Indoor factors associated with concentrations of house dust mite allergen,Der p 1, in a random sample of houses in Norwich, UK

Background Studies of house dust mite allergen concentrations suggest large variations both within and between homes. It is likely that different hous ehold characteristics influence allergen levels in different locations with in the house. Objectives To investigate household characteristics associated with higher concentrations of house dust mite allergen in a random sample of houses. Methods Information on indoor environment was obtained from 158 adults aged 20-44. Dust samples were collected from their living room floor, bedroom f loor and mattress. Concentrations of Der p 1, the major allergen from the h ouse dust mite Dermatophagoides pteronyssinus, were measured by monoclonal antibody immunoassay. Associations between mite allergen concentrations and household characteristics were examined using censored-normal regression m odels. Factors that were related to Der p 1 (P less than or equal to 0.2) i n univariate analyses were included in multivariable regression models. Results Der p 1 was not detected in any location in 10 (6.3%) houses. Geome tric mean concentrations of Der p 1 were 1.9 mu g/g in living room floor du st, 1.7 mu g/g in bedroom floor dust and 2.0 mu g/g in mattress dust. Appro ximately 25% of living room floor and mattress, and over 30% of bedroom flo or samples had Der p 1 concentrations greater than 10 mu g/g. Household cha racteristics associated with Der p 1 concentrations in both living room and bedroom were floor level, extractor fan in the kitchen, and age of carpet. Living room Der p 1 concentrations were also associated with gas oven/hob, window condensation, open fires, vacuum cleaner type, smokers in the house and age of house. Bedroom Der p 1 concentrations were also associated with use of blankets and wash temperature of bedding. Mattress Der p 1 concentr ations were associated with window condensation, concrete bedroom floor and age of mattress. Conclusion Different household characteristics were associated with high De r p 1 concentrations in different parts of the house. These findings are re levant to design of allergen avoidance regimes or formulation of policy rec ommendations for reduction of disease associated with allergen exposure.