Airborne respiratory aerosol transport and deposition in a two-person office using a novel diffusion-based numerical model

Airborne Transmission of SARS-CoV-2: The Contrast between Indoors and Outdoors

“…These differences are summarised in Table 1, from which it can be seen that at multiple levels the behaviour of respiratory aerosols indoors is very different from that outdoors. By contrast, the behaviour of large respiratory droplets > 100 µm is broadly similar in both environments, with these generally not able to travel further than about 1.5 m. As such, this reinforces the consensus that COVID-19 is primarily spread by the airborne route via small respiratory aerosols, generally < ~20 µm diameter [23,91].…”

“…Figure 1 shows that susceptible individuals in the path of such aerosol clouds are more likely to inhale air with a higher viral concentration than those located far away from an infector. Furthermore, during near-field exposure, the size of the aerosol particles inhaled is likely to be larger than that in the far-field [91], with aerosol particles > 20 µm easily inhaled [23,62]. This is because, at close range, these larger aerosols, which generally settle out of the air over a few minutes, are inhaled before gravitational deposition can remove them from the air.…”

“…This is because, at close range, these larger aerosols, which generally settle out of the air over a few minutes, are inhaled before gravitational deposition can remove them from the air. By comparison, the chance of inhaling larger aerosols in the far-field is much less because these generally settle out of the air long before they can be inhaled [91]. Indeed, the evidence suggests that in the far-field, aerosol particles up to 10 µm pose the greatest risk [91].…”

“…By comparison, the chance of inhaling larger aerosols in the far-field is much less because these generally settle out of the air long before they can be inhaled [91]. Indeed, the evidence suggests that in the far-field, aerosol particles up to 10 µm pose the greatest risk [91]. Having said this, it should be noted that Coleman et al [35], in a laboratory study involving COVID-19 patients, found that 85% of the viral load was contained in fine respiratory aerosol particles (<5 µm) rather than in course aerosols, defined as ≥5 µm.…”