CLEARING THE AIR
Schools race to improve ventilation as a way to help control potential COVID-19 pathogens
Sam Caskey installs an upgraded filter as Surrey schools work to increase the flow of fresh air into buildings by adjusting heating, ventilation and air conditioning equipment. For decades, schools were sealed up tight in a bid to be energy efficient, but now the race is on to improve ventilation and neutralize COVID-19 pathogens.
The best indoor air in the region may be in the four classrooms that make up the Glarea Elevated Learning independent school in Surrey.
Construction was just getting underway in March when B.C. went into a COVID-19 lockdown and the private school's trio of founders quickly pivoted to update their plans for the ventilation system.
The timing could not have been better.
“We had just demolished and were putting up the walls,” recalled co-founder Nadia Irshad. “We were hoping to run some summer camps, but the pandemic changed those plans.”
The hiatus allowed them the time to install some serious tech in the school's new space, overlooking the rinks at Excellent Ice formerly occupied by a cafeteria and bar.
The $500,000 ventilation system includes real-time monitoring of air flow and oxygen, filters and ultraviolet light disinfection to kill potential pathogens in the air.
“It's really robust and there are air-flow vents everywhere,” she said. “When there was so much wildfire smoke in September, you couldn't even smell it inside.”
The build also incorporates motion-activated sinks, body temperature monitoring and hand-sanitizing stations.
“We didn't know at the time how long the pandemic would last, but I guess it could be with us for some time,” said Irshad. “It was just good timing, but we are feeling really good about the decisions we made then.”
To date, there have been no cases of COVID-19 reported among students and staff. The school has 20 pupils from kindergarten through Grade 5.
“We keep our learning cohort to 30 people, rather than the 60 in the instructions from the ministry,” she said. “We have a lot of space and we are teaching the kids to distance from each other.
“We feel really safe,” she added. “What my older son is experiencing in the public school system is very different.”
COLD CLASSROOMS
The provincial government maintains that “there is no evidence that a building's ventilation system, in good operating condition, is contributing to the spread of the virus.”
Nonetheless, public school teachers have been instructed to move their students outdoors when possible and open classroom windows “if weather permits.”
Students are wearing sweaters and coats in classrooms to defend against the cold when the windows are open, say parents and teachers responding to an inquiry from Postmedia.
An Abbotsford Grade 1 teacher confirmed she is keeping her classroom's “two small windows” open all the time and the door ajar.
“Kids have complained about being cold, but I have asked parents to send an extra hoodie or warm sweater for their child to keep at school to put on when it is colder,” she said. “Better cold than COVID, I say.”
While children are holding up well to the cold, windy weather and storms can be a distraction, parents say. Not every classroom has windows that open. In some cases, non-opening windows that were recently installed are being removed.
“We are still waiting for the windows to be replaced so that they can open,” said Sunshine Coast mother Karla Shields. “Three years ago, they replaced the windows so that they wouldn't open.” She said new windows are apparently on back order.
While there have been cases of COVID-19 reported between students and staff in B.C.'S 1,900-plus public and independent schools, “transmission in schools have been very low,” said the provincial health officer, Dr. Bonnie Henry. Public health officials say that the vast majority of sick students acquired COVID-19 in a setting other than the school.
B.C.'S health regions have reported about 150 exposures, meaning a child with a lab-confirmed case of COVID-19 is known to have attended class during their infectious period.
Just two schools are currently reporting a cluster of two or more cases in which transmission of the virus at school may be involved.
Nonetheless, Henry last week announced that a team of provincial health officers was being formed to “identify and manage school exposures and outbreaks as quickly as possible.”
UPDATES AND UPGRADES
School districts were instructed to upgrade the filters in their recirculated air systems to a “minimum MERV 13 filter or higher,” in the provincial COVID-19 Health & Safety Guidelines for K-12 settings.
Fresh air intake is to be increased, where appropriate systems exist.
The Surrey school district has increased the amount of fresh air being pulled into all its buildings with a variety of adjustments to heating, ventilation and air conditioning — or HVAC — equipment, a spokesperson said.
The minimum amount of outside air drawn in has been increased from 10 per cent to 25 per cent, the CO2 set point has been lowered, which increases the rate at which the system replaces indoor air, and systems are set to run as though the building is occupied for four additional hours each day.
Filters and HVAC monitoring systems are being upgraded, though some systems are too old to use the MERV 13 filters mandated by the province. The cost of the work so far is about $430,000.
In Vancouver, teachers continue to conduct activities outdoors and keep classroom windows open when possible and HVAC systems have been adjusted to increase air intake, a spokesperson said.
Some of the district's first instalment of the Federal Safe Return to Class Fund — about $9 million — will be applied to “HVAC and ventilation improvements.”
The provincial government provided $45 million to school districts in July, while the federal government committed $242 million to be spent in two phases in B.C., according to the Ministry of Education. To date, 48 of B.C.'S 60 school districts have upgraded systems to increase air exchange and 26 districts have upgraded filters used in their buildings.
THE HVAC CONUNDRUM
Modern cities generally have a large stock of buildings that rely on HVAC systems that create built-in tension between energy efficiency and personal control.
While such systems control temperature, humidity and air flow, they can be defeated by open windows. Openable windows are also harder to seal, which leads many builders to opt for fixed glazing — windows that can't open.
That leaves indoor workers in a tough spot, relying on HVAC systems to protect them from a virus.
In commercial buildings, such systems are meant to draw in outside air and either heat or cool the environment, said Eric Douglas, an architect and PHD candidate at UBC'S school of community and regional planning.
“It's not designed to isolate a person infected with a virus from a person who is not infected,” he said. “You can use filters and UV to zap infectious diseases, but it's not designed to do that within a single space.”
The government's instructions to teachers to open all their windows is an admission that HVAC systems are not adequate for the task that they are being asked to do, he said.
“We've got to keep kids in school for a whole variety of reasons, and opening the windows probably seemed like a good idea in August, but it's going to get cold,” he said.
With modern HVAC, it is possible to override the system to increase the rate of “air changes per hour,” but that's not really how the systems were envisioned to work.
For decades, buildings have been designed to be as energy efficient as possible, sealing them up and running heaters and air conditioning “just enough to maintain air quality and comfort.”
“Then the pandemic hits and it's `Oh my God, we have to run the heck out of them,' ” said Douglas.
Douglas said that the only way to know whether a building's HVAC is working well enough to protect human health is to audit every building and address its shortcomings.
THE VIRAL MATH
“We know that air -low rate is important and we can put that ventilation rate into equations that tell us the probability of a disease being transmitted,” said Karen Bartlett, professor in the school of population and public health at UBC. She said that can be done for tuberculosis, measles and the virus coronavirus.
What remains unclear is how long the virus carried in exhaled respiratory droplets retains its “infectivity” as the droplets dry out and fall out of the air, she said.
Early in the pandemic, a transmission at a restaurant in China sparked concern about the role of air conditioning in transmission of COVID-19. In that case, strong directional air flow is believed to have carried droplets containing the virus from an infected individual at one table to people at an adjacent table.
“Things got a little muddled and people were attributing ventilation as being the cause of the transmission,” said Bartlett. “It is not the problem. A functioning HVAC system will dilute pollutants in the indoor environment and exhaust them.”
And there is nothing wrong with opening the windows as part of a strategy to reduce transmission.
“Replacing indoor air with outdoor air in a classroom, for instance, is desirable,” she said.
But ventilation is only part of the solution.
“If you are in close contact with an individual who is infected, ventilation isn't going to do anything,” said Michael Brauer, a professor at UBC'S school of population and public health. “Air movement would have to be so high that it would be windy inside, mimicking the outdoor environment.”
Instead, people should rely on maintaining physical distancing, wearing masks and washing hands, “all the things that we've been saying all along.”
That's not say there is no value in adding fresh air to indoor spaces.
“Opening the windows is simple, we know it's effective, and we aren't in a climate where it's impossible to do,” he said.
Fully exchanging indoor air that may contain droplets or aerosols capable of transporting the virus with fresh air that is free of the virus has demonstrable value.
It acts as a kind of reset for the time you can safely spend in a place where someone may be infected, he said.
We know that air-flow rate is important and we can put that ventilation rate into equations that tell us the probability of a disease being transmitted.