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Estimating Deposition of Viral, Bacterial and Fungal Aerosols in the Human Respiratory Tract: A Two Model Comparison
LYNN SECONDO, Jessica Sagona, Gediminas Mainelis, Rutgers, The State University of New Jersey
Abstract Number: 434
Working Group: The Role of Aerosol Science in the Understanding of the Spread and Control of COVID-19 and Other Infectious Diseases
Abstract
Modeling of the regional and total deposition of bioaerosols in the respiratory system might help in determining risk of disease development due to exposures. Computational models can provide estimates of particle deposition fractions for given breathing and particle parameters; however, most models have not focused on bioaerosols. We calculated deposition fractions in a reference adult with a recent bioaerosol-specific lung deposition model (BAIL) and with two multiple-path deposition models (MPPD) for three different breathing scenarios: “default” (subject sitting upright and breathing nasally), “light exercise”, and “mouth breathing”, keeping breathing parameters and bioaerosols characteristics the same for each scenario. The modeled species included: Bacillus anthracis spores and cells, Aspergillus clavatus and Stachybotrys chartarum fungal spores, and the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as individual virus particles, virus as aerosol, and virus as respiratory droplets. BAIL generally calculated higher deposition fractions in the extrathoracic region and lower deposition fractions in the alveolar region than the MPPD. Deposition fractions in the tracheobronchial region were similar among the three models; total deposition fraction patterns tended to be driven by the extrathoracic deposition fraction, with BAIL resulting in higher deposition in some scenarios. The extent of difference between deposition fractions calculated by BAIL and other models depended on particle size, with BAIL generally indicating lower total deposition for bacteria-sized bioaerosols. We conclude that BAIL predicts somewhat lower deposition and, potentially, reduced risk of illness from smaller bioaerosols that cause illness due to deposition in the alveolar region. According to BAIL, 16% of the SARS-CoV-2 virus will deposit in the alveolar region. On the other hand, it suggests higher deposition in the extrathoracic region, especially for light exercise and mouth-breathing scenarios. Additional comparisons between the models for other breathing scenarios, people’s age, and different bioaerosol particles will help improve our understanding of bioaerosol deposition.