Effects of physical interventions on house dust mite allergen levels in carpet, bed, and upholstery dust in low-income, urban homes

House dust mite allergen exposure is a postulated risk factor for allergic sensitization, asthma development, and asthma morbidity; however, practical and effective methods to mitigate these allergens from low-income, urban h ome environments remain elusive. The purpose of this study was to assess th e feasibility and effectiveness of physical interventions to mitigate house dust mite allergens in this setting. Homes with high levels of house dust mite allergen (Der f1 + Der p 1 greater than or equal to 10 mug/g dust by e nzyme-linked immunosorbent assay) in the bed, bedroom carpet, and/or uphols tered furniture were enrolled in the study. Carpets and upholstered furnitu re were subjected to a single treatment of either dry steam cleaning plus v acuuming (carpet only) or intensive vacuuming alone. Bed interventions cons isted of complete encasement of the mattress, box spring, and pillows plus either weekly professional or in-home laundering of nonencased bedding. Dus t samples were collected at baseline and again at 3 days (carpet and uphols tery only) and 2, 4, and 8 weeks posttreatment. We compared pretreatment me an allergen concentrations and loads to posttreatment values and performed between-group analyses after adjusting for differences in the pretreatment means. Both dry steam cleaning plus vacuuming and vacuuming alone resulted in a significant reduction in carpet house dust mite allergen concentration and load (p < 0.05). Levels approached pretreatment values by 4 weeks post treatment in the intensive vacuuming group, whereas steam cleaning plus vac uuming effected a decrease that persisted for up to 8 weeks. Significant de creases in bed house dust mite allergen concentration and load were obtaine d in response to encasement and either professional or in-home laundering ( p < 0.001). Between-group analysis revealed significantly less postinterven tion house dust mite allergen load in professionally laundered compared to home-laundered beds (P < 0.05). Intensive vacuuming and dry steam cleaning both caused a significant reduction in allergen concentration and load in u pholstered furniture samples (p < 0.005). Based on these data, we conclude that physical interventions offer practical, effective means of reducing ho use dust mite allergen levels in low-income, urban home environments.