Factors affecting the retention of dust mite allergen on carpet

Carpeting is one of the most common and perhaps the most important reservoir of aeroallergens and other components of dust found in residential or commercial settings. This research evaluated factors that affect the retention of dust mite allergens on different types of tufted carpet commonly found in homes and offices. Twenty-six types of carpet were custom manufactured as part of a two-stage factorial experiment using 182 carpet samples. Carpets differed with respect to fiber denier, cross-sectional shape, presence of fluorocarbon treatment, carpet style, pile height, and pile density. The major hypothesis tested was that the amount of allergen-containing dust recovered from vacuum samples of tufted carpet sources was dependent on micro (fiber) or macro (construction) retention characteristics of the carpets. Carpet samples were doped in a uniform and reproducible manner using an allergen-containing reference dust. A standardized vacuum surface sampler was used to recover dust from samples. Allergen was assayed using a standard, monoclonal antibody ELISA. Carpet-surface area and presence of fluorocarbon were found to have the largest effects on retention and recovery of dust and allergen. Specifically, fluorocarbon treatment of fibers, square-hollow fiber shape, high-denier fiber, low-pile height in cut-pile carpets, and low-pile density in loop carpets were significantly associated with increased release and recovery of allergen. Results from this study suggest that carpet type be considered for both allergen avoidance and allergy and asthma risk assessment.