Characterization of reaerosolization from impingers in an effort to improve airborne virus sampling.

AIMS To assess the impact of reaerosolization from liquid impingement methods on airborne virus sampling. METHODS AND RESULTS An AGI-30 impinger containing particles [MS2 bacteriophage or 30-nm polystyrene latex (PSL)] of known concentration was operated with sterile air. Reaerosolized particles as a function of sampling flow rate and particle concentration in the impinger collection liquid were characterized using a scanning mobility particle sizer. Reaerosolization from the impinger was also compared to that from a BioSampler. Results show that reaerosolization increases as flow rate increases. While the increased particle concentration in the impinger collection liquid leads to an increase in the reaerosolization of PSL particles, it does not necessarily lead to an increase in the reaerosolization of virus particles. Reaerosolization of virus particles begins to decrease as the particle concentration in the impinger collection liquid rises above 10(6) PFU ml(-1). This phenomenon results from aggregation of viral particles at high concentrations. Compared with micron-sized particles, nanosized virus particles are easier to aerosolize because of reduced inertia. Reaerosolization from the BioSampler is demonstrated to be significantly less than that from the impinger. CONCLUSIONS Reaerosolization from impingement sampling methods is a mode of loss in airborne virus sampling, although it is not as significant a limitation as the primary particle size of the aerosol. Utilizing a BioSampler coupled with short sampling periods to prevent high accumulative concentrations can minimize the impact of reaerosolization. SIGNIFICANCE AND IMPACT OF THE STUDY This study confirms reaerosolization of virus particles to be a mode of loss in impingement sampling and identifies methods to minimize the loss.