Collection efficiencies of four bioaerosol samplers (Andersen impactor, AGI-30 impinger, gelatin filter, and nuclepore filter) were evaluated for virus-containing aerosols. Four different bacteriophages were used as surrogates for the mammalian viruses. Results showed that the collection efficiency was significantly affected by the morphology of the virus particles. For hydrophilic viruses, the collection efficiencies of the Andersen impactor, impinger, and gelatin filter were 10 times higher than that of the nuclepore filter. For hydrophilic viruses, the collection efficiencies of all four samplers were 10-100 times higher than hydrophobic viruses. The infectivity of the virus in collected samples was also evaluated for an AGI-30 impinger. Results showed that the viruses retained more infectivity when the samples were refrigerated (up to 1 day) during storage than when stored at room temperature (up to 8 h). Therefore, even when refrigerated, airborne virus samples collected using an impinger should be processed as soon as possible to avoid loss of virus infectivity. (c) 2005 Elsevier Ltd. All rights reserved.