UNDERSTAND EVERYTHING – Back to school under Covid-19: what is the benefit of CO2 sensors in schools? – BFMTV

CO2 sensors make it possible to know when it is necessary to ventilate a room, which is important information as SARS-CoV-2 is transmitted by aerosols, particularly in confined spaces. Explanations.

“Equipping schools and establishments with CO2 sensors is now recommended”, writes the Ministry of Education on its website. After a first recommendation last April, the government recommended for the start of the school year on September 2 the installation of carbon dioxide (CO2) sensors, and paves the way for potential funding. These tools make it possible to judge the need for class ventilation, an important parameter in the context of the anti-Covid-19 policy at school, while the Delta variant continues to spread.

“With regard to CO2 sensors, we encourage the generalization of their use and their use throughout the school system”, announced Minister of Education Jean-Michel Blanquer last week at a back-to-school press conference.

• How do CO2 sensors work?

These detectors placed in a room make it possible to measure the concentration of CO2 in the air and to judge the need for ventilation, they “act as ‘thermometers'” of CO2, explained Jean-Michel Blanquer. In an April 28 report, the High Council for Public Health recommends to “implement aeration actions and ensure the proper functioning of ventilation when the concentration exceeds 800 ppm of CO2”.

This tool was already used in some schools in France, in order to assess pollution, but also in Germany and England to try to control the Covid-19 epidemic.

The sensors “measure the quality of the ambient air and report the result in real time thanks to colored indicator lights: green, the air renewal is good, orange, it is advisable to ventilate, and red, it is necessary to ventilate “, explains Lille town hall on its website. “Their deployment makes it possible to raise awareness of good practices, and to strengthen health security conditions in schools”.

We know that the virus is transmitted by aerosols, and more easily in closed spaces. The measurement of CO2 does not allow to directly assess the presence or not of SARS-CoV-2, but “it is a tool which will allow us to tell us if the conditions are favorable for the circulation of the virus”, explained at BFMTV Lille Charlotte Brun, assistant to Lille town hall, in charge of Education.

• Is it effective in the fight against Covid-19?

Ventilation is one of “the key elements that have enabled us to get through the crisis so far and to have the objective of opening schools,” said Jean-Michel Blanquer. However, “the CO2 sensor is obviously not central in the health crisis management strategy,” he said, “what is most important is above all to open the windows more often. possible”.

On August 19, doctors and teachers were alarmed in a column published in The world lack of measures in schools as the Delta variant continues to spread. “Windows must be opened much more frequently and the recommendation to equip establishments with CO2 detectors cannot be enough: this must be the rule”, they demanded. Several teachers’ unions also demanded that this measure be generalized since last spring.

For the APPA (association for the prevention of atmospheric pollution), the medical biologist Fabien Squinazi piloted a scientific report published in June recommending “aeration and ventilation” natural as “key principles” to ensure optimal air quality. In short: open the windows for ten minutes every hour to bring in fresh outside air.

“Vaccinate, test very regularly: these are the only two ways [d’endiguer l’épidémie]. If washing your hands, wearing a mask and ventilating were enough, we would have controlled the situation for a long time and would not be in the mess we are in today, ”said epidemiologist Catherine Hill to The Obs.

Social distancing, barrier gestures, and the practice of testing or vaccination for people over 12 years old therefore still remain at the heart of anti-Covid-19 prevention in schools. The CO2 detector is currently used as an additional tool to these other measurements.

• Will all classes be equipped at the start of the school year?

While some areas had started to equip themselves with sensors before the end of the 2020-2021 school year, not all classes will be equipped with them when the students return on Thursday. In Cannes (Alpes-Maritimes), “the 230 classes of the 32 municipal schools and the 10 Cannes nurseries will all be equipped” with detectors but also with air purifiers at the start of the school year, ensures the town hall on its site.

“It is too late to launch such equipment plans” declares for her part to BFMTV Delphine Labails, mayor of Périgueux (Dordogne) and president of the education commission at the Association of Mayors of France. “On the other hand I believe that neither we, nor the elected officials, nor the services of the State thought that the virus would evolve in such a way, that we would be confronted with such an epidemic peak on this re-entry, and perhaps that we lacked a little vigilance and anticipation “.

The Occitania region assured BFMTV that CO2 sensors had been installed in all high school canteens, which represents 225 detectors in total. In Île-de-France too, CO2 sensors are installed in all high school canteens. These school catering places have been singled out several times as being places of contamination.

The cost of these sensors – between 150 and 200 euros per unit – prevents some establishments from obtaining them. It is in fact the responsibility of the local authorities, and not all of them can support the financing. “In the middle of the year, the budget was made and it is difficult to find additional resources”, explains to France Info the mayor of Offemont (Territoire de Belfort), a small town of 4000 inhabitants.

“The modalities have not yet been defined but what we know is that in the territories where it will be necessary, the State should accompany us to buy these tools”, explains Delphine Labails. “We are working with local communities so that in case they have financial difficulties to make this acquisition we can help them” assured his side Jean-Michel Blanquer.

• What about air purifiers?

The issue of CO2 sensors is often discussed with that of air purifiers, which would allow the air in a room to be renewed without opening the windows. For epidemiologist Antoine Flahault, air purifiers must be added “if the windows cannot open,” he told AFP. But the government remains for the moment measured on this subject, even if several schools have already provided them.

“Regarding air purifiers, the health authorities have always asked us to exercise good judgment. Nothing replaces the fact of opening the windows”, explained Jean-Michel Blanquer in the JDD. “These air purifiers can be especially useful for certain rooms which cannot be ventilated sufficiently through the windows”.

To get out of the imbroglio, the deputy Matthieu Orphelin (EELV) claimed at the end of August the establishment of an “action committee for an air quality strategy – Covid in schools” associating all the actors concerned: teachers, parents, directors, doctors, experts in the quality of air or community representatives.