The Québec government and educational institutions are continuing to closely monitor the air quality in classrooms and ensure that appropriate mitigation measures are applied when problematic situations occur. 

The Ministère de l’Éducation (MEQ) has implemented a governance structure involving members of the school network and various bodies, such as the Ministère de la Santé et des Services sociaux, the Institut national de santé publique du Québec and the Commission des normes, de l'équité, de la santé et de la sécurité du travail. In addition, the MEQ is working closely with an independent expert in indoor air quality and industrial ventilation from the Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST). This expert is assisting the Ministère in the development of a strategy regarding air quality in schools in order to ensure that the best possible learning and working environment is provided at all times for students and school staff.

Measures implemented

Some of the measures implemented are as follows: 

  • development of a new protocol for ongoing digital monitoring of air quality in classrooms and identification of the required technological solution
  • acquisition comfort parameter sensors to measure carbon dioxide (CO2) concentration, level of relative humidity and temperature to ensure optimal air quality in all classrooms in Québec  
  • installation of these sensors in all schools
  • implementation of a program for maintenance of ventilation equipment and windows in summer 2021, which is ongoing
  • distribution and installation of several hundred air exchange systems within the school network
  • continuation of the program of required corrective measures to address problematic situations and adjustments to mechanical ventilation systems (that is, air evacuation systems and/or forced fresh air systems), such as:  
    • optimization of fresh air intake
    • removal of energy-saving measures
    • continuous operation of ventilation devices
    • replacement of air filters, use of more effective air filters if possible (MERV 13 or higher) and maintenance of ventilation systems, when required

The Ministère and the school network have been working together for several years and sharing their expertise to maintain good air quality in schools, especially by producing guides to best practices: 

The COVID 19 pandemic demonstrated the importance of continuously monitoring indoor air quality, especially in schools, and continuing to maintain safe environments for all occupants. 

The Ministère de l’Éducation would like to reiterate that the comfort and safety of students and staff school are its top priority. For more information on the opening of windows during cold weather, refer to the press release This hyperlink will open in a new window. (in French only).

Comfort parameter sensors

On September 10, 2021, the Ministère de l’Éducation announced that agreements had been reached with four companies, that is, Honeywell, Nova Biomatique, Assek Technologie and Airthings. They have supplied the estimated 90 000 comfort parameter sensors that were installed in all preschool, elementary, secondary, vocational training and adult general education classrooms in Québec.

This operation to allow for close monitoring of air quality in all elementary and secondary schools as well as in vocational training and adult education centres. Québec is the first government in Canada to implement a program of this type.  

Indoor air quality and the comfort of students are influenced by multiple factors, such as CO2 concentration, temperature and the level of relative humidity. Scientific studies show that an elevated level of CO2 in indoor air may cause students to be uncomfortable and affect their concentration and results, much like when the ambient air temperature is too high, for example. 

Real-time readings of three comfort parameters (CO2 concentration, temperature and the level of relative humidity) allow school staff to make changes more gradually and quickly in the affected rooms by, for example, adjusting the inflow of outdoor air.

Educational institutions can use the average data to take timely action when the set targets are not reached. 

School service centres and school boards can use the average data to identify trends and target buildings that require broader intervention plans and/or larger scale corrective work. 

This ensures that students and school staff are provided with best possible learning and working conditions in class.

The Ministère is working closely with the suppliers and the network to ensure the completion of this large-scale project involving more than 3 600 buildings and 86 000 classrooms.

Progress of the installation of comfort parameter sensors

In total, 90 000 comfort parameter sensors have been installed in preschools, elementary and secondary schools, and in vocational training and adult education centres. Of these, slightly more than 3 600 are sensors that make it possible to read the parameters outside the buildings. Approximately 86 400 rooms are equipped with comfort parameter sensors, in addition to the classrooms where sensors have already been installed.

The sensors are being installed in accordance with the established priorities:

  • Priority 1: Schools where CO2 concentrations over 2 000 ppm have been observed
  • Priority 2: Schools where CO2 concentrations over 1 500 ppm have been observed
  • Priority 3: Schools with natural ventilation
  • Priority 4: Schools with mechanical ventilation

Air exchangers

The Ministère has made available to school service centres, school boards and private educational institutions air exchangers that can be installed in classrooms where persistent air quality problems have been observed. Air exchangers are devices that filter out indoor air filled with CO2 and replace it with fresh air brought in from outdoors, thereby improving the indoor air.

Educational institutions are responsible for maintaining their classrooms and ensuring good air quality for students and school staff. It is up to them to request an air exchanger from the Ministère. The devices are delivered as quickly as possible.

Air purifiers

A multidisciplinary working group composed of scientific and technical experts was mandated by the Ministère de la Santé et des Services sociaux to study the issue of ventilation and the transmission of COVID-19 in educational and health care facilities. In its report published in January 2021, this group recommended that air purifiers not be used in classrooms.

The recommendation was based on the fact that these devices are unable to counter the transmission of COVID-19 through close contact with an infected person. In addition, they can impede the proper functioning of the ventilation systems in place and generate major air currents that can spread airborne particles over a longer distance.

These devices are not, however, capable of countering the transmission of SARS-CoV-2 through close contact with an infected person, which is recognized as the principal mode of transmission.

Furthermore, when there is satisfactory ventilation, these devices are useless and even pose potential risks as they could impede the proper functioning of the ventilation systems in place.

Lastly, they could generate major air currents that could create problems such as spreading more air-borne particles over a longer distance and altering air flows if a mechanical ventilation system is already installed.

Carbon dioxide (CO₂)

CO2 is a natural product of human respiration. Its presence in educational institutions has no effect on the health of the occupants but can have an impact on their level of comfort. For many years now, the Ministère de l’Éducation has been paying attention to this comfort and air quality indicator in order to ensure a healthy environment for students and promote their educational success.

  • In outdoor air, CO2 comes from different sources, especially the combustion of fossil fuels, and the concentration fluctuates at around 400 ppm. Indoors, CO2 essentially comes from the air the occupants breathe out, and the concentration is over 400 ppm.
  • Normal concentrations of CO2 in indoor air may vary depending on occupancy density, room volume, type of activity carried out, length of occupancy and ventilation efficiency.
  • An average weekly CO2 concentration under 1 500 ppm may be used as an indicator of satisfactory ventilation and ensures good comfort for occupants (preventing situations where, for example, students feel drowsy and have difficulty concentrating).
  • The Regulation respecting occupational health and safety This hyperlink will open in a new window. prescribes a maximum of 5 000 ppm for an 8-hour working day and 30 000 ppm for a short 15-minute exposure. This maximum limit for exposure in the work location is recommended by the American Conference of Governmental Industrial Hygienists.
  • CO2 is a comfort parameter and one of the air quality indicators. An elevated CO2 concentration indicates that the air is stagnant. The rooms concerned may require ventilation, especially the intake of fresh air.
  • Air exchanges with the exterior by natural means such as opening the windows or through mechanical ventilation are the main contributors to reducing the concentrations of this non-toxic gas in occupied indoor spaces. Air exchange is therefore one of the first actions recommended if an elevated concentration is observed in a room.

Management parameters

To ensure good interior air quality in educational institutions, the following must be taken into consideration: 

  • An average daily CO2 concentration below 1 500 ppm may be used as a parameter of satisfactory comfort. Moreover, the Direction générale de la santé publique confirmed its support for the use of this indicator in a letter of November 27, 2022.
  • The Ministère aims for a daily average concentration of CO2 of less than 1000 ppm in any room where instruction is provided.
  • A relative humidity level varying between 30% and 50%, depending on the season.
  • An ambient temperature varying between 20°C and 26°C.

The values measured in our classrooms and school buildings are well below the thresholds set by the CNESST in the Regulation respecting occupational health and safety. The actions taken in the classrooms are mainly aimed at increasing the comfort levels of students and school staff. 

General notice

Distinguish between carbon monoxide and carbon dioxide

It is essential to distinguish between these two gases, which have radically different effects on human health.

Carbon monoxide (CO): produced by incomplete burning of wood, hydrocarbons, etc., it is an odourless and colourless poison that can kill a human being, even in small quantities.

Carbon dioxide (CO2): produced by human respiration, it is a natural component of the air that poses no health risks at the concentrations normally found inside buildings.

Provincial data

For the weeks of March 6 to April 28, 2023, the provincial data shows that:

  • On average, nearly 96% of rooms recorded an average weekly concentration of CO2 lower than 1500 ppm, which is a sign of satisfactory air quality. 
  • On average, less than 1% of rooms recorded an average weekly concentration of CO2 higher than 2000 ppm.
  • On average, more than 96% of rooms had a satisfactory average weekly temperature (between 20°C and 26°C).

Based on the provincial data, it can be concluded that our classrooms have satisfactory air quality. 

Go to the Provincial data – Archives page to follow the evolution of air quality in our schools.

Explanatory notes

The data used to calculate the weekly averages of CO2, temperature and humidity are those recorded between 8 a.m. and 4 p.m., Monday to Friday. They do not include statutory holidays. However, the system does not automatically remove pedagogical days or snow days from the calculation. However, publications of the school service centres and school boards take this information into account as much as possible.

These numbers include data from both the public and private sectors.

For the moment, this data excludes most of the data gathered from wired sensors because these sensors do not transmit the information collected to the suppliers’ platforms. Further work on this issue is ongoing. Regardless, the sensors are installed and real-time data is available in the rooms. It should be noted that, in total, there are fewer than  7 000 of these sensors (under 8%), and that the vast majority are in schools with mechanical ventilation systems that do not pose any problems.

However, the effect on the final results, whether upward or downward, remains marginal.

CO2 concentration levels can fluctuate over the course of a day and from one day to the next. These fluctuations may be explained by various factors, including the outdoor temperature, which affects the opening of windows and doors, and the number of occupants in the room.

While it is entirely normal to have, on occasion, concentration levels above 1 500 ppm, it is abnormal for the situation to persist over a long period. The actions taken by the educational organization aim to respond to and quickly correct specific situations.

School staff know the instructions concerning the opening and closing of windows and doors, and regular reminders are sent out by the material resources departments. The results obtained to date show that when the actions called for under the guidelines to improve air quality in classrooms are carried out, they are effective in achieving the desired results.

Monitoring of educational organizations by the Ministère and publication of data

In order to provide information and transparency, the Ministère updates the provincial data at regular intervals. The data for previous weeks has been archived and can be consulted.

Educational organizations and private educational institutions are expected to make the data about their schools available. To consult this data, please contact them directly.

The Ministère strictly monitors educational organizations with rooms that have registered average weekly concentrations above 1 500 ppm. Educational organizations are encouraged to handle these situations by applying the established protocols in order to better manage the ventilation in these classrooms and maintain acceptable air quality. Solutions must be implemented by the educational organizations, which are responsible for managing and maintaining school buildings, particularly when persistent inadequacies, such as concentrations above 1 500 ppm for more than three weeks over a period of eight weeks, are detected in a room.

As such, here are the classrooms concerned for the period from March 6 to April 28, 2023:

Total number of classrooms: 73 900Weekly average above 1 500 ppm for three weeks or moreWeekly average above 2 000 ppm for three weeks or more

Number of classrooms 

1 147


Ratio (%) 



Number of schools 



Number of school service centres/school boards 



Number of classrooms with a recurrence from the previous period



The analysis of the eight weeks indicates that:

  • In total, 1 147 classrooms (1.6%) had an average weekly CO2 concentration above 1 500 ppm three or more times in the period.
  • In total, 57 classrooms (0.1 %) had an average weekly CO2 concentration above 2 000 ppm three or more times in the period.
  • Of the 1 147 classrooms, 383 (0.5%) had an average weekly CO2 concentration above 1 500 ppm during the last seven weeks of analysis in spring.
  • Among these, 29 classrooms (0.04%) had an average weekly CO2 concentration above 2 000 ppm during the last seven weeks of analysis in spring.

Status report on work completed and planned in the school service centres and school boards

Maintenance and upgrading work is being carried out continuously by educational organizations in order to provide healthy, comfortable and safe learning environments:

  • Since July 2020, $489.8 million has been allocated for this purpose. Investments in the amount of $138 million are planned from September 2022 to June 2023, for a total of $627.8 million. It should be noted that these amounts do not include the costs of the Ministère’s acquisition of air exchangers and comfort parameter sensors.
  • This work includes, among other things, the calibration of ventilation systems, the installation of air exchangers or implementation of other mechanical solutions, and the replacement or addition of windows that can be opened.

The report on the performance of indoor air quality control mechanisms implemented by school service centres and school boards (in French only) (PDF 708 Kb) is now available.

Three-party committee

A three-party committee (MEQ, CNESST-IRSST, MSSS-INSPQ) was created to oversee and authorize requests from the school network related to indoor air quality and to ensure better coordination of the action taken in this regard by the Ministère and the educational organizations. It provides a high-level perspective in the area of health and safety in learning and work environments.


Ministère de l’Éducation 

  • Martin Bérubé, Director, Direction de l’expertise et de l'innovation

Commission des normes, de l'équité, de la santé et de la sécurité du travail 

  • Caroline Monette, Engineer, Direction de la prévention-inspection - Rive-Nord 

Institut de recherche Robert-Sauvé en santé et en sécurité du travail

  • Ali Bahloul, Researcher, Prevention of chemical, biological, mechanical and physical risks

Ministère de la Santé et des Services sociaux 

  • Christian Roy, Direction de la santé environnementale 

Institut national de santé publique du Québec 

  • Dr Stéphane Perron, Physician specializing in public health and preventive medicine
  • Dre Caroline Huot, Physician specializing in public health and preventive medicine