Passive airborne dust sampling to assess mite antigen exposure in farming environments.

The aim of this study was to estimate mite antigen exposure in farming environments by passive sampling of airborne dust. Antigen concentrations were measured with enzyme immunoassays specific for three storage mites (SM): Acarus siro, Lepidoglyphus destructor, Tyrophagus putrescentiae and the house dust mite (HDM) Dermatophagoides pteronyssinus. Dust samples were collected with electrostatic dust fall collectors (EDCs) in three different areas of cattle farms. EDCs were placed in cow stables (working area), in changing rooms (transit area) and in different rooms of farmer dwellings (living area). Mite concentrations in the living area of farm homes were compared to those of urban homes. In dust samples from stables, antigens of all four mite species could be detected. The highest exposure level was to L. destructor (median 56.7 μg/m(2)), the lowest to A. siro (median 14.4 μg/m(2)). Mite concentrations of different species showed no correlation within the cow stables. In comparison to stables, the median mite concentrations in farm homes were significantly lower, ranging from below the detection limit to 1.5 μg/m(2). Antigens of SM were predominantly found in changing rooms and kitchens, and HDM antigens were mainly detected in bedrooms. Antigens of all mites were measured the least often in living rooms. T. putrescentiae was the most prevalent mite in all room types, and the exposure levels correlated strongly between different rooms. The number of SM positive samples in farm homes was considerably higher than in urban homes, while the percentage of HDM positive samples did not differ significantly.