A novel laminar-flow-based bioaerosol test system to determine biological sampling efficiencies of bioaerosol samplers

In this work, we describe a novel type of bioaerosol test system based on a laminar airflow chamber that provides a homogenous aerosol of microbial cells with known concentrations and defined culturability to bioaerosol samplers positioned in the chamber. In the system, three control and monitoring points (CMPs) are implemented in which the number and culturability of microbes can be determined by combining optical particle counting with microscopic and culture-based microbiological analyses. This lineup is designed to quantify the biological sampling efficiency (BSE) of a bioaerosol sampling device. Seven bioaerosol samplers were tested with four fungal and one bacterial species and their BSEs have been determined under optimized standard operating conditions. After executing tests with the appropriate statistical power, this new laminar-flow platform demonstrated the sensitivity necessary to determine significant differences in the recovery efficiency of viable fungal spores and bacterial cells in modern samplers. Under these test conditions, the samplers showed considerable differences in BSEs for the individual fungal and bacterial species. Our data demonstrate that a large number of experimental repetitions and measurements under tightly controlled and monitored conditions are necessary to quantify the BSE of a given sampler and to compare them to each other. Employing this system improves biological evaluation of samplers because natural environments are not suitable for this task due to their high variabilities in homogeneity and distribution of cells as well as fluctuations in culturability ratios. © 2019 American Association for Aerosol Research