QUEBEC CITY -- Three quarters of Montreal-area classrooms tested as part of a small "secret project'' show significant ventilation issues favouring COVID-19 transmission, a group of doctors and experts has found.

The COVID-STOP group recruited 12 teachers to test the air in 25 classrooms and premises in Montreal-area schools with machines commonly known as CO2Meter and CO2Mini.

In three out of four classes tested in secret, ventilation was problematic and CO2 levels exceeded the acceptable level of 700 to 800 ppm, the group revealed in a statement Wednesday.

In some classes, the rates rose to more than 2,100 ppm.

International specialists, including José Luis Jimenez from the University of Colorado, recommend a maximum concentration rate of 650 to 800 ppm, said COVID-STOP.

“Imagine the scale of the situation if we tested the classes assiduously with real experts,'' said internist Marie-Michelle Bellon. “With the freezing cold that will soon make it impossible to open windows, we are worried that schools will fuel the pandemic even more.”

According to Quebec Solidaire (QS) spokesperson Gabriel Nadeau-Dubois, the study proves that the opposition is right to call for CO2 detectors and portable air purifiers in schools.

Nadeau-Dubois accused Education Minister Jean-François Roberge of not taking the issue seriously at a press briefing Wednesday at the National Assembly in Quebec City.

"The government brushed it off, practically laughed in our face,'' he said. “We were right. The quality of the air in the classrooms is worrying."


In a statement to CTV News on Wednesday evening, the education ministry said more news is coming and it expects it to be more reassuring.

"We will soon unveil the report requested from the school network on ventilation in our schools," the ministry said.

"We are confident that the vast majority of schools have already complied with the requirements. If this is not the case for some of them, we will do all the necessary follow-ups with the school service centers so that the schools concerned can be done quickly."

It also said that provincial authorities are "strongly encouraging" the schools "to take advantage of times when students are away from school, during the holidays, for example, to do the work."

The province said that it had asked public health bodies to make sure their guidelines are up to date.

"The Minister of Health, Christian Dubé, asked Public Health and the INSPQ to re-evaluate their position with the help of experts and scientists," the statement said.

"If there are new recommendations issued by the INSPQ, we will take the necessary steps to have them applied."

Montreal's director of public health, Mylene Drouin, also responded to the news during a news conference Wednesday.

"It wasn't a surprise and the government is working on this specifically," she said. 

This report by The Canadian Press was first published Nov. 25, 2020.

--With files from CTV News Montreal