potential for a threshold level of exposure below which the risk of sensitization is reduced, is of critical importance in the prevention and control of allergic disease. Epidemiological data would be useful in determining these relationships and in developing and evaluating public health and medical intervention strategies.

Research Agenda Item: Conduct appropriate epidemiological studies of exposure-response relationships of important defined indoor allergens that induce sensitization in humans. Such studies should include a focus on identifying threshold exposures.

Indoor allergens are associated with a wide variety of particles in a broad size range, only some of which are microscopically identifiable, culturable, or detectable with existing immunoassays. Evaluation of indoor allergens requires both air and source sampling, and several different analytical techniques (including microscopy, culture, and immunoassays) must be used to characterize even the well-known allergens. Because of the complexity of the assessment problem, indoor allergens, with a few exceptions, have not been identified and studied.

Research Agenda Item: Encourage and conduct additional research to identify and characterize indoor allergens. The new information should be used to advise patients about avoiding specific allergenic agents.