Evaluation of a high-volume portable bioaerosol sampler in laboratory and field environments Introduction Bioaerosols are diverse and complex particles of biological origin, including pollen, fungal spores, fragments of fungal mycelium, bacterial cells and endotoxins, viruses, protozoa, and fungal mycotoxins (Nevalainen et al., 1993). Exposure to airborne micro- organisms in indoor and outdoor environments can result in many respiratory and other adverse health effects, such as infections, hypersensitivity pneumonitis and toxic reactions (Burge et al., 1989; Karol, 1991). The allergenic, toxic, and inflammatory responses are caused by exposure not only to the viable but also to non-viable microorganisms present in the air (Gorny et al., 2002; Robbins et al., 2000). The exposure to airborne infectious agents (i.e. Legionella spp. and Mycobacterium tuberculosis), indoor allergens (i.e. Penicillium spp., Altenaria spp., Bacillus subtilis, Abstract This study investigated the physical and biological performances of a portable centrifugal sampler for viable bioaerosols, RCS High Flow. The per- formance of the test sampler in the laboratory and field environments was compared with that of a reference sampler, BioSampler. The laboratory experiments with non-biological particles of KCl, oleic acid, and polystyrene latex showed that the test sampler’s collection efficiency is about 22% for 0.5-lm particles, 48% for 1.0-lm particles, and approximately 100% for particles of 2.5 lm and larger. These tests indicated that the sampler’s cut-off size (d 50 ) was 1.1 lm. The test sampler’s physical performance when collecting the spores and vegetative cells of Bacillus subtilis var. niger (BG) was similar to that when collecting non-biological particles of the same size. In the laboratory tests, the RCS High Flow sampler was found to enumerate approximately 40% of BG spores and cells relative to the reference sampler, BioSampler. A similar ratio was found during testing in an indoor environment. This ratio decreased to below 10% when testing was performed in an outdoor environment. We hypo- thesize that the test sampler’s underperformance compared with the BioSampler could be caused by the damage to sensitive microorganisms during the collection process, test sampler’s sensitivity to wind direction and speed as well as break-up of particle aggregates during the impingement process in BioSampler, which resulted in more colony-forming units (CFUs) being counted by the reference sampler than by the test sampler. Overall, when the RCS High Plus is used to sample culturable airborne microorganisms, the results obtained may have to be adjusted to avoid potential underestimation of microorganism concentration in the air. H. R. An, G. Mainelis, M. Yao Department of Environmental Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ, USA Key words: Bioaerosols; RCS High Flow sampler; BioSampler; Collection efficiency. Gediminas Mainelis Department of Environmental Sciences Rutgers, The State University of New Jersey 14 College Farm Road New Brunswick, NJ 08901-8551, USA Tel.: 732-932-7166 Fax: 732-932-8644 e-mail: mainelis@envsci.rutgers.edu Received for review 17 November 2003. Accepted for publication 10 February 2004. Ó Indoor Air (2004) Practical Implications The laboratory testing of the RCS High Flow bioaerosol sampler showed that the sampler collects 1 lm particles and larger with an efficiency of 50% and higher; the efficiency reaches approximately 100% for particles of 2.5 lm and larger. When considering this result, most of the airborne fungal spores would be collected with an efficiency between 50 and 100%. The field testing, however, indicated that the RCS High Flow sampler recovered from 41 to 71% of microorganisms collected relative to the reference sampler, Biosampler, and this ratio dropped to below 5% during outdoor testing. Thus, while the RCS High Flow sampler offers certain advantages over other samplers for viable bioaerosols – it is lightweight, battery operated, and collects viable microorganisms at a high flow rate directly on agar media, the results obtained may have to be adjusted to avoid potential underestimation of microorganism concen- tration in the air, especially if sampling is performed outdoors. Indoor Air 2004; 14: 385–393 www.blackwellpublishing.com/ina Printed in Denmark. All rights reserved Copyright Ó Blackwell Munksgaard 2004 INDOOR AIR doi:10.1111/j.1600-0668.2004.00257.x 385