AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
The Effect of Relative Humidity on the Viability of Airborne Bacteria and Viruses
KAISEN LIN, Aaron Prussin II, Eric Vejerano, Linsey Marr, Virginia Tech
Abstract Number: 90 Working Group: Bioaerosols
Abstract Many pathogenic bacteria and viruses have been isolated from air samples in different environments. These bioaerosols can be emitted not only by infected humans and animals but also by wastewater treatment plants, animal feeding operations, land application of biosolids, toilets, showers, and ultrasonic humidifiers. While being transported in the atmosphere, microorganisms may be subject to loss of viability. For improved understanding of the microbial ecology of the atmosphere and the transmission and control of infectious disease, it is important to identify the factors that affect the viability of aerosolized bacteria and viruses. Previous studies have demonstrated that relative humidity (RH) may affect microorganisms’ viability and infectivity. However, conflicting results have been reported. In this study, we investigated the influence of RH on the viability of gram-negative and gram-positive bacteria (E. coli and M. smegmatis) and unenveloped and enveloped viruses (MS2 and Phi-6) at RHs of 20%, 40%, 60%, 80%, and 100% in a custom rotating chamber. The microorganisms were aerosolized, kept suspended for an hour, and collected onto gelatin filters for determination of viability. Bacterial viability was higher under more humid conditions in general. Over 90% of E. coli survived after 1 hour of aging at 100% RH. The viability of E. coli decreased approximately monotonically with RH, while the viability of M. smegmatis was highest at 100% and 60% RH and was reduced at 80% RH. We expect to find different results with the viruses. Complementary studies of the physical and chemical composition of aerosols as a function of RH will help illuminate the mechanisms of inactivation.