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Millions of dollars are being spent upgrading schools across the province, with the promise of better quality air for students and staff returning to classrooms next month amid a fourth wave of COVID.
In Hamilton, boards are outfitting schools with portable air purifiers, new ventilation systems, upgraded HVAC filters and new windows as part of a provincewide push to make schools safer for students.
Types of systems used vary among Hamilton schools. Tier 1 schools have supply, return and exhaust into and out of the building, while Tier 2 schools have supply and exhaust. These buildings are considered to be mechanically ventilated.
When you have a mechanical ventilation system ... you have air being taken out of the building and being exhausted into the ambient, and you have fresh air being brought in," said Serhiy Yarusevych, professor of mechanical and mechatronics engineering at the University of Waterloo. This air exchange is happening in ventilated environments."
Yarusevych recently led a study focusing on droplets produced by humans through coughing, sneezing, talking and breathing, which vary in size. Larger droplets, he said, are caught quite effectively by any type of mask." But smaller droplets - approximately the size of a hundredth of a human hair in diameter - are following the air quite freely."
They stay in the air for a long period of time, they can accumulate in indoor spaces and they can transmit the virus," he said.
The study found that common masks, such as cloth and blue surgical, catch about 10 per cent of these tiny exhaled droplets.
Combined usage of masks and adequate ventilation would be the best mitigation strategy for reducing the risk of transmission," he said.
Schools without mechanical ventilation - Tier 3 - use exhaust fans, which draw air out of a building, but don't have air intake that pushes outdoor air into a space.
About 20 per cent of Hamilton-Wentworth District School Board (HWDSB) buildings - A.M. Cunningham, Ancaster High, Bennetto, Buchanan Park, Frank Panabaker (north campus), Franklin Road, George L. Armstrong, Highview, Holbrook, Huntington Park, Mary Hopkins, Michaelle Jean, Norwood Park, Richard Beasley, Rousseau, Tapleytown, Westmount and Westwood - fall under this category.
These schools are typically heated with radiators and have exhaust units for moving air," said spokesperson Shawn McKillop in an email to The Spectator.
At the Catholic board, about seven per cent of schools - Blessed Sacrament, Our Lady of Lourdes, St. Eugene and St. Patrick - are not mechanically ventilated.
Hamilton-Wentworth Catholic District School Board (HWCDSB) chair Pat Daly said Tier 3 schools tend to be older buildings. Our Lady of Lourdes and St. Eugene, for example, were built in the 1950s.
Yarusevych said it's important to have fresh air going in, not just recirculating air within the room."
Alternatively, one can use filtration such as HEPA filtration to catch and remove these aerosolized particles," he said, adding that open windows will also help, provided there is cross ventilation and the weather is warm enough.
Schools identified as Tier 3 buildings will have portable HEPA (high-efficiency particulate air) filters - mechanical air purifiers that can catch up to 99.9 per cent of airborne particles of a certain size, when used correctly - in all classrooms and learning spaces, as required by the Ministry of Education.
HEPA filters will also be placed in all kindergarten classrooms at Hamilton schools, as well as special education classrooms in the HWDSB.
Another factor in optimizing air quality is the type of filter used in heating, ventilation and air conditioning (HVAC) systems.
In its guidance, the Ministry of Education asked boards to use the highest-grade filters possible, which refers to the minimum efficiency reporting values (MERV) - a rating of filter used in supply-and-return air systems - in school buildings.
Daly said HVAC filters in every single one" of the board's schools have been upgraded to MERV-13, which can catch between 50 and 90 per cent of particles, depending on size.
That happened throughout last year," he said.
A spokesperson for the public board said some schools will have this rating of filter, and others will not.
Not all systems can accommodate MERV-13, so we have increased the level of MERV where we can," McKillop said.
The HWDSB plans to do daily air flushes" from 6 a.m., meaning systems will be turned on about two hours before students arrive at school.
When mechanical systems operate in occupied' mode they provide ventilation to the building," McKillop said. While students are in the building the system will continue to operate in occupied' mode."
At the public board, five projects - Ancaster Meadows, Gatestone, Lawfield, Ray Lewis and Sir William Osler - have been completed, and another nine - CB Stirling, Gordon Price, James Macdonald, Memorial City, Millgrove, Norwood Park, RA Riddell, Sir Wilfrid Laurier and Westview - will be completed for Sept. 7.
Many more will be completed during the fall, in time for the December deadline.
Classroom ventilation units are being installed class by class and there will be a need to relocate when units are installed. Time of the relocation will vary school by school," McKillop said.
Daly said many" Catholic board projects are already complete, and the rest will be completed in the coming months.
It is unclear how many schools are not on the list for upgrades by the end of 2021.
Ventilation need to know
Ventilation grade
Schools have been rated based on type of ventilation system. Tier 1 schools have systems with supply, return and exhaust into buildings; Tier 2 schools have systems with supply and exhaust; Tier 3 schools have systems with exhaust only. Tier 3 schools are considered to be without or with partial mechanical ventilation, and will be supplemented with portable air filters.
MERV-13
A high-grade filter used in supply-and-return air systems that removes between 50 and 90 per cent of particles - virus, bacteria and allergens, such as dust and pet dander - depending on size. MERV filters above 13 are generally considered medical-grade.
HEPA filter
A high-efficiency particulate air (HEPA) filter is a pleated, often portable, mechanical air filter that can catch up to 99.9 per cent of airborne particles when used correctly.
Kate McCullough is a Hamilton-based reporter covering education at The Spectator. Reach her via email: kmccullough@thespec.com