Exposure to an allergen is essential for the development of allergic sensitization. However, the quantity of allergen necessary for sensitization is not known and may depend on the individual and the allergen itself. For sensitization to dust mites, there does appear to be a dose–response relationship, with atopically predisposed individuals exposed to more allergen being more likely to become sensitized (Platts-Mills et al., 2001). In communities where most homes have concentrations greater than 10 µg of dust mite allergen per gram of dust collected (µg/g), the response of a majority of the allergic indi- viduals sensitized to mites appears to plateau, likely indicating a population-level satu- ration in.
