April 20, 2021 – Press Release from the Government of Québec

Qualité de l’air dans les écoles
Résultats et correctifs apportés en lien avec l’exercice de mesure des taux de CO2

March 22, 2021, Update – CO2 Sampling

As you know, we recently carried out carbon dioxide (CO2) measurements in all our schools and centres to ensure air quality. The result of the CO2 measurements, which have also been sent to the Ministry of Education, can be viewed by visiting each of our school web pages (Blog – Reports), or you can click here to view the full document.

It is essential for us to ensure the quality of the air in our establishments. The health and safety of students and staff is our top priority, especially at this exceptional time. Therefore, the tests were carried out according to ministerial directives, to adequately measure the level of carbon dioxide in our premises, which gives a good idea of ​​the air quality.

Analysis procedure

For each of the classes identified, the CO₂ level was measured three times during a period of the class, namely before and at the middle of the class. The third measurement was taken after opening the windows or the door for a period of 20 minutes. Although the Department of Education considers CO2 concentrations below 1500 ppm acceptable, school boards are encouraged to take measures to aim for the target of 1000 ppm, established by Health Canada as the comfort level. Action must be taken quickly when concentrations exceed 1000 ppm and within a week, when they reach 2000 ppm.

The identified classes were chosen in order to represent the overall portrait of the school according to the configuration of the classes (orientation in relation to the wind and the sun, the floor on which it is located, number of windows, type of ventilation, etc.) as well as according to the occupants of the class (school level, number of occupants, etc.).

Actions taken locally

In order to ensure optimal air quality in the classrooms, all have been asked to apply the prescribed measures.

In the case of schools and centres with mechanical ventilation, material resources have ensured its proper operation and efficiency. In the case of schools and centres with natural ventilation, the opening of windows and doors is applied to ensure the renewal of air.

In addition, each school has been equipped with a portable CO2 measuring device. This equipment allows the school team to monitor and validate the actions implemented, if necessary.

All the health measures put in place to curb the spread of COVID-19 also help to ensure the health and safety of all.


On January 13, 2021, we received new directives from the MEQ asking all school boards and service centres to continue with the CO2 levels sampling in all our buildings.

For each building, measurements will be taken with the same procedure in four to ten classes. Classrooms will be chosen so that they are representative of the entire school (different orientations in relation to the wind, different grade levels, different floors, different dates of construction, etc.). So corrective actions, if any, can be applied to similar classes. In the same school, if possible, measurements will be taken in the morning and in the afternoon.

Along with CO2 level measurements, the relative humidity and temperature measurements will also be taken.

The above parameters will be measured whether the room is mechanically or naturally ventilated.

If at the end of the exercise, the CO2 level measured in a naturally ventilated classroom exceeds the value of 1000 ppm, the teacher and the administration responsible for the building will be advised to open the windows more regularly.

In a mechanically ventilated classroom, if the measured CO2 level exceeds 1000 ppm, an inspection of the ventilation system will be made and corrective measures are taken to improve the situation, for example by increasing the flow of fresh air.

Once the corrective actions are in place, C02 measures will be taken again to ensure their effectiveness.

All the measurement and corrective action exercises will be carried out in close collaboration with the school principals and should be completed by the end of March.


In order to document the possibility of transmission of COVID-19 by aerosols, the Ministère de l’éducation du Québec (MEQ) asked us to proceed with the air sampling to establish a portrait of carbon dioxide (CO2) concentration in our classrooms.

More specifically, we are undertaking measurements of the carbon dioxide (CO2) level, in a representative sample of the school board buildings in order to ensure that the CO2 concentration in the air of classrooms complies with applicable standards. The level of CO2 is an indicator of the intake of fresh air in a room. A high intake of fresh air indicates proper air circulation and aerosol dispersion.

To ensure the quality and uniformity of the tests that will be performed a procedure has been set out by the MEQ and will be followed by all school boards and service centres in Québec.

The schools are selected according to set parameters so that Elementary, Secondary, and Centres will be sampled and that schools with natural and mechanical ventilation will also be sampled. Not all schools will be visited, but it will reflect the majority of situations in the school board.

In each designated school, at least 4 classrooms will be tested at 3 different times, namely prior to students’ arrival, after 20 minutes of teaching activities, and after opening the windows, in order to get a full portrait.

Should any deviation in the CO2 level from the applicable standards be identified, corrective measures will be implemented board-wide to address all situations in similar circumstances.