A sampling method for comparing fungal concentrations in carpets

A microvacuum method is described for sampling fungal contaminants in carpet dust and reporting the results on an area basis. When sampling parameters such as suction force, contact time, and area sampled were held constant, and the results were reported on an area basis, fungal concentrations were associated with the potential for water intrusion, a determinant of exposure. Carpet dust samples were collected in open-face 25-mm cassettes containing 0.8 micro m mixed cellulose ester filters. The airflow rate was calibrated at 10 L/min, and the open-faced cassette was held firmly against the carpet at 20 separate spots for a period of 5 sec at each spot. An area of 98 cm(2) of carpet was sampled with each cassette. A total of 58 carpet dust samples were collected in 31 residential condominium units using the described methodology. The carpets were stratified into three groups: (1) controls and those at centers of rooms, (2) at sliding glass doors and under windows, and (3) in areas of water intrusion reported by the occupant. The geometric mean concentrations (GM) of total fungi increased in the listed order, as did the GM concentrations of Penicillium spp. and Aspergillus spp. detected in the samples. In addition, the 95% confidence intervals on the GM concentrations for total fungi could be used to classify the carpets into three groups: uncontaminated, potentially contaminated, and contaminated.