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Sampling efficiency comparison of four bioaerosol samplers and two particle counters

The bioaerosol sampler chosen by researchers for an experiment is often based on familiarity and availability. However, amongst the most popular general purpose samplers, is one more appropriate than the others for different sampling conditions? This project aims to examine 6 common samplers, in terms of their efficiency for detecting the total concentration and size distribution of airborne bacterium. All experiments were carried out in a mechanically ventilated, class 2 aerobiological test chamber. The chamber has a volume of 32 m 3 (4.20 m x 3.36 m x 2.26 m) with a 7.6 m 3 ante-room between the chamber and the laboratory. The temperature, humidity, ventilation rate and ventilation regime within the chamber were externally controlled. Background samples were taken with each sampler. Then a known concentration of either Staphylococcus aureus or Bacillus Subitilis was continually introduced into the centre of the chamber via a sixjet Collision Nebuliser (CN 25, BGI Inc, USA) at a flow rate of 8 L m -1 and a pressure of 12 psi. Once steady state conditions were achieved within the chamber, a second set of samples were taken with each sampler. The particle counters used included an Aerodymanic Particle Sizer (APS) Spectrometer and a Geo-α Handheld Laser Particle Counter. The biosamplers used include: a singleand a six-stage Andersen Cascade Impactor, an SKC BioSampler® Impinger and an All Glass Impinger (AGI 30).