Transport and dispersion of tracers simulating COVID-19 aerosols in passenger aircraft

Many laboratory experiments and model development activities have been underway to better estimate the risk of a person indoors becoming infected with COVID-19. The current paper focusses on the near-field (distances < about 5 m) transport and dispersion (T&D) of the virons, treating them as inert tracers. The premise is that the T&D process follows widely used basic analytical near-field formulations such as a slab model, a Gaussian plume model, or a diffusivity (K) model. A slab or Gaussian model is more appropriate for cloud sizes less than the distance scale of the turbulence, while a K model is more appropriate for cloud sizes larger than the distance scale. The proposed slab model is evaluated with observations from the TRANSCOM tracer experiment in Boeing 767 and 777 airplanes, which involved multiple release scenarios. Release rates of 1-μm plastic bead inert tracers were constant over 60 s from a mannequin's mouth and samplers were placed at about 40 nearby seat locations. A simple basic science near-field slab model is shown to agree with observations of maximum concentration and dose within a factor of two or three.