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A HEPA-filtered ventilation system is assembled at Saint-John Fisher Senior Elementary School in Montreal on Dec. 1, 2020.

Andrej Ivanov/The Globe and Mail

Despite expert consensus that tiny airborne particles help spread COVID-19 indoors, many Canadian school boards are doing little more than opening windows to air out classrooms that lack central ventilation systems.

A handful of large school boards have installed portable air cleaners, but such actions to reduce transmission risk in classrooms without mechanical ventilation are rare, including in some of the country’s worst COVID-19 hot spots.

The Globe and Mail contacted 26 of the largest Canadian school boards from coast to coast to find out what steps they have taken to improve ventilation, manage windows, test classroom air quality and install air purifiers to combat the spread of the coronavirus within their walls.

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Many school boards are relying on teachers to open classroom windows – come sun, rain, snow or 30 below.

Increasing school ventilation as much as possible reduces the spread of COVID-19, but merely having staff open windows is not an adequate response, said Jeffrey Siegel, an expert on indoor air quality.

“I want people to understand that … we’re doing that because we have no better option,” said the professor at the University of Toronto’s department of Civil and Mineral Engineering and Dalla Lana School of Public Health. “If it’s the solution we have, we should use it. But I sure hope that we can do better for our schools than just saying, ‘Yeah, open the window.’ ”

While the larger respiratory droplets blamed for most coronavirus transmission typically fall to the ground quickly, the virus can also travel on clouds of warm, moist air indoors. In addition, the water contained in respiratory droplets evaporates rapidly, leaving microscopic particles called aerosols that can move for long distances on indoor air currents – similar to the way cigarette smoke wafts through a space.

Since schools reopened, provincial public-health officials have maintained that student and staff infections are a reflection of community spread and have not driven the second wave of the pandemic. However, as the weather has gotten colder, outbreaks tied to schools have climbed in some parts of the country.

What to do about potential airborne transmission of the novel coronavirus in often-crowded classrooms is a matter of intense debate among parents, teachers’ unions, governments and experts.

The results of The Globe’s informal survey showed that the majority of large school boards have increased the intake of fresh air in schools with central heating, ventilation and cooling (HVAC) systems and are opening windows in classrooms without mechanical ventilation. However, most are awaiting public-health guidance before taking further steps.

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Increasing ventilation is especially important in older schools that depend on air infiltration through open windows and doors rather than HVAC systems, which circulate a mixture of fresh and recirculated filtered air using fans and ducts.

Most major investments in air-quality improvements were concentrated in Ontario and English-language boards in Montreal.

Of the 26 school boards surveyed, eight have installed or ordered portable air purifiers for classrooms without central ventilation systems. Five are in the Toronto region, one in Ottawa and two in Montreal.

Justin, the caretaker at Saint-John Fisher Senior Elementary School, sprays a classroom where students were during the installation of HEPA filtered ventilation systems.

Andrej Ivanov/The Globe and Mail

Public boards in COVID-19 hot spots such as Saskatoon, Winnipeg and Calgary have no plans to buy air-filtration units, while all but two of the six surveyed in Quebec are waiting for instructions from the province. The Atlantic provinces, with their comparatively low case counts, had no major plans to tackle indoor air quality.

Most boards surveyed have asked school staff to open windows at least some of the time, whether they’ve purchased equipment for other ventilation improvements or not.

The Toronto District School Board (TDSB), the country’s largest, and most of Quebec’s school system have asked parents to dress their children more warmly in preparation for chilly classrooms.

“As we head into the colder months of the year, open windows will continue to be an important step to increase fresh air in classrooms and schools,” the TDSB said in a Nov. 26 letter to parents. “While heating systems will be turned up, we still expect that schools will be cooler than normal.”

The board has installed about 3,500 HEPA (high-efficiency particulate air) purifiers in all “occupied instructional spaces that do not have mechanical ventilation,” said spokesman Ryan Bird. The board spent about $3-million on 3,000 units and received a donation of 500 more from a company.

The TDSB says air-filtration units are not necessary in classrooms with mechanical ventilation, citing advice from Toronto Public Health.


Some boards go it alone

Montreal’s Lester B. Pearson school board was the first in Quebec to plunge ahead with new air filters. Last summer, Bruno Côté, the board’s engineer in charge of equipment and buildings, started reading a growing body of research suggesting aerosol particles play a role alongside larger droplets in spreading COVID-19. By August, he started working on a plan to install filtration systems in the board’s 420 classrooms that rely on natural ventilation for fresh air.

“We knew the windows would be fine for summer, but in winter, when we sometimes have Arctic temperatures, we didn’t think it would work,” Mr. Côté said.

A debate raged through the summer and fall in Quebec and across the country about whether air filtration should be installed. Officials often balked at cost and logistical hurdles: more than half of Quebec’s schools are considered to be in bad shape over all in the government’s own assessments. As school started, neither federal nor provincial health authorities had acknowledged aerosol transmission even existed.

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Montreal’s Lester B. Pearson school board was the first in Quebec to push ahead with new air filters.

Andrej Ivanov/The Globe and Mail

Mr. Côté drafted a plan adapted for classrooms and underpowered electrical systems. The units would have to be small and quiet and run off a standard 110-volt plug-in and use 175 watts and 2 amps, a bit more draw than a household fan, a bit less than a medium-sized modern television.

The board’s technical team started working on calculations and sketches, and hired an external engineering company to confirm their work. In early November, just after public-health officials in Ottawa and Quebec officially recognized aerosol transmission, the board ordered 420 wall-mounted units at $1,235 each, for a total cost of $518,700.

The installation is almost complete.

Money the board usually uses to replace desks and other equipment was used to buy the purifiers. “We were concerned in September and October because units were selling out,” said Carole Heffernan, assistant director-general of the board. “We made the decision quickly because we wanted them in by Christmas.”

The English Montreal School Board followed in the first week of December and ordered 800 units for $1.4-million, despite earlier saying that they were waiting for instructions from the province.

Of the boards The Globe surveyed, the Toronto Catholic District School Board was the first to hire outside experts to test air quality at “samples of schools with various types of ventilation systems and windows,” the board said in an e-mail. Measuring carbon-dioxide levels determines how much exhaled air from other people is lingering in an indoor space, which serves as a proxy for COVID-19 risk.

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The results from last month’s testing are not yet available, said the board, which has also purchased about 2,300 HEPA air cleaners.

Some parents and teachers, it turns out, are running their own air-quality tests.

A Grade 6 classroom at Hunter's Glen Junior Public School in Scarborough, Ont., on Sept. 14, 2020.

POOL/Reuters

When classes started in September, Toronto parent Alan Majer was nervous about the air quality in the TDSB classrooms of his 15-year-old daughter and 13-year-old son, so he tucked carbon-dioxide sensors in their backpacks. The meters recorded safe levels.

“Maybe it’s a little covert, but I’m so happy I did because I just feel so confident about my kids going to school,” said Mr. Majer, founder of a company that makes air-quality sensors. “Until then, I was quite worried.”

As the school year progressed, Mr. Majer began lending off-the-shelf CO2 meters to teachers. So far, he’s been contacted by more than 30, some of whom have said they’ve been denied approval to do testing by school administrators.

“To me, I guess I can’t conceive of people saying no. The idea that you can’t measure the safety of the air you breathe? It just doesn’t compute for me,” he said.

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Public-health advice lagging

While experts are relatively in agreement that aerosol spread is helping drive the pandemic, a lack of consensus from public-health officials on the value of portable air filtration has meant that school boards have not widely embraced such technology over opening windows, even in winter.

“The [school division] has reviewed air quality and options in recent months … as air purifiers circulate air and droplets in the air, we have not installed air purifiers in classrooms,” said Radean Carter, a spokesperson for the Winnipeg School Division.

Their schools will increase airflow from the outside, including opening windows while “keeping in mind external conditions such as extreme cold or extreme humid conditions impact on the quality of the inside air, and adjusting accordingly.”

The Quebec government, which directly controls French-language school boards while English boards have more autonomy, has spent the fall counting how many classrooms lack mechanical ventilation (1,870 out of 3,227). Once that study was done in the first week of December, the province ordered air-quality tests. A provincial public-health committee is studying air purifiers.

“The debate is not settled and experts are studying it,” Education Minister Jean-François Roberge said. “Some think purifiers could be useful, some think they could boost transmission. We are not going to invent scientific protocols on the back of a napkin.”

While no peer-reviewed research has proved portable air cleaners reduce the risk from COVID-19, studies have found they lower transmission of illnesses spread in similar ways, such as influenza and tuberculosis. Given that, Prof. Siegel, the U of T indoor air-quality expert, said it is logical to assume that properly sized, installed and maintained units would reduce coronavirus spread.

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Prof. Siegel urges work on multiple fronts to improve school ventilation and air filtration – including installing portable purifiers – even for classrooms that meet current standards. He added that relying on open windows creates uncontrolled air flow, uncomfortable temperatures and low humidity in winter, which increases the risk of COVID-19 transmission.

“Going into winter, ventilation is going to be a hard thing to do well and so it makes sense to supplement it with filtration, especially where it’s most needed, where we can’t do much with ventilation,” he said.

For the past few months, Toronto parent Sam Kaufman has been contacting TDSB officials and making presentations to trustees about ventilation but is frustrated with what he considers the board’s lack of transparency on whether it has developed classroom-specific plans.

“It’s the nitty gritty of what’s actually going on in each classroom,” he said. “They’ve had months to do this.”

Mr. Kaufman said he has noticed windows closed even on mild fall days at his seven-year-old son’s school.

“How many windows have to be open to ensure a reasonable ventilation rate on the full day? How’s the teacher supposed to guess?” said Mr. Kaufman, a data scientist. “This is going to vary from classroom to classroom but how’s the teacher supposed to know, if you haven’t done any assessment or developed any clear guidelines?”

Mr. Bird, the Toronto board spokesman, said the TDSB “takes its lead” from the Ministry of Education and Toronto Public Health and “has implemented their advice with regards to infection control and prevention.”

In addition, Mr. Kaufman is upset that the TDSB is not allowing parents to raise money to buy air purifiers for all classrooms. Mr. Bird said funding for filtration units in classrooms without mechanical ventilation has already been provided by the provincial government.

Harvey Bischof, president of the Ontario Secondary School Teachers’ Federation, faulted Doug Ford’s provincial government for not requiring an “objective yardstick” in the form of school ventilation standards, saying it was incumbent on the province to provide adequate funding.

Caitlin Clark, a spokeswoman for Education Minister Stephen Lecce, said the province is “proud to lead the nation in COVID-19 school reopening funding,” including announcing $50-million for ventilation in mid-August, followed by additional investments.

Two school boards, Newfoundland and Surrey, did not answer repeated requests about their air-quality plans.

Science reporter Ivan Semeniuk outlines how Canada benefited from researchers working in parallel and accelerated the approval process to have a safe COVID-19 vaccine ready so quickly.

Sign up for the Coronavirus Update newsletter to read the day’s essential coronavirus news, features and explainers written by Globe reporters and editors.

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