Experts in the ventilation field are disputing claims made by Education Minister Dominic Cardy about using HEPA filters in schools as a solution to the many poor and dated ventilation systems throughout the province.
In a Q&A with CBC New Brunswick, Cardy was asked about solutions to school ventilation issues.
He said the recommendation thus far was not to do little band-aid measures because those sometimes make things worse, adding, “in-class HEPA filters, for example, as much as they can absorb some COVID-19 into them, when they’re circulating air in the room, they can be moving COVID air around and actually infecting more people. So, that’s why we say for this year again, leave off with any discussions around fans and ventilation systems because the evidence just wasn’t there that they would work.”
But that isn’t exactly the science says engineer David Elfstrom.
“A HEPA (high-efficiency particulate) air filter does not ‘absorb COVID-19.’ It traps respiratory aerosols emitted when we cough, shout, talk, sing and even breathe,” Elfstrom said in an email.
“Ventilation with outdoor air and filtration are two ways to keep concentrations of aerosols from building up. Both methods rely on mixing the air, which requires air movement. Merely moving the air without exchanging it with outside air or filtering it, can create local pockets of higher concentrations of aerosols.”
Cardy also said the evidence that they would work “just wasn’t there.”
The experts weigh in
Elfstrom added Cardy’s comment directly contradicts statements made by the American Society of Heating, Refrigerating and Air-Conditioning Engineers — a professional organization that represents professional engineers who design heating, ventilation and air-conditioning systems.
Those statements include:
“Airborne transmission of SARS-CoV-2 is significant and should be controlled. Changes to building operations, including the operation of heating, ventilating, and air-conditioning systems, can reduce airborne exposures.”
“Ventilation and filtration provided by heating, ventilating, and air-conditioning systems can reduce the airborne concentration of SARS-CoV-2 and thus the risk of transmission through the air. Unconditioned spaces can cause thermal stress to people that may be directly life-threatening and that may also lower resistance to infection. In general, disabling of heating, ventilating, and air-conditioning systems is not a recommended measure to reduce the transmission of the virus.”
Elfstrom said Ontario was given a report by their Science Table that made them require the use of HEPA filters in schools through a memo.
“The memo outlines the requirement by schools to place portable HEPA units in certain school locations, such as all kindergarten classrooms, and in classrooms without mechanical ventilation,” he said in an email.
Engineer Aaron Smith also can’t make sense of Cardy’s comments.
“I’m not aware of any issues of moving COVID around. In fact, the filters themselves should be filtering COVID out of the air and filtering clean air into the room,” he said in an interview Thursday.
He said HEPA filters come with the recommendation from the highest working professional group governing engineers and ventilation systems in the country.
The American Society of Heating, Refrigerating and Air-Conditioning Engineers recommends the use of HEPA filters for exactly the circumstances New Brunswick schools find themselves in.
Global News requested a comment from the Education Minister on Thursday but did not receive a response by publication time.View link »