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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.
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.
Open this photo in gallery
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.
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“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.
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发表于 2021-1-7 17:58:11
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