Carbon dioxide levels at Mary Gardner school above 'acceptable level'

Some parents at Mary Gardner elementary school are concerned that higher-than-normal carbon dioxide levels detected in classrooms over the past six months could be affecting students' ability to learn.

Ventilation system failure at Mary Gardner school may be to blame for high carbon dioxide levels

Carbon dioxide levels in some classrooms at Mary Gardner School in Châteauguay were as high as 2612 ppm, more than double the acceptable level of 1000 ppm. (CBC)

Some parents at Mary Gardner elementary school in Châteauguay are concerned that poor air quality in classrooms could be affecting their children's ability to learn.

Carbon dioxide levels in some classrooms were found to be higher than the "accepted level" of 1,000 ppm (parts per million) in tests in November and April, according to the New Frontiers School Board. 

The November tests found most classrooms at Mary Gardner registered CO2 levels between 1,280 and 1,898 ppm. In two classrooms, the CO2 levels were even higher: 2,219 and 2,612 ppm, respectively.

A later test, on April 1st, showed an average of 1,012 ppm for all classrooms.

Tests conducted in November found that most classrooms at Mary Gardner registered CO2 levels between 1280 and 1898 ppm. (CBC)

"There are many schools that are going through the same problem right now," said Daoust. "It's an issue that we have to tackle."

Health Canada has set a long-term CO2 exposure level of 3,500 ppm, but the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) indicates a well-ventilated building should have CO2 levels of less than 1,000 to 1,100 ppm.

Not high enough for direct health impacts

Carbon dioxide can be harmful to human health, but only in much higher concentrations. 

According to Canada's National Collaborating Centre for Environmental Health, the lowest level at which CO2 has caused excessive acid levels in the blood (acidosis) is 7000 ppm, "and that only after several weeks of continuous exposure in a submarine."

But CO2 levels can be a good yardstick for how well air is circulating in a classroom.

In poorly-ventilated rooms, other chemical compounds, such as off-gassing from carpets and paint, can be irritating for students and staff, according to Robert Whiting, project scientist at the Canadian Centre for Occupational Health and Safety.

"This soup of chemicals can affect behaviour and can affect health to a certain extent," said Whiting. 

The Quebec Education Ministry told CBC in an email that it takes the test results seriously.

"While CO2 is not harmful to one's health, a concentration of more than 1,000 ppm can cause some people to experience problems concentrating or headaches," the ministry's statement said.

Debra Wright says her three children who attend Mary Gardner elementary school have been very tired recently and suffering from headaches. (CBC)
That's something that parent Debra Wright said she noticed in her three children who attend Mary Gardner school.

"She's been overly tired and seemed to have lost concentration from the beginning of the year through the winter months So, I had originally chalked it up to the winter blues," Wright said.

"But then, when it was mentioned CO2 levels were increased and based on my research, I think it might be a little bit more than [the winter blues.]"

Fan malfunction to blame

Officials said the problem appears to have been caused by an electrical malfunction that burned out four motors from the school's ventilation system.

Daoust said renovations to make schools more energy efficient have had the side-effect of making ventilation more difficult. Older schools used to have larger windows that could be opened to air out classrooms, but many of these windows have been replaced with newer models with smaller openings. 

"We've made our schools air tight and we have smaller windows to open," said Daoust. 

The school board installed two new, larger exhaust fans to replace broken ones at Mary Gardner school a few weeks ago.

Two more are on order and should be replaced this week, according to Daoust. 

Daoust could not confirm how much the repairs would cost, but said the school board, and not the Education Ministry, would be footing the bill. 


To encourage thoughtful and respectful conversations, first and last names will appear with each submission to CBC/Radio-Canada's online communities (except in children and youth-oriented communities). Pseudonyms will no longer be permitted.

By submitting a comment, you accept that CBC has the right to reproduce and publish that comment in whole or in part, in any manner CBC chooses. Please note that CBC does not endorse the opinions expressed in comments. Comments on this story are moderated according to our Submission Guidelines. Comments are welcome while open. We reserve the right to close comments at any time.

Become a CBC Member

Join the conversation  Create account

Already have an account?