A Comparison of Replicate Field Samples Collected with the Bi-Air,Air-O-Cell,and Graesby-Andersen N6 Bioaerosol Samplers

The Bi-Air (BA) and Air-O-Cell (AOC) cassettes have been compared for the collection of Aspergillus/Penicillium (Asp/Pen) and Chaetomium spores based on replicate and/or duplicate samples collected under typical field conditions. Total culturable Asp and Pen concentrations were also compared for the BA and the N6 impactor based on duplicate field samples. When single Asp/Pen spores or small chains were dominant, the average BA:AOC concentration ratio was 2.1 (11,260 spores/m³ v 5,400 spores/m³) for six duplicate samples collected in a well-mixed room. This ratio was consistent with previous studies performed under controlled conditions. However, the average BA:AOC concentration ratio was 54 (765,00 spores/m³ v 36,800 spores/m³) for four replicate samples in which small Asp/Pen spores and clusters of Asp/Pen spores were dominant. The average BA:AOC concentration ratio for Chaetomium was typically 8.6, with a high of 100 for the four replicate samples in which Asp/Pen clusters were dominant. It was concluded that the performance of the BA and the AOC, except for a reasonably constant 2:1 ratio of concentrations, were similar for the detection of single Asp/Pen spores or small chains. However, the BA generally detected higher concentrations of Asp/Pen spores when clusters were dominant; and detected Chaetomium spores in more of the replicate field samples and at a higher average concentration.

The average concentrations of culturable Aspergillus and Penicillium were not statistically different for six duplicate N6 and BA samples collected in a well-mixed room. For nine duplicate field samples with N6 concentrations of total culturable fungi greater than 1,000 cfu/m³, the N6 and BA were moderately correlated (r = 0.76). It was concluded that the ability of the BA to collect culturable fungi was similar to that of the N6 for short-term samples.