Airborne Microorganisms. A methodology to examine viability of bioaerosols

Abstract: Transmission through air is a major pathway for spreading of diseases, but much about the process and survival of airborne microorganisms is still unknown. Epidemiological studies investigating the spread of diseases can only yield information on a population level. In order to find out which parameters affect the survival of microorganisms, controlled laboratory studies are required. The aim of this thesis was to construct and validate a setup for generation of airborne Pseudomonas syringae and Norovirus. The setup consists of a sparging liquid aerosol generator (SLAG), an exposure chamber with a controlled environment and a liquid impinger (BioSampler) which samples into a liquid fluid. Bacterial samples were analyzed with flow cytometry and virus samples with polymerase chain reaction (PCR) to determine quantity and viability. P. syringae was aerosolized and exposed to a relative humidity of 25 % and 60 %, with a measured survivability of 58 % and 40 %, respectively. Norovirus was aerosolized and collected in a concentration sufficiently high to allow for quantification with PCR. Throughput of the system, i.e. final concentration versus initial concentration in the sample, was measured to be 0.2 % for both P. syringae and Norovirus. In conclusion, experimental confirmation that controlled laboratory studies on bioaerosol can be performed has been obtained. Optimization to increase the throughput of the setup has been suggested and include: parameter optimization of the generator and possible changes to instrumentation. Future research prospects with the presented method are studies on spreading of diseases and toxicological studies.