HEPA filters can only help combat COVID-19 in classrooms, says expert
Education minister has suggested adding high-efficiency particulate filters could make transmission worse
Linsey Marr, of Virginia Tech, says "there's no question" HEPA, or high-efficiency particulate, filters can improve air quality.
And she doesn't see how they could be harmful — "unless people take apart the HEPA air cleaner and grab the filter and start, you know, rubbing it on their face."
Sixty schools in New Brunswick have no integrated mechanical ventilation systems, as of September. Unlike the 234 schools in the province that do have integrated ventilation systems, these schools must rely instead on opening doors and windows to circulate air.
While other provinces, such as Ontario, spent millions on HEPA filters for schools before classes started last fall, New Brunswick plans to hire an outside expert to review the "competing science" surrounding the issue and provide recommendations, Cardy has said.
HEPA-filtered
air purifiers like this one, in a Toronto public school, can reduce the
concentration of some viruses in the air by capturing small particles,
such as the water droplets that can carry the coronavirus, says Marr. (Evan Mitsui/CBC)
Earlier this week, before students returned to virtual learning following the Christmas holidays instead of in-person classes because of an ongoing surge of COVID cases and hospitalizations, CBC News asked Cardy why HEPA filters weren't used in schools at the start of the pandemic.
"When I went and asked experts in my department and folks across government about HEPA filters, they said, actually it's not quite as clear cut as that. There's actually a lot of information that it might actually make things worse," he said.
"So no problem at all, admitting when we're off-base on something. But the last thing I want to do is add to the list of things that we're off-base on by starting off, by saying that this is definitely going to be a sure fix to a problem when we don't yet have that evidence."
Marr, who has been a leading voice on the airborne transmission of COVID-19 since the beginning of the pandemic, contends Cardy spoke to the "wrong experts, or they haven't caught up on the more recent information."
Earlier in the pandemic, there was much debate among virologists about how COVID-19 is spread. Many believed the primary mode of transmission was through large droplets.
But Marr says the highly transmissible Omicron variant has made it clear that COVID-19 is an airborne virus and we must act accordingly to stop it from spreading.
Sixty of New Brunswick's 294 schools do not have adequate ventilation systems, as of September. (Ivanoh Demers/Radio-Canada)
"We know from basic physics … if you have a filtration system in a smoky room, that's going to bring down the amount of smoke particles in the room," she said.
There have also been some in-hospital studies that are not yet peer-reviewed, which found less bacteria and viruses, including COVID-19, in the air, when HEPA filters were turned on.
"So, you know, between basic physics and these empirical, observational studies, it's very clear that HEPA filters can reduce the amount of virus in the air," said Marr.
The Public Health Agency of Canada says the effectiveness of HEPA filters in reducing the transmission of the SARS-CoV-2 virus "hasn't yet been demonstrated."
But HEPA filters can be used "as an additional protection in situations where enhancing natural or mechanical ventilation is not possible," it advises.
"When properly used, portable air filtration devices with high-efficiency particulate air (HEPA) filters have been shown to reduce the concentration of some viruses from the air."
On Dec. 24, the federal agency released guidance on choosing a portable air purifier.
It comes on the heels of a video offering COVID-19 guidance on ways people can improve ventilation and air filtration in their home.
"Ventilation is a key way to help prevent the spread of COVID-19," according to the description.
It replaces stale indoor air with fresh outdoor air.
"This helps to reduce the levels of infectious particles in the air," the video states.
People can open windows and doors to create a cross-breeze of fresh air.
They can also use air filters with their heating, ventilation, and air conditioning (HVAC) system or portable air purifiers with a HEPA filter, it advises.
With files from Information Morning Fredericton
And politicians don't work because they don't want to. Somehow your ten year old can figure out how to do online learning, but attending meetings remotely is impossible for an MLA.
His errors appear to be coming more frequently now.
— Simone Weil
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When they cancelled hockey and everybody yawned, i knew it was over. Maybe they can find an expert to explain how we are supposed to undergo the regular respiratory purge required by people who live where there is fall and winter. These players have been living close to an open fire since, well, they figured out how to do it, and with all the toxic smoke and wood and dirt particles and animal cooties and decomposing plant material and allergens from all that vegetation not to mention whatever industrial particles were launched into the air nearby, well, if they had not been somehow partnered up with "respiratory purge viri", players would have poison coated lungs until they died before reproducing. I guess this is old fashioned so, yeah, by all means hand the administration of your immune system over to the state. They seem to know what they are doing. Right?
David Amos
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Reply to @Allan J Whitney: Well put
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I lived up at the top of Forest Hills in Saint John years ago and I can remember the CO alarm going off a few times throughout the year.. I investigated about putting in HEPA filters in my home to keep the smell out and I was told by several different stores the HEPA filter would do no good against the SO..... I got the he!! out of there in a year.. Moral of the story A HEPA FILTER WILL NEVER STOP THE SARS COV 2 VIRUS.....
Clive Gibbons
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Reply to @Jack Smith: A Co molecule is orders of magnitude smaller than Covid virus. Same way a window screen doesn't stop cold air, but it does a great job with mosquitoes.
Graham McCormack
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Reply to @Jack Smith: And your educational background is what again? Checking with store owners?
David Amos
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Reply to @Graham McCormack: Good question
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