We have been around for almost a year with the coronavirus. Since the World Health Organization ( WHO ) declared an international emergency for SARS-CoV-2 in January, studies have been carried out on its modes of transmission and, despite the reluctance of some authorities (the WHO itself included) Almost no one doubts that the main form of contagion of this coronavirus is through the air.
As the world expert in aerosols Jose Luis Jimenez has commented on more than one occasion, the WHO’s closure has no other explanation than the adherence to traditional paradigms such as the one that made it take decades to admit that measles was transmitted through the air .
The other explanation is that the idea of ​​diseases that travel through the air around us and remain in it is quite scary . It is much more controllable, so to speak, something that is deposited on surfaces and that you can clean in a moment. But if the only way to infect us was to touch something that an infected person has coughed on and then put our hand to our face , the spread of this virus would not be understood.
How to avoid infecting ourselves with the coronavirus
Once it is accepted that the coronavirus is transmitted through the air, the following problem arises: how to avoid infecting ourselves
The answer we already know by now, or should we: stay as little time as possible in closed and crowded places ,ventilate those spaces, keep a distance of two meters from others, wear a mask (better an FFP2) and use it well (well-covered nose and mouth, adjusted well over the nose, under the chin and on the sides and do not remove it when speaking) .
We already know all this, but in view of how we are, it is evident that we do not comply or, at least, we do not comply as a society . Almost a year after all this began, we continue, as a society, without realizing what we have on top of us, and it is enough to look at how others wear masks(if they have them) and how closed and crowded spaces are ventilated (it is striking that there are so few windows in hospitals) to fall into paranoia. In the face of this, we only have one thing left: protect ourselves and protect our own . And a useful tool for that purpose are HEPA filters.
HEPA filters
Well known to allergy sufferers, HEPA filters (high-efficiency particulate air) are a type of high-efficiency filter capable of removing very small particles (allergens, carbon dioxide, viruses…) and are usually included in vacuum cleaners. or air purifiers.
These latest appliances, air purifiers , are especially suitable for closed spaces with apoor natural ventilation (no windows, for example) or artificial ventilation (air conditioners that recirculate air instead of introducing fresh air from outside).
Although recommended, HEPA filters are not essential in well-ventilated domestic environments (open windows, with air flow) and with people without respiratory conditions or allergies. They are highly recommended in public and crowded environments where goodventilation cannot be guaranteed .
How to choose a HEPA filter
The popularity of devices with these filters and inquiries skyrocketed with the start of the school year, and in recent months that demand has not diminished. There are numerous devices with these filters for sale, both purifiers and humidifiers, but it is difficult to know which one we need.
The HEPA filter is a standard, so what we have to look at is the amount of clean air that the device in question produces. This parameter is called CADR (clean air delivery rate, clean air supply rate) and must be indicated on the product sheet as cubic meters per hour.
To find out how much clean air we need for a certain space (a classroom, a shop, a bar) we can use this HEPA filter calculator created by Fernando Lobato from a resource provided by Pablo Fuente, who has compiled a multitude of documents in this repository on the coronavirus, its transmission by aerosols and ventilation, among other issues.
In that calculator we enter the dimensions of the space in which we want to place the purifier and if its natural ventilation is good and it will provide us with the minimum CADR that we need. On that website there is also a list of recommended devices, but beyond brands or prices, we must look at the CADR, at the flow of clean air that we require to keep a certain environment as clean as possible of viruses (and contamination and allergens). in general).
And one more thing to keep in mind: HEPA filters are not a substitute for masks , two meters away or washing your hands. All of these security measures are cumulative.
