Monthly measurements of indoor allergens and the influence of housing type in a northeastern US city

Background: We examined seasonal variation of dust-mile (Der f 1 and Der p 1), cat (Fel d 1), and cockroach (Bla g 1) allergens in Boston, while adjusting for other covariates. Limited data are available on seasonal patterns of indoor allergen concentrations for different geographic regions in the USA. Understanding within-home seasonal variation of allergens is important epidemiologically and clinically. Methods: From June 1995 to June 1996, dust samples were vacuumed monthly from the bed, bedroom floor; and kitchen of 20 homes. Indoor temperatures were measured monthly and used in calculating relative and absolute humidity. Monthly home characteristics questionnaires were completed by an adult resident of each home. Dust samples were assayed by enzyme-linked immunosorbent assays. Results: Der f I and Der p 1 in beds and floors peaked in the autumn months, Fel d 1 peaked in winter and spring, and Bla g 1 was highest in summer. Dust-mite allergen concentrations were 1.9-2.4 times higher in autumn than spring, but the levels in beds were 19-31 times higher in houses than those in apartments. Although Fel d 1 levels in beds were 2.4 times higher in spring than summer, homes with cats had levels 224 times higher than those without cats. Similarly, Bla g 1 levels in kitchens were 2.1 times higher in summer than winter, but apartments had, levels five times higher than those of houses. Conclusions: Sampling season is a source of within-home dust-mite, fat, and cockroach allergen variation in-the northeastern USA. However, the influence of housing type and owning a cat far outweighed the seasonal Variation of these indoor allergens.