Here's how schools in Thunder Bay measure up to Ontario standards on HEPA air filters

Experts say high-efficiency air filters are a key tool to keep COVID-19 out of the classroom as schools reopen. CBC News examined Thunder Bay's Catholic and public schools and found they have different approaches, but still meet key provincial standards.  

HEPA filters, which stands for high-efficiency particulate air filters, can reduce the concentration of some viruses in the air by capturing small particles, such as the water droplets that can carry the coronavirus. Ontario's Education Ministry has put in place rules for having them in schools depending on each building's ventilation system.

Since Thunder Bay Catholic District School Board's classrooms have mechanical ventilation systems, they have deployed  52 units across it's schools, following the guidance from the ministry, said Paul Mingault, the manager of plant services with the Catholic board. 

Mignault said the board is expecting 20 more units, which will go into special education classrooms, when they arrive. 

"The air quality in the schools, I think, it's better than pretty much anywhere. I mean, we focused a lot on this," he said. 

"We're bringing in more fresh air now than we ever have," he said. "Now with the addition of these separate units, it just increases the air quality as well. So they're very safe. It's a very safe place to be for our students and staff."

LISTEN | Why is there a difference in the number of air filters at each Thunder Bay school? 

Initially the guidance from the ministry of education required all junior kindergarten (JK) and senior kindergarten (SK) classrooms to have the filtration units since masking was previously not required in those grades. Areas of schools without mechanical ventilation were also required to have the HEPA filters.

"Since COVID started, we've done a numerous amount of changes, our units start up and stop, you know, two hours prior to school, two hours after, we've done a lot of duct cleaning," said Mignault, adding the units are just one layer of protection for staff and students.

The Lakehead Public School Board, however, took a different approach and invested in hundreds of the HEPA filters.

"We are, I guess, over and above what most boards are doing. We currently have 374 dispersed throughout our system which is more than we were recommended to do," said Jim Desaulniers, manager of property services for Lakehead Public Schools.

The school board, which is the largest in the city, purchased the extra 130 filters with funding from the government to add more protection for people in the buildings. 

The public board is expecting 22 more filters from the province, which will be distributed "equitably and fairly" across the boards 27 sites, Desaulniers said. 

"A lot of it's at the discretion of the principal. With the attendance, which classrooms have, you know, a greater pupil count that would be a good candidate. If they have teachers that have any health issues, that would be another candidate," he said.

Desaulnier added that many other projects are in the works to better to protect classrooms among the board moving forward. He said full studies are being conducted at some sites to determine how the systems are working, while others are receiving new windows and outdoor classrooms.