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Calgary schools, businesses improve ventilation to stop COVID-19 spread


When COVID-19 restrictions lifted in Alberta, the owner of Kaffeeklatsch decided to find a way to improve ventilation.

“So people who are here are breathing the freshest air that they can, which minimizes the risk of contracting COVID,” said Jessica McCarrel, who runs the coffee shop by day and nightclub by night.

First, McCarrel installed a CO2 monitor, which can detect how much fresh air is in the space and signal when it might be a good time to open a door or window.

Health Canada’s recommended CO2 exposure limit is 1,000 parts per million. People who are exposed to CO2 levels between 800 and 1,000 can begin seeing respiratory symptoms like sore or dry throat, congestion, runny nose, sneezing or coughing in office or school settings.

McCarrel has taken it even further, putting out a call on social media, asking for help building a Corsi-Rosenthal box, which is a do-it-yourself air purifier.

“We wanted to keep our patrons as safe as possible. And this was like the best way that we could think of, and the cheapest, most affordable way that we can keep the air quality as safe as possible,” she told CTV News.

That’s when she connected with Amanda Hu, an advocate and parent with Fresh Air Schools Alberta.

The pair came up with a plan to improve air quality in the space for staff and customers, which involved using Corsi-Rosenthal boxes and HEPA filters.

“It actually takes out all of those particles, you know, dust, smoke and COVID, the viral aerosols, and traps them into filters and then pushes out clean air,” Hu said.

“It creates a safer more encouraging work environment and it’s something that consumers are increasingly looking for.”

The air purifiers were just installed over the last few months and McCarrel says feedback from staff and customers has been positive.

“A lot of people don’t even notice that it exists and it is keeping them safe regardless of whether they want it or not,” she said.


It’s not just businesses taking these extra measures.

Edelweiss Preparatory School also uses CO2 monitors and as a result, has increased the number of HEPA filter air purifiers in each classroom from one to three, and has made them available in other rooms in the building.

The school has also made changes so all windows in the classrooms can open and installed a retractable screen door in one of its rooms to bring in fresh air when the CO2 levels are elevated.

“We spent $10,000 to do this in our school and to us, it’s worth all of it because it’s helping to mitigate risk for our students, our parents and our staff,” said Margaret Reid, owner and director of the school.

Edelweiss Preparatory School began these measures last school year and said parents’ input has been helpful.

“We actually had some parents in the medical profession that had expertise and were able to guide us a little bit in getting the CO2 monitoring going,” Reid said.

“And all the parents are really appreciative of the fact that we do this here in the school for the benefit of everyone.”

The Calgary Board of Education (CBE) upgraded to MERV 13 filters in schools this spring and will keep them in place for the upcoming school year, changing them more frequently than previous filters.

It said all schools are mechanically ventilated and systems are set to maximize air exchange.

“The CBE takes the health and safety of our students and staff seriously,” it said in a statement.

“School boards across the province have not received direction from Alberta Education or Alberta Health regarding changes to ventilation requirements for the 2022-23 school year.”

Meanwhile, the Calgary Catholic School District (CCSD) said it is following recommendations for reducing airborne infectious aerosol exposure, such as using an improved microfilter fabric in its air systems, maximizing fresh outdoor air in its HVAC systems and increasing its air changes per hour. Top Stories

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