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 tot al exposure. Many studies have reported relationships between indoor allerg en concentrations and manifestations of allergic disease on the basis of si ngle samples. Objectives: The purposes of this study were to (1) characterize the variabi lity in dust and air concentrations of allergens, (2) assess the relationsh ips between dust and air concentrations of allergens, and (3) determine the minimum number and timing of samples to characterize annual indoor allerge n exposure. Methods: As part of a prospective cohort study of asthma in children, air a nd dust samples were repeatedly obtained from the homes of children residin g in suburban Detroit, Michigan. Concentrations of Fel d 1, Der f 1, and De r p 1 were measured in the samples. The results of various patterns of samp ling 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 du st concentrations. Our results indicate that as few as 2 or 3 samples taken late in the year provide good estimates of the annual average concentratio ns. 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 t he yearly exposure estimates of Fel d 1, Der f 1, and Der p 1 in temperate climates similar to those of Detroit, Michigan.