms. The memory is never lost, simply buried.
The number of exposures required to reactivate the immune reaction is quite variable. Sometimes reactivation is almost immediate, whereas at other times it may require weeks or months. The time involved may also be affected by additional exposure to antigens that have allergenic combining sites (epitopes) in common with or extremely similar to those possessed by the antigen to which the patient is allergic. The speed and severity of the development of an allergic reaction may also be increased by exposure to other allergens to which the patient is sensitive (or even to nonspecific irritants), producing a “priming effect.” This effect is simply the result of the immune system’s becoming more sensitive to all stimulation, and reacting more rapidly and violently even when the primary offender is present in amounts normally too small to produce an allergic reaction. It is important to note that this response can also be triggered by nonantigenic stimuli, such as air pollution and cigarette smoke. Thus, avoidance measures aimed at these offenders also bear repeated emphasis by members of the allergy health care team.
As is well recognized, the ideal approach to inhalant allergy care is to avoid the offending allergen. Like most ideals, this approach is often very difficult to achieve. Effective control of multiple airborne allergens by avoidance is an almost impossible task. This limitation should not preclude an attempt to reduce allergenic exposures as much as possible, however, as any degree of reduction makes whatever additional form of treatment is elected more effective. Several approaches to environmental control are possible, all able to limit the degree of patient exposure, none likely to eliminate the problem effectively. Certain exceptions to this rule occur, most notably when the number of allergens involved is truly limited and when these allergens are confined to a small and predictable area. Unfortunately, this situation applies in a very small number of cases.
GEOGRAPHIC MOVE: DRASTIC AND NOT NECESSARILY PRODUCTIVE
It is common for the patient in whom allergies have developed and increased through successive years to broach the subject of a possible move to a different climate. This time-honored and usually impractical approach dates to the 19th century, was common during the 1930s and 1940s, and is still occasionally recommended today. The patient may hold out hope for this solution, but the physician should regard it with caution. It may work, but more often it will not. If a radical change of climate is involved, as in a move from the northeastern to the southwestern United States, a significant degree of improvement may well appear immediately after the move. This improvement is frequently temporary, however. Most allergic patients harbor a large number of immunologic attachment sites for potential allergens on their mast cells, and these may be activated by repeated exposures. The fact that such exposures have never occurred in the northeast is no guarantee that they will not occur in the southwest, where different potential allergens are present. As far as the future is concerned, only time will tell.
One source of information is an Internet search using the terms allergy and maps. As sites constantly change, no specific one is recommended here, but at the time of this writing several excellent resources were available. It is certainly worthwhile to consult such maps in advance if the patient is seriously considering a relocation. It would be of little value to advise a patient to move from one area of the country to another to reduce allergic exposure if the same allergens are present in the new area. It might surprise the physician as well as the patient to discover the wide distribution of a large number of major allergens throughout a large portion of North America, a situation that would make a geographic relocation useless for most patients.
Whether or not the distribution of allergens has been a significant factor in migration over much of the country, a major change in the distribution of the population of the United States has occurred in the past few decades. This in turn has resulted in some important changes in the ecology of various parts of the country. Arizona, for example, has had a great increase in population. This has resulted in the irrigation of large areas of desert that, although previously extremely dry, are now able to produce significant crops. All this change has benefited the population. On the down side, these areas now grow many crops with the same allergens previously present only in less arid areas, as well as quite a few new allergens, all of which may affect the allergic patient adversely. The end result of these changes in the ecology created by human ingenuity is that no area may be considered safe for the allergy patient on a long-term basis. The United States is growing and changing constantly. These changes, by and large, are beneficial to the economy and to the comfort of residents. The allergic patient, however, is an anomaly, representing a relatively small segment of the population. Although allergy represents one of the largest medical problems in the country, there is to date no accurate means of determining the future allergic potential of any particular location. A major geographic relocation is not a move to be undertaken lightly. An entire lifestyle may be expected to change, family and friends may be left behind, and a whole series of new challenges must be faced. Although the patient may be anticipating major lifestyle changes in any case, such as relocation for better employment opportunities or retirement, it would be unwise for a physician today to encourage such a move purely as a means of controlling allergic problems. The various factors affecting the allergic problem that may be influenced by a geographic relocation should be discussed with the patient, so that these factors may be considered realistically in relation to the other reasons for the move. The physician cannot then be accused of recommending such an action for medical reasons and creating in the patient the hope of receiving benefits that may prove to be unrealistic.
It is sometimes helpful to inquire whether the patient contemplating a geographic move has in fact lived in the area under consideration at some time in the past, and if so, for how long a period of time. Not infrequently, this will prove to be the case, with the patient weighing the benefits of returning to a familiar area that is remembered fondly. If the patient lived in the area for several years without allergic symptoms, the odds are better that the allergies will be less severe in that location. Even in that case, however, it is wise to advise the patient to check the degree to which the ecology of the region has been altered since the last time the patient resided there. Industrial or urban development over a previously pastoral area may affect the allergens present to a major degree. Furthermore, pollution due to increasing population and industrialization may contribute to respiratory symptoms that were not a problem in the past. The best approach is to advise the patient to make a trial move in the form of an extended visit to see if the climate is as beneficial as hoped. Even this is not totally without risk, as symptoms may change with seasons.
It must be acknowledged that even considering a geographic move in an attempt to control allergy is something that may be appropriate only for the allergic cripple. Such people are rare, but they do exist. They are sensitive to multiple airborne allergens, have major symptoms throughout the year, and respond poorly to antiallergic medication. They also have usually tried immunotherapy with unsatisfactory results. In such cases, a carefully planned geographic relocation may truly be of major benefit. Even when this move is pursued with the most careful investigation of the area beforehand, however, it is likely that the patient will continue to require some additional treatment. What can be hoped for is that routine treatment, previously inadequate, will now provide the relief sought, as the allergic load has been greatly reduced.
ENVIRONMENTAL CONTROL WITHOUT GEOGRAPHIC RELOCATION
The vast majority of patients are ill-equipped to embark on a geographic relocation to escape allergen exposure, even if the results are thought to be predictable. Allergy is an annoyance and a major burden, but it rarely produces a pronounced functional disability. Other lifestyle considerations, such as employment, education, and living conditions, usually take precedence over geographic relocation for allergen avoidance, at least until all other avenues of relief have been exhausted. Although environmental control is rarely completely effective in an area in which allergens to which the patient is sensitive abound, many measures are available to reduce the total allergenic impact. These measures may be categorized in a general way as control of indoor allergens and control of outdoor allergens, and include specific approaches to control of allergens to which the patient has been demonstrated to be sensitive. The former is the more widely used approach. However, understanding the way in which limiting exposure to specific allergens affects the effectiveness of approaches to overall inhalant allergen control may make the entire concept more understandable and allow the formulation of a plan appropriate for individual circumstances.
It is important to note here that environmental control represents an area in which ongoing instruction of the patient is required. The allergy caregiver has the opportunity, through recurring contact, to instruct patients continually in the appropriate measures for their particular situation and to reemphasize the need for environmental control and avoidance. Although immunotherapy is beneficial, it is never as helpful when the patient continues to be exposed to the offending allergens as when avoidance (within reason) is practiced. When a patient who is receiving immunotherapy complains of increasing problems, the physician should emphasize the importance of reasonable avoidance measures. The combination of emphasis by the physician and continuing instruction by the allergy nurse or assistant is the best possible method of obtaining compliance with avoidance measures.
Pollen Control
The control of exposure to seasonal pollens may be difficult without an alteration of lifestyle by the patient, a move that is often not practical. The seasons in which pollination reaches its peak also represent the times of year most conducive to outdoor activity. To review the seasonal pattern of pollination discussed previously, trees primarily pollinate in the spring, starting as early as late January or early February in some parts of North America. One species of tree may pollinate for a few weeks, but other species will have started to pollinate during this period of time, so that the overall tree pollination season may last into May or June, depending on the geographic area, temperature, and rainfall. Grasses pollinate primarily in summer, but the grass pollination season frequently overlaps the tree pollination season to some degree, and at times also extends into the fall weed pollination season. In some areas, grasses pollinate throughout the year, although the peak season is still the summer. Weeds primarily pollinate in the fall, starting in August and continuing into the period of the first frost, again depending on the area of the continent concerned. There are exceptions to these rules, such as the winter pollination of mountain cedar in the southwest, and these regional variations should be clarified before any program of allergy control is undertaken, regardless of the approach or approaches decided on.
NURSE’S NOTE
Principles of environmental control:
1. Take preventive measures. Avoid exposure by using filtering devices (e.g., dust mask, electrostatic filters). Avoid the allergic reaction by using nasal cromolyn or taking an antihistamine before an anticipated exposure.
2. Reduce continuing or unavoidable exposure. After allergen exposure, rinse the nose with saline solution. After mowing or gardening, dirty clothes should go directly into the washer, and the patient should shower and shampoo the hair. During periods of high pollen exposure (or air pollution), stay indoors in a controlled environment. Use the “recirculate” setting for automobile air conditioner. Keep windows closed at home, and use an effective filtration system.
FILTRATION DEVICES
Allergenic pollens usually fall into the size range of 15 to 50 jam, as described under Thommen’s postulates (Table 6-1). These pollens are usually filtered out by almost any efficient air-conditioner filter. The members of the allergy team should have a good general understanding of various types of air conditioner filters, as well as filtration systems in general. First, it must be recognized that the standard filter used with most air conditioners is not appropriate for the allergic patient. This filter may reduce the amount of debris being brought into the house through the air conditioner’s intake and further reduce the amount recirculated within the house, but the filtration properties are not adequate to remove the airborne particles that produce allergic reactions or are detrimental to respiratory function (Table 6-2). For the allergic patient, three basic types of filter may bear consideration.
For the pollen of a plant to be an important allergen, it must satisfy the criteria listed below, which were originally set forth by A. A. Thommen in 1931. Although exceptions may occur, these principles remain valuable in determining the probable allergenicity of plants encountered by patients. 1. The pollen must be wind-borne (anemophilous). This requirement rules out showy flowered plants with sticky pollen, which are insect-pollinated. 2. The pollen must be produced in large quantities. This is characteristic of wind-pollinated plants. 3. The pollen must be sufficiently buoyant to be carried considerable distances. This would include plants producing pollen grains in the size range of 15 to 58 mm. 4. The plant producing the pollen must be widely and abundantly distributed. 5. The pollen must contain specific excitants or antigens to produce hypersensitivity. Only gold members can continue reading. Log In or Register to continue
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