In September 2023, Heather Pun started sending her son to school with a carbon dioxide monitor. He was spending his days in a stuffy portable classroom, and she worried that COVID was being passed lung-to-lung through the stale air.
The device, which reads the concentration of carbon dioxide (CO2) in the air, showed CO2 levels as high as 3,500 parts per million (ppm) in his classroom.
Federal guidelines say levels should be below 1,000 ppm. At 1,400 ppm, the ability to do complex strategic thinking may be cut in half, since less oxygen is reaching the brain.
“3,500 ppm is just not a healthy environment for children to be learning in,” Pun tells me.
CO2 levels also give a sense of how well ventilated a room is. Poor ventilation causes airborne illnesses to linger in the air, which spreads infections quicker.
Today, Pun is a member of Clean Indoor Air Toronto (CIATO), a group of parents and community members who got together in 2024 to push the city to test and clean indoor air.
Buildings are supposed to comply with ASHRAE Standard 62.1, which is the ventilation standard in the Ontario Building Code. But CIATO members say that most buildings are never checked after construction, and many end up falling short.
That includes public schools.
The Toronto District School Board (TDSB) received $81.6 million in federal and provincial funding for pandemic-related upgrades. The money was used for retrofitting old HVAC systems, buying portable air purifiers and building outdoor seating areas. The TDSB posted a report online showing what measures each school is taking to clean the air.
But CIATO raises concerns.
Though TDSB classrooms have HEPA (High Efficiency Particulate Air) filters, multiple parents say those aren’t being used and are just gathering dust.
“They’re turned off because they’re noisy. They’re pushed into a corner so that airflow is being blocked into the air purifier. Or they’re just being used as a piece of furniture, with stuff piled on top,” says Louise Hidinger, a biochemist, a member of CIATO, and a mom of two kids in the TDSB.
When she’s gone in for parent-teacher interviews, Hidinger has seen the classroom’s air purifier sitting unplugged in a corner.
She says teachers need quieter HEPA filters, education on why they are important and tips for how to use them. For example, the units should be placed near the middle of the room to maximize air flow.
But with no plan to regularly check air quality in buildings, it’s hard to say if schools are any safer than before.
The TDSB’s website notes that “the TDSB is installing CO2 sensors and occupancy sensors on new ventilation equipment, to monitor fresh air delivered to the school and occupancy levels.”
But CIATO members say every classroom needs a CO2 monitor. It doesn’t matter if a CO2 monitor in a school’s newly-built gym shows the air quality is great. If the air quality in classrooms – where students spend most of their time – is bad, they’ll still get sick.
It’s been done elsewhere. In Boston, the school board installed air quality monitors in every classroom, and built an online map showing each classroom’s air quality.
More than COVID
“We understand why many educators and families don’t think about COVID anymore,” says Mary Jo Nabuurs, a member of Ontario School Safety. “No one in leadership is overtly discussing stuff like this, right?”
“If no one’s telling you, then of course you’re not going to think it’s a big deal.”
But while people in power ignore COVID, kids are still getting really sick. And clean air is a simple solution.
“One of the really frustrating things of this [pandemic] is how it’s been painted as something mild. And it’s not,” says Hidinger.
After her son got COVID in 2023, he was left with symptoms that lingered for four or five months. He had shortness of breath and developed a sensitivity to light, sound and scents. He also had a constant headache that would get so bad he vomited. She says his health is “always a constant worry in my mind now.”
Besides stopping the spread of COVID, clean air means less airborne disease and pollution, period. A spate of other illnesses – measles, influenza, RSV, bird flu – also spread through the air.
“We’ve known for decades that schools are horrible places for air quality,” says Nabuurs. “But nobody’s ever just given it very much attention. COVID shone this massive spotlight on just how crucial it is.”
Keeping kids safe
In January, Clean Indoor Air Toronto got Toronto Public Health to send TDSB schools updated infographics about how to stop the spread of respiratory infections. Still, the grassroots group struggled to make sure the infographics weren’t buried or ignored by schools.
In January, when the city was deciding on its 2025 budget, CIATO sent a letter to Mayor Olivia Chow. They had three asks: make a city-wide indoor air quality policy and bylaw, create a program to upgrade air filtering systems in Toronto’s buildings, and monitor CO2 levels in all city buildings and schools.
None of their requests were included in the budget.
The group fights for clean air in schools, Nabuurs says, so that kids can get back to learning even if pandemics become more frequent.
“Let them be kids,” she says, “and let the people and the structures around them be set up so that everybody can be as safe and healthy as possible.”
This article appeared in the 2025 April/May issue.
