What happens when a new coronavirus infected patient coughs in a crowded emergency room? A 3D video simulation created by researchers from the Bambino Gesù Pediatric Hospital in Rome, in collaboration with the university spin-off Ergon Research and the Italian Society of Environmental Medicine (SIMA), shows how respiratory particles of various sizes move in the environment and what is the impact of ventilation systems on the risk of contagion.
The air is our ally. The team recreated the waiting room of a pediatric emergency room equipped with a ventilation system, with 6 children and 6 adults inside without bezel (to be able to concentrate only on the effect of ventilation), and then tried to understand what happens in the 30 seconds following the cough in three different situations: with the ventilation system off, with the air at normal speed and with double speed ventilation.
The study confirmed that the correct use of ventilation systems is – together with the use of the mask – decisive in reducing the infection. Doubling the air conditioning flow rate (calculated in cubic meters per hour) has reduced the concentration of contaminated particles by 99.6%: the lower the concentration of SARS-CoV-2 coronavirus in an environment, the less likely it is to become infected .
How far does covid spread by air?
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Farther. The downside is that the double speed of the air favors the dispersion of respiratory particles in points of the room where with a switched off system or with normal activation they would not have reached. With the air conditioner off, people less than 2 meters away from the coughing child breathe 11% of large and small contaminating droplets (droplets and aerosols), while those 4 meters away are not reached at all.
With high velocity air, on the other hand, nearby people breathe just 0.3% of particles (because their concentration per cubic meter of air is much lower) but even those far away are reached, and end up breathing 0. , 08% contaminated aerosol. It is, however, as the authors write in the scientific journal Environmental Research, of a laughable concentration, perhaps even irrelevant to the contagion.
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