Evaluation of air and dust sampling schemes for Fel d 1, Der f 1, and Der p 1 allergens in homes in the Detroit area

Background: Studies often use a point estimate of allergen exposure without fully justifying the accuracy of this single measure as an estimate of total exposure. Many studies have reported relationships between indoor allergen concentrations and manifestations of allergic disease on the basis of single samples. Objectives: The purposes of this study were to (1) characterize the variability in dust and air concentrations of allergens, (2) assess the relationships between dust and air concentrations of allergens, and (3) determine the minimum number and timing of samples to characterize annual indoor allergen exposure. Methods: As part of a prospective cohort study of asthma in children, air and dust samples were repeatedly obtained from the homes of children residing in suburban Detroit, Michigan. Concentrations of Fel d 1, Der f 1, and Der p 1 were measured in the samples. The results of various patterns of sampling were compared with yearly averages. Results: The concentrations of all 3 allergens in both air and dust varied widely both within and between homes. The allergen concentrations had peak concentrations in the fall. There was little correlation between air and dust concentrations. Our results indicate that as few as 2 or 3 samples taken late in the year provide good estimates of the annual average concentrations. Conclusions: Two or 3 samples, obtained 1 month apart and taken late in the year, represent the best balance between sampling effort and accuracy of the yearly exposure estimates of Fel d 1, Der f 1, and Der p 1 in temperate climates similar to those of Detroit, Michigan.