Modelling Near-Field Aerosol Exposure for Respiratory Infection Risk Assessment

Quantitative microbiological risk assessment (QMRA) is a method to estimate the risk of infectious disease transmission from human exposure to pathogens. QMRA is a helpful tool to inform health policies to control the impact of infectious disease transmission from human-to-human transmissible infectious respiratory diseases. QMRA combines an estimate of pathogen exposure with information on the probability of infection given the dose. The infection risk of respiratory diseases is generally assumed to depend on the interpersonal distance between the infectious person (index) and the exposed recipient. To account for close-proximity exposure in QMRA, specific generic models are required. To be helpful in policy information, these models should be sufficiently accurate in describing elevated air concentrations of pathogens near the index. On the other hand, they should be sufficiently generic and flexible to be applied in generalized situations without requiring very specific and detailed situational information. In this work, we identified different models to account for near-field exposure in the literature: multizone, diffusion, and jet models. These methods were tested with respect to their applicability in QMRA. We evaluated them on the criteria of ease of use, the availability of parameter values for generic application, and their ability to describe air concentrations in realistic situations as replicated in experiments. It was found that only diffusion modelling appeared to be both flexible enough to describe experimental data and to be supported by sufficient information to allow for parametrization in a wide variety of situations. The multizone models were found to be easy to use but difficult to parametrize given the arbitrariness of aspects of the modelling method. The jet models were found to be more complex to implement and adapt to specific exposure scenarios.