Comparison of the decay rates of aerosolized <i>E. coli</i> measured using different laboratory approaches for particle aging

Understanding the losses in pathogen infectivity that occur in aerosol particles is important to model transmission and inform the development of mitigation strategies. Previous studies have suggested that the losses in infectivity can result from multiple competing processes that may occur at different rates. The aim of the present study was to compare estimates of these losses measured using two different methodologies, specifically a rotating drum chamber and by the controlled electrodynamic levitation and extraction of bioaerosol onto a substrate (CELEBS). Comparisons were made using Escherichia coli (E. coli) across a range of humidity levels and particle sizes. The results demonstrate that both methodologies provide similar estimates of both a rapid loss of E. coli culturability that occurs immediately after particle generation and a slower decay observed in aerosol particles over longer periods of time. Both methodologies also observed that losses were humidity dependent, which is consistent with previous reports. While there are limitations to each measurement system, these results suggest that the two techniques provide complementary approaches for examining factors which may influence the survival of microorganisms in aerosol particles. While additional comparisons with a range of microorganisms across a wider range of environmental conditions and decay rates would be useful, the initial comparisons performed in the present study are important to help identify best practices for future studies and increase confidence in the accuracy and comparability of the generated data using the different approaches.<br/><br/>