This study showed a strong association between asthma, hay fever, and eczema in the same child. The presence of pets outdoors but not indoors appeared to be associated with an increased incidence of wheezing in children. Use of the traditional Gulf incense also appeared to be a precipitating factor for asthma in this study. There were also statistically significant relationships between asthma and exposure to dust at home from air conditioner blasts, which is consistent with studies elsewhere. Moreover, in this study, passive exposure to tobacco smoking at home did not appear to have any significant relationship with asthma. There was, however, a statistically significant relationship between asthma and exposure to pollen from indoor plants, which is also consistent with studies elsewhere. Parental asthma but not parental atopy was a significant risk factor for asthma in offspring, a finding which agrees with other studies that have shown that parental atopy may enhance the likelihood of the expression of asthma, but does not, on its own, impact as a risk factor in the same way as parental asthma. There was a statistically significant difference in the prevalence of asthma and the symptoms of asthma between different areas across the United Arab Emirates, but not for eczema or hay fever. This is most likely attributable to the impact of radically different environmental conditions on the development of allergies in two genetically homogenous populations of United Arab Emirates nationals. Asthma, wheeze, dyspnoea and nocturnal cough were more prevalent in coastal humid Dubai, compared to dry inland Al-Ain. However, there was no statistically significant difference in the prevalence of eczema and hay fever between coastal and inland areas in the United Arab Emirates. An environmental survey carried out in Dubai and Al-Ain to study the effect of air pollution among asthmatic children showed that overall air quality in both Dubai and in Al-Ain is good, except during adverse weather conditions, strong winds and dust storms, in summer time, where the level of Respirable Particulates (PM10) is occasionally high in Dubai. However, a previous study of seasonal trends in hospital admissions for asthmatic children in Dubai showed that the highest numbers of admissions for asthmatic children occurred between the months of October and February. These are the coldest months of the year in the United Arab Emirates. Therefore air pollution from dust storms was not the cause of the high prevalence of asthma in Dubai. Although the prevalence of asthma and wheezing was lower in the United Arab Emirates than in some developed countries, it was still higher than other chronic diseases. This study demonstrated that symptoms suggestive of asthma are quite common and constitute a major health problem in the United Arab Emirates. High rates of consanguineous marriage, a buoyant economy, rapid industrialization, development of the agricultural sector, an increase in the domestication of animals and dairy farms, combined with an emphasis on 'greening' the environment, may have resulted in an increase of the prevalence of asthma. World-wide trends have been in this direction. Therefore, a concentrated effort should be made to implement therapeutic and non-therapeutic programmes for the management of asthma by parents, teachers and physicians.

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This thesis is designed to explore the hypothesis that settled dust in a domestic environment can contain significant levels of allergens and that common cleaning methods employed to remove dust can result in sufficient airborne exposure to potentially trigger an allergic reaction. Qualitative feedback from respondents in studies of furniture dusting habits indicated that household furniture dusting could elicit an allergic response. A consumer questionnaire was fielded to confirm the problem and it's magnitude. This indicated that it affected approximately 20% of allergy sufferers (or approximately 5% of the total UK population). Further work was performed to estimate the level of allergen exposure during dusting. Additional consumer research was fielded to ascertain the surface area being dusted, (approximately 54000cm2 for frequently dusted areas and 10000cm2 for frequently dusted areas). Domestic dusting habits were probed for the relative frequency of dusting method, which split evenly between dry dusting, wet dusting with water and wet dusting with a furniture polish. Surface sampling techniques were adapted to make in-home measurements of the rate of dust settling which was found to be approximately 3.19x10 -7 g.cm-2,day-1. In-home sampling was also undertaken to measure the mean allergen content of surface dust for major allergens, yielding 24667ng.g-1 combined dust mite, 47696ng.g-1 Fel d 1 and approximately 126 8 08ng.g-1 Can f 1. Laboratory-based studies determined the relative amount of dust rendered airborne during dusting of different furniture surface types and comparing different cleaning methods. This was found to be between 2.3- 43.0%. From these experiments, a model "average" home was constructed and used to estimate the exposure towards dust allergens during a typical dusting task. Exposure was estimated to be as much as 16500ng total dust mite, 124000 mug (31000 mU) cat allergen and 275000 ng (IU) dog allergen per dusting method. These results indicated that allergen exposure, under certain circumstances, could exceed the threshold levels that have been proposed for the onset of sensitisation.

In the world today, asthma affects more than 235 million people. The widespread prescription of inhaled corticosteroids—the current gold standard of asthma control medication—allows many asthmatics to live symptom-free and has significantly reduced the number of deaths due to asthma. However, when the disease is poorly controlled, for example due to ubiquitous exposure to airborne fungal conidia, this chronic inflammatory disease often results in lung dysfunction caused by airway architectural changes. The role of B lymphocytes in allergic asthma has been relegated to the production of IgE with relatively little being known about the trafficking of these cells in the tissues or their role(s) in the affected tissue. As a first step in ascertaining their function, the initial aim of this project was to characterize the recruitment and localization of B cells in the murine lung in response to Aspergillus fumigatus inhalation. We found that CD19+CD23+ B2 lymphocytes were recruited to the lungs after fungal inhalation and that IgA-, IgE-, IgG-producing cells localized around the large airways. The second aim of the project was to begin defining the impact that these B lymphocytes have on the allergic lung. By using mice that were deficient of conventional B cells, we were able to demonstrate that the allergic phenotype was retained, although the impact of tissue B1 B cells cannot yet be ruled out. We then investigated the ability of hyaluronic acid (HA), a major component of the extracellular matrix (ECM) generated at sites of chronic inflammation, to recruit and modulate B lymphocyte functions in allergic fungal disease. We found that B lymphocytes undergo chemotaxis in response to LMM HA, while HMM HA had little to no effect on B cell chemotaxis. Furthermore, HA-mediated B lymphocyte chemotaxis was significantly inhibited by blocking the CD44 HA receptor. We also demonstrated that LMM HA fragments elicit the production of the pro-fibrotic cytokines IL-10 and TGF-β1 by B lymphocytes. These observations suggest a previously unrecognized role for B lymphocytes and HA in the context of allergy and represent novel pathways by which B lymphocytes may contribute to airway inflammation and airway remodeling.

Allergic diseases are common in women of childbearing age. Both asthma and atopic conditions may worsen, improve or remain the same during pregnancy. Primary care physicians commonly encounter women receiving multiple medications for pre-existing atopic conditions, who then become pregnant and require medication changes to avoid potential fetal injury or congenital malformations. Each medication should be evaluated; intranasal and inhaled steroids are relatively safe to continue during pregnancy (budesonide is the drug of choice), second-generation antihistamines of choice are cetirizine and loratadine, leukotriene receptor antagonists are safe, sparing use of oral decongestants during the first trimester and omalizumab may be used for both uncontrolled asthma and for antihistamine-resistant urticaria. Medications to avoid during pregnancy include intranasal antihistamines, first-generation antihistamines, mycophenolate mofetil, methotrexate, cyclosporine, azathioprine and zilueton. Common allergic diseases may develop de novo during pregnancy, such as anaphylaxis.