Engineer Buonanno from the University of Cassino: The virus is transmitted by air in closed environments. We are able to secure the air, regardless of the variants, as has already been done with water. Ventilation, emission reduction, management of exposure times and crowding can mitigate the risk of infection
Why is the pandemic curve uphill again after the summer slowdown?
Essentially for two reasons. Vaccines are a necessary but not sufficient protective measure. They have the ability to reduce the disease above all compared to contagion and for such an infectious variant as the Delta they are fundamental to respond Giorgio Buonanno, Professor of Environmental Technical Physics at the University of Cassino and at the Queensland University of Technology of Brisbane in Australia. The effectiveness of vaccines is reduced in considerably shorter times (3-4 months) than the time needed to vaccinate the population (9 months), making it practically impossible to always have the right timing between high percentages of immunized in coincidence with a high incidence of the virus. As a result, we are always forced to chase the waves of the virus passively.
And the second reason?
Pandemic growth the direct consequence of a basic error committed since the beginning of the pandemic by health authorities on how the virus spreads. As now underlined by numerous scientific studies, and also admitted by the World Health Organization, the dominant mode of contagion not related to droplets emitted by those who cough or sneeze and which quickly fall to the ground, but the air transmission, in which the virus travels inside very small droplets (the famous aerosol), able to float in the air. One can imagine the analogy between an infected person and a smoker: the aerosol will behave similar to cigarette smoke.
How can we defend ourselves from smoking?
Protective measures should be completely different between open and closed environments. In the open ones it is enough to stay spaced (over one and a half meters) if the exposure time is high (for example during an aperitif or outdoor dinner), without any need for masks. Even if you are in situations of unavoidable crowding, the risk of becoming infected is negligible if the exposure times are very short (for example if I walk in a crowded pedestrian street). Instead in the closed environments the risk is much higher because the “smoke” remains in the closed environment and we are very likely to inhale a dose sufficient to infect us. In this case, the surgical mask guarantees reduced protection unlike the FFP2 /N95
Isn’t the third dose of vaccine enough?
The third important dose for regain the immunity of people who got vaccinated more than 5 months ago. And this number of people far exceeds those who do not intend to get vaccinated. But it will take months, and the virus has started to run again in Italy too.
Can the risk be mitigated indoors?
IThe risk of infection can be estimated and mitigated with engineering interventions. This is because the competences of the “journey” of the virus from the generation of droplets, the subsequent emission, evaporation and aerial transmission, deposition in the susceptible subject are physical processes, unknown to the medical area. In itself the problem similar to that ofindoor pollution: we know that the smoke from a cigarette, a candle, a cooking activity are harmful to health but to protect ourselves at home we turn to engineers who suggest specific technical solutions such as extractor hoods or ventilation to solve the problem. Today with the engineering techniques possible estimate the risk of contagion as a function of a scenario in any closed environment (means of transport, offices, schools, cinemas) and consequently take action to reduce this risk with the emission reduction the viral load of the infected subject (for example with the adoption of microphones for teachers in schools), the management of exposure times, crowding, the introduction of ventilation. All this regardless of the variants: engineering technology works on all strains and on all pathogens, not just the coronavirus.
What is meant by ventilation?
It means dilute internal pollutants or pathogens with clean external air. Ventilation can be either mechanical than natural (in the latter case we speak of ventilation). Mechanical ventilation is more expensive but allows you to keep air changes under control. The natural one is free (excluding the energy costs of keeping the windows open) but it is not easily controlled. Hybrid solutions involve purifiers or CO2 sensors to control natural ventilation. Today we have the skills to start one technical revolution based on our scientific knowledge able to control indoors the comfort, energy saving, pollution and the transmission of pathogens, and not just in new buildings. a revolution but the only lasting way from the variants already announced and from all respiratory pathogens.
You see a lot of advertisements for air purifiers. How reliable are they? What do you need to be careful of in order not to risk buying useless tools?
The reliable principle of purifiers is based on filtration (generally HEPA filters). But the fundamental parameter is the flow rate of treated air compared to the volume of the closed environment. The optimal value cannot be defined absolutely but depends on the knowledge of the risk and other mitigation measures. Often even the best ventilation is not sufficient to mitigate the risk in closed environments, so a mix of solutions must be used which also includes, as already mentioned, vaccinations, masks, management of crowding and residence time.
Do you think it is really possible to secure the air?
The water that comes out of our taps is clean. We take it for granted, but two hundred years ago cholera was spread right through water. Since then, with the engineering approach we have made “water safe”. Today we are ready to do the same thing for the air too: everyone has the right not only to clean water, but also to air free from pollutants and pathogens. a right of citizens and a duty of managers of public environments.
How will our Christmas be compared to last year?
I hope it is at least similar. Despite a much more infectious variant, we have mitigated with vaccination but we have done nothing to combat contagions in closed environments. Without a radical change which provides for the adoption of pharmacological measures only (vaccination), and excludes non-pharmacological but engineering measures (risk estimation, ventilation, management of environments), we will always live with the nightmare of winter and the dream of summer.
November 27, 2021 (change November 27, 2021 | 16:08)
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