CO2 levels in more than 5,000 Quebec classrooms exceed province-set limit, data shows

Quebec considers a CO2 limit of 1,500 ppm in classrooms adequate.   (Ben Nelms/Radio-Canada - image credit)
Quebec considers a CO2 limit of 1,500 ppm in classrooms adequate. (Ben Nelms/Radio-Canada - image credit)

Carbon dioxide detectors in Quebec classrooms are recording higher levels of the gas compared to the fall, according to data released by the government.

Although most classrooms pass the air quality test, recent data posted on the Quebec government website shows that during the week of Dec. 19, 2022, the average weekly carbon dioxide (CO2) levels of all detectors was 930 parts per million (ppm).

In December, Education Minister Bernard Drainville presented a report showing that the air quality in 99 per cent of classrooms in Quebec was under the 1,500 ppm limit.

But the cold temperatures complicate CO2 concentration measurements, since windows are closed most of the time.

In the week before Christmas, 5,090 classrooms (6.7 per cent) exceeded the 1,500 ppm threshold.

The most recent data also shows nearly a third of classrooms (33.2 per cent) recorded an average weekly CO2 concentration of more than 1,000 ppm — the optimal limit according to Health Canada.

The data relates to 76,122 classrooms across 3,246 schools in Quebec.

During a news conference in early December, Drainville said that CO2 detectors have been installed in all Quebec classrooms.

In a string of tweets published Saturday, Drainville said 1.2 per cent of schools exceeded the 1,500 ppm limit. But government data available online does not specify the number of schools based on CO2 levels, only the number of classes.

Marwah Rizqy, the Liberal education critic, also pointed out on Twitter that the standard CO2 limit is 1,000 ppm, not 1,500 ppm. She said that, according to a committee of Quebec experts, a concentration exceeding this lower threshold is detrimental to educational success.

Needed improvements

It is impossible to compare CO2 levels for the week of Dec. 19, 2022 and the same period in 2021 because the province's website only displays data on air quality in classrooms as of Jan. 24, 2022.

But the data about CO2 levels points to a ventilation problem in those classrooms, says Stéphane Bilodeau, a lecturer in the department of bioengineering at McGill University and a member of the COVID-STOP collective.

"I don't think … it's worse this year than last year. But the results are more striking this year," he said.

CO2 particles and certain viruses, such as SARS-CoV-2 which causes COVID-19, circulate in the air, which creates a health risk, said Bilodeau, who is also an independent expert for the United Nations Office for Project Services (UNOPS).

"Now that we not only have the measurements [of CO2 concentration] and that we know that several viruses have airborne transmission, we must act," he said, adding that officials should not rely solely on opening windows to improve air quality.

Olivier Drouin, founder of the Covid Écoles Québec citizen initiative, agrees.

"[Opening windows] is not an option for many classes. Some don't even have windows to open," Drouin said.

There are inexpensive solutions to this problem, he added, citing the example of Corsi-Rosenthal boxes, a type of air purifier that can be built by anyone for a small fee. They can reduce particulates and viruses in the air — but not carbon dioxide.

Quebec has already invested some 400 million dollars to improve air quality in schools. An additional $225 million is planned for this year.