Household dust and respiratory allergy: A study of household dust exposure and respiratory allergy in UK households.

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