Red, we ventilate!
Funny boxes have appeared in school and university classrooms, and they could well multiply while SARS-CoV-2 is still circulating at a high level in France.
These CO2 sensors are used to measure air quality.
An indicator light comes on when it gets too bad.
Ultimately, the goal is to limit the risk of transmission of Covid-19.
"Several studies have established a link between the concentration of CO2 in the air and that in aerosols," explains Hélène Rossinot, public health doctor.
However, these large droplets potentially containing the virus can remain suspended in the air for several hours.
“The possibility of being contaminated depends on the concentration of virus in the air.
The more it is renewed, the more the risk of dissemination is limited, ”adds Jacques Haiech, honorary professor of biotechnology at the University of Strasbourg.
"Attention, it's time to open"
With 20,000 new positive people per day, it is not excluded to end up in the same classroom as a positive case.
Even if it is asymptomatic, it can transmit the virus.
Taken very seriously for a long time by scientific authorities, ventilation is now also taken by health and political authorities.
“It is necessary to ensure the regular renewal of the air in the premises with a supply of fresh air which should, if possible, be increased.
Continuous measurement of the carbon dioxide (CO2) concentration, using sensors, allows its quality to be judged, ”wrote for example the High Council for Public Health (HCSP) in an opinion issued in October latest.
“We focused a lot on the masks and the distance of one and then two meters, but ventilation is really essential.
And the CO2 sensors allow us to tell us: be
careful, it's time to open up,
”explains Didier Lepelletier, co-chair of the Covid-19 standing group within the body.
The HCSP recommends placing the alert threshold around 1000 PPM (parts per million).
"This thing" is a #CO2 sensor that we have been asking for months for #ecoles
The cost of 2 classroom chairs, to avoid betting everything on "open the windows like in the 19th century" @jmblanquer Finally on our screens, soon in our classes?
# CO2enClasse #COVIDisAirborne pic.twitter.com/OfRXdwJl5y
- School and Forgotten Families (@Ecole_Oubliee) February 5, 2021
The Ministry of National Education also recommends, henceforth, to "monitor the quality of indoor air, for example by CO2 sensors", but only in school catering areas.
Few establishments have started for the moment - contacted, the ministry refers to local communities.
In Heidwiller (Bas-Rhin), primary school rooms have been equipped since December, reports France Bleu.
In the capital, the Federation of parents' councils tells that a school in the 12th arrondissement carried out an experiment at the end of December.
On the side of the mayor of Paris, it is claimed not to have been associated with this kind of local initiatives, but plans to launch an action soon to promote these devices.
Mainly useful in winter
For several months, Bruno Andreotti has already been giving lessons in rooms equipped with a CO2 sensor.
This teacher in experimental physics at the University of Paris provides face-to-face practical work (TP) sessions.
"From the start of the school year on September 2, I worked on what had to be done to ensure health security, especially since it was not really supported by the institution", recalls t -he.
"The technique of CO2 sensors is perfected, we use them on our small scale to characterize the ventilation levels in practical work rooms", continues the teacher.
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Such tools would of course be less useful in summer, when the windows can be opened or the rooms ventilated almost continuously.
“There, with the cold, we obviously cannot leave open all the time.
But ventilating for 10 minutes when necessary, that would be really useful, ”Judge Didier Lepelletier.
Air "purifying" devices could also be used, but their effectiveness is not guaranteed.
"Given the principle of operation of these devices, the virus would only pass through and it would risk coming out without the treatment having destroyed it", explained Bruno Courtois at the end of December, expert assistance consultant on chemical risks to the National Research and Safety Institute (INRS).
A guide to making them
For doctors and scientists who promote CO2 sensors, such devices should not be reserved for schools.
Like the epidemiologist Antoine Flahault, many suggest using them in as many closed places as possible, and why not at home.
They can also be found for sale on e-commerce sites, for a few tens of euros minimum.
1/4 -If we want to promote a participatory approach to the fight against the # COVID19 pandemic, shouldn't we recommend that every adult equip himself with a CO2 sensor (quality standards) so that he can himself to assess the quality of the indoor air it enters?
- Antoine FLAHAULT (@FLAHAULT) November 21, 2020
The "La fabrique" laboratory of the Supélec engineering school even offers several tutorials for building your own sensor.
On social networks, the group regularly shares photos of devices sent to them by amateurs.
✅ "Homemade" manufacture of the @LaFabrique CO2 detector
☑️ Offering to the teacher 🎒 accompanied by its documentation 📒 https://t.co/4Blbf75YFa pic.twitter.com/0iGM661wcb
- Elodie Trinh (@Mintismycolor) January 26, 2021
Novices and tech-savvy refrain, of course.
But Hélène Rossinot imagines, for example, that technology courses in college or high school could be used to manufacture them, "with a view to both education and health".
“It would be a good opportunity to do something fun and useful to the faith,” she believes.