Invited from Europe 1 Thursday November 12, the LR president of the Auvergne-Rhône-Alpes region, Laurent Wauquiez, called on the government to deploy "
as quickly as possible to our schools, colleges, canteens, everywhere, from purification equipment
"to fight against the spread of the coronavirus in schools, where"
the students are piled on top of each other
".
“
Obviously, we have to install these devices.
[...] The virus circulates through the air, let's purify the air,
”he declared.
What do the specialists think?
Is this equipment a good strategy in the fight against Covid-19?
Read also: Covid-19: high schools are trying to adapt to distance learning
The purpose of air purifiers is to clean the air in a room.
They eliminate, or at least reduce, the presence of particles, chemical or biological pollutants such as viruses and bacteria.
There are several types, with different mechanisms.
A controversial effectiveness
Their use in the fight against Covid-19 is new and corresponds to the recent discovery of a possible transmission of the virus by aerosols present in the air.
Several German schools have adopted them in recent weeks, after studies carried out by the laboratories of the University of Munich.
Building on the example of Germany, the Auvergne-Rhône-Alpes region will also deploy air purifiers in its high schools.
A budget of 10 million euros should initially equip the canteens.
In 2016, a NASA study showed that purifiers equipped with HEPA filters (high efficiency air filters) were able to capture nanoparticles with a diameter of less than 0.01 μm (microns), up to 100% .
According to scientists from the French Society of Microbiology, coronaviruses have a diameter of between 0.08 and 0.2 μm.
They can therefore be absorbed by this type of purifier.
In a 2017 expert report, ANSES revealed similar figures.
“
Under the HEPA filter, the efficiency of the filter is at least 99.97%,
” it is written.
HEPA filter purifiers also have the advantage of not emitting ozone or other by-products.
As ANSES reminds us, certain catalysis, plasma or ozonation devices can show harmful effects.
The ozone emission by purifiers that use this technique can thus form polluting particles.
On the other hand, neither the NASA study nor the ANSES report mentions the effectiveness of air purifiers against coronaviruses, the question not being at the center of the news at the time. .
Caution at work
This is the argument that seems to retain the Minister of Education Jean-Michel Blanquer precisely based on the study of ANSES to signify his opposition to their deployment in French schools.
“We did a scientific study on these purifiers and it's absolutely inconclusive, based on everything we've seen.
On the contrary, it even seems that sometimes it sends the virus back,
”he said at the microphone of
France Inter
on November 2.
Read also: Covid-19: more and more high schools are switching into half-groups
For their part, scientists are cautious about their use.
Virologist specializing in emerging viruses and lecturer at the University of Montpellier, Yannick Simonin recalls that “
we do not know their effectiveness
” against Covid-19 and that “
more in
-depth
studies are needed
”.
If, however, their effectiveness is demonstrated, he considers that this solution "
could be used in all spaces where there is a high density of people [in order] to get rid of aerosols in the air
".
Yannick Simonin however brings nuances to these statements.
"
If it is effective, it is only on part of the transmissions
," he says.
Indeed, it will always be possible to be contaminated by droplets in the event of close contact with another person, or by touching an object on which the virus is present.
This is what leads the virologist to think that purifiers are "
not a quick fix
" but rather "
complementary
".
He then insisted on the need to "
ventilate the rooms regularly and keep the masks
".
