Chamber Evaluation of a Personal, Bioaerosol Cyclone Sampler

Abstract

A personal cyclone sampler (cyclone) was operated in a 0.9-m³ chamber, side by side with a 25-mm filter sampler (filter) and either a slit impactor (Air-O-Cell) or a single-stage, multiple-hole, agar impactor (N6). Aerosols of two fungal spores were collected for 5 min to 5 hr—Aspergillus versicolor: 10, 20, 40, 80, 160, and 320 min; concentration: 10²–10⁵ spore m⁻³; Scopulariopsis brevicaulis: 5, 10, 15, 20, 25, and 30-min; concentration: 10³–10⁵ spore m⁻³ (six replicates for each sampling time). For each fungus, air concentrations were determined by a 15-channel optical particle counter (particle m⁻³; N = 36), microscopy (spore m⁻³; cyclone and filter, N = 36; Air-O-Cell, N = 18), culture (colony forming unit m⁻³; cyclone and filter, N = 36; N6, N = 18), and polymerase chain reaction (cell equivalent m⁻³; cyclone and filter, N = 36). Samplers were significantly correlated with each other as were the three analyses (correlation coefficients = 0.79–1.00 and 0.87–0.98, respectively). Ratios were calculated for simultaneous measurements with the cyclone and comparison samplers and for paired colony:spore, colony:cell equivalent, and cell equivalent:spore measurements for the cyclone and filter samples. The cyclone equaled or underestimated the other samplers for both fungi and all analyses (mean ratio: 0.75–1.04). A. versicolor colony and cell equivalent measurements exceeded spore measurements although microscopy should detect all spores not just culturable ones, perhaps due to difficulty observing the smaller spores or detection of DNA in cell fragments in addition to intact spores. Plots of the ratios of paired measurements against their averages identified biases between samplers and analyses. For example, ratios were correlated with spore concentration, and there was greater uncertainty at lower concentrations. These chamber tests have shown that the cyclone is suitable for collection of airborne fungal spores over a wide concentration range and time period and for analysis by microscopy, culture, and polymerase chain reaction.

Keywords:

• airborne fungal spores
• chamber study
• cyclone sampler
• method comparison
• sampler performance

ACKNOWLEDGMENTS

This work was supported in part by NIOSH contract HELD/EAB Can # 4927007U, Evaluation and Validation of a Novel Bioaerosol Personal Sampler Project. The authors thank Rob Miller, Dimon Pon, Zia Siddiqui, Jeff Wagner, Stephen Wall, Paul Wong, and the Facilities Management Services of the California Department of Public Health; William Hinds, University of California at Los Angeles; Tiina Reponen, University of Cincinnati; and Robert Gussman, BGI, Inc.

The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health.