Exposure to multiple indoor allergens in US homes and its relationship to asthma

Background The National Survey of Lead and Allergensin Housing was the first population-based study to measure indoor allergenlevels in US homes. Objective We characterized the overall burden to multiple allergensand examined whether increased allergenlevels were associated with occupants' asthmastatus. Methods This cross-sectional study surveyed a nationally representative sample of 831 housing units in 75 different locations throughout the UnitedStates. Informationwas collected by means of questionnaire and environmental assessment. Allergenconcentrations in dust samples were assessed by using immunoassays. The following cutoff points were used to define increased allergenlevels: 10 μg/g for Der p 1, Der f 1, and Can f 1; 8 μg/g for Fel d 1; 8 U/g for Bla g 1; 1.6 μg/g for mouse urinary protein; and 7 μg/g for Alternaria alternataantigens. Allergenburden was considered high when 4 or more allergensexceeded increased levels in any of the sampling locations. Results Exposure to multiple allergenswas common in US homes. Of the surveyed homes, 51.5% had at least 6 detectable allergensand 45.8% had at least 3 allergensexceeding increased levels. Race, income, housing type, absence of children, and presence of smokers, pets, cockroaches, rodents, and mold/moisture-related problems were independent predictors of high allergenburden. Among atopic subjects, high allergenburden increased the odds of having asthma symptoms (odds ratio, 1.81; 95% CI, 1.04-3.15). Conclusion Increased allergenlevels in the home are associated with asthma symptoms in allergic individuals.