The Bi-air Filter Cassette: Sampling Airborne Fungal Spores in a Settling Chamber

The Bi-Air (BA) dual-trace 25 mm filter cassette was described, and its performance for the collection of Aspergillus/Penicillium (Asp/Pen) and Stachybotrys type spores in a clam-air settling chamber was compared to that of the Air-O-Cell (AOC) cassette. The BA produced duplicate sample traces, the sample traces were confined to two small, welldefined areas on the filter, and the small size of the sample traces made direct microscopic examination of the samples possible without requiring a sample transfer step prior to analysis. The BA was similar in size to the AOC, and had the same ease of use and analysis. However, the BA did not have the limitations of a slit impaction sampler for the collection of fungal spores. The average ratio of BA to AOC concentrations for Asp/Pen spores were 2.0 and 1.8 at airflow rates of 1 lpm and 2 lpm, respectively. The ratio decreased to 1.5 at an airflow rate of 3 lpm. The average ratios for Stachybotrys varied between 1.0 and 1.5 for the three airflow rates, with an average of 1.1. Practical implications. The BA, a 25 mm filter cassette, can be used for the routine collection and analysis of airborne fungal spores. It produced duplicate sample traces, the sample traces were confined to two small, well-defined areas on the filter, and the small size of the sample traces made direct microscopic examination of the samples possible without requiring a sample transfer step prior to analysis. The BA was more efficient at retaining small Asp/Pen type spores compared to the AOC, and had the same ease of use. However, the BA did not have the limitations of a slit impaction sampler for the collection of fungal spores. Bi-Air Chamber Tests 2