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has begun to repeat itself around the world with more than 277 million cases and almost 5 and a half million victims. The decline in the effectiveness of vaccines over time has led many countries to proceed with a third and even fourth doses in an attempt to protect the most fragile and avoid infections even among those vaccinated.

Omicron is scary because it spreads extremely quickly and even if the health consequences appear to be milder (thanks to the large number of people vaccinated), hospitals are at risk of problems. Many infected do not know they are, and the chains of contagion are difficult to reconstruct with the exception of super-spreading events (Christmas dinners, school outbreaks).

Winter is still long and a lot of time will have to be spent indoors, where the virus spreads very easily.





, spacing, masks

: it has done everything in Italy and although deaths are much lower than a year ago, infections are older and more and more.

The virus kills less, but it is still with us


Can we still do something to get rid of it?

The fifth option is called ventilation

and now the World Health Organization also aims to communicate its importance and invites everyone not to miss an opportunity that could be victorious to mitigate the risk of infection in closed environments


We discussed this with

Luca Fontana

, a toxicologist, a technical officer at the World Health Organization who deals with engineering environmental controls for


treatment centers .

To understand how to combat it, we must first understand how Covid is transmitted: what is the main route of infection? "Sars CoV-2 is a virus that is transmitted through the air and the infection occurs through exposure to infectious respiratory fluids that are released as particles of different sizes during exhalation. While larger particles settle quickly,



remain suspended in the air for a longer period

. When people are in the immediate vicinity of an infected person, transmission It can occur by direct inhalation and depositing infectious particles on exposed mucous membranes.

Indoors poorly ventilated or crowded, these infectious particles can accumulate in the air and inhaled

: also as


proximity to the infected person, also increases aerosol concentration and, consequently, the risk of infection. Currently, there is limited evidence of transmission through surfaces (objects or materials that may be contaminated by viruses such as utensils and furniture) in the environment around the infected person

. "

Are vaccines not enough to defend ourselves?" Regardless of the mode of transmission,

vaccines help our immune systems protect us in serious ways

, but we know that the

impact on transmission is limited

They are effective in protecting us from serious illness and death, but they are not as capable of defending us against infection, so

the virus continues to circulate in the community

, although

many people remain asymptomatic

. With omicron, we are seeing an alarming number of reinfections. It is not a defeat for vaccines because they

maintain the crucial function of reducing pressure on the health system

, but

the circulation of the virus prevents us from regaining possession of our life

and it could favor the appearance of new variants. "What about masks?" How hand washing and other precautions help reduce the possibility of infection but not eliminate it. Surgical masks, but even more so FFP2, help

reduce the amount of aerosol inhaled

and prevent larger particles from settling on the mucosa, but they

do not eliminate the risk

with a high concentration of particles in the air and prolonged periods of exposure. They



be used correctly

and always indoors, which is not so often. We think of schools and offices where students and workers spend long hours. And also to other closed environments where for one reason or another we cannot wear the mask, such as restaurants. Outdoors,

the spray disperses

and dilutes

almost immediately

in the air, so very few infections are observed compared to closed environments. "Are there other ways out of the pandemic?" Continue with distancing, good hygiene practices, the use of masks, vaccination but undoubtedly increase the commitment to ensure the management of the risk of contagion also through adequate and adequate ventilation of the premises. Ventilation makes it possible to reduce the concentration of infectious aerosol in the air and thus reduce the risk of infection. But what does it mean to ventilate? It consists of bringing fresh and clean air from the outside to the inside and sending the exhaled air, together with the infected aerosol, to the outside. An important engineering measure for risk mitigation is controlled mechanical ventilation, but it is also possible to intervene with



, that is, opening the windows

. This second option, however, in addition to the

significant energy and environmental costs

due to heat loss,

does not allow any control over the effectiveness of the protection measure

. In recent years, following the example of indoor air quality problems, air


have also been developed

, that is, systems that filter indoor air to reduce the risk of contagion. Of course, they are not a permanent solution and ventilation is still the first option. A promising solution for

cost containment


personal ventilation

, or

air changes limited to the breathing area of ​​each subject when in a fixed position.

"But have not respiratory diseases always been fought with vaccines?" In general, respiratory disease or not, vaccines have been a great advance for the public health. Consider the

eradication of smallpox

and type 3 poliovirus, which, in fact, caused



However, history teaches us that the vaccine is not always the magic bullet

. Sometimes, environmental interventions were necessary to reduce or eliminate a disease. Interesting examples are cholera, yellow fever, and malaria.

In many countries, cholera has been eliminated through improvements in the water distribution system.

and in the sewer system. Yellow fever and malaria through rehabilitation works. It took years and significant investments, but today we no longer have cholera and malaria epidemics in Europe, for example. "Equipping a building with controlled mechanical ventilation is a great investment, will they offset the costs?" How much is this pandemic costing us? The

cost in human lives is simply incalculable

, a disaster. But in economic and social terms we can imagine what the costs are. Very high. Therapies, hospitalizations, indirect deaths of those who did not have access to medical care as well as all the economic activities they suffer and the stock markets that collapse: everything is paying the negative consequences of


. The pandemic has upset our lives, our economies and we must put ourselves in the order of ideas that

we will not get out of this situation in the short term

. We need a structural change in the approach to the pandemic,

we have to start thinking long term

. It is clear that

We cannot think of creating a controlled mechanical ventilation system in all buildings at night

. But it is

important to start

. We could start to evaluate the state of ventilation, improve it or reduce the occupation of spaces. And also

better communicate the importance of ventilation to mitigate the risk of infection

. Today we can see the list of allergens in any restaurant but we do not know if it is equipped with efficient ventilation: we must aim for that. No matter how high the initial investment is, it will still be acceptable when compared to future benefits.

It is then up to governments to decide whether and how to promote this change.

. After all, in Italy there is a 110% renewal bonus that is talked about a lot these days: why not include ventilation among the possible works? "Would ventilation bring additional benefits apart from Covid?" Respiratory diseases are the leading causes of death and disability in the world. Approximately 65 million people suffer from chronic obstructive pulmonary disease (COPD) and 3 million die each year, making it the third leading cause of death worldwide. Approximately 334 million people suffer from asthma, the most common chronic childhood disease that affects 14% of all children worldwide. Pneumonia kills millions of people each year and is one of the leading causes of death among children under 5 years of age.More than 10 million people develop tuberculosis (TB) and 1.4 million die from it each year.

Improving the quality of the air we breathe would bring enormous benefits to our lives

and could mitigate the risk of infection not only from Covid, but from all other acute and chronic respiratory diseases. "Is it possible to install a controlled mechanical ventilation system also in buildings historical? "I imagine that our fellow engineers will be able to help us in this but, even if it were not possible, we could always reduce the maximum occupancy of the rooms by adapting the number of people in the closed spaces to ventilation." Why has the WHO not communicated the importance of more incisive ventilation? "It is true that initially little emphasis was placed on airborne transmission outside of healthcare settings. To the

At the beginning of the pandemic, it was thought that the mode of transmission was through droplets

and that the aerosol had a marginal role. The issue has been the subject of much debate within the WHO, which however has always recommended ventilation and spacing as measures to mitigate risk. Unfortunately, to date we do not have a defined methodology to say if a pathogen is transmitted through the air or not and that is why

the scientific debate has been particularly heated.

"What is WHO doing now to promote ventilation?" We work with several experts since 2020 and some white papers have already been published. The "ventilation roadmap", for example, provides

concrete recommendations on how to improve internal ventilation

. Other important work is currently underway. For some months now, a working group made up of virologists, infectious disease specialists, engineers, architects, and physicists has been working on

how to quantify the risk of Covid transmission by air.

There are two projects: the first aims to create a

physical model to be delivered to governments from which they can orient themselves to develop ventilation standards in public environments.

At the moment, for example, in restaurants, ventilation should not only refer to odor and temperature control as is the case now, but a specific ventilation standard for infection should be introduced. The second project

is a tool available to everyone

thanks to which it will be possible to

calculate the risk of contagion


For example, if I wanted to organize a dinner at my house, I can enter the data with the size of the room, the number of guests, the existing ventilation or the size of the windows.

The tool will tell me what the real risk is in my home, it can advise me to limit the number of guests or it will tell me how long to open the windows each hour to mitigate the risk of contagion.

The model will need to be validated before it can be published and

we hope to make it available in the first months of 2022. "

According to the criteria of The Trust Project

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