Experts examine U of T’s filtration system, COVID-19 safety – The Varsity

As students return to campus for the fall semester, the university reviewed University of Toronto ventilation and filtration mechanisms with Colin Furness – assistant professor in the Institute of Health Policy, Management, and Evaluation – and Jeff Siegel – professor in the Department of Civil and Mineral Engineering. Siegel and Furness discussed the ability of effective filtration to reduce the risk of transmission of airborne pathogens and elaborated on their concerns regarding deficiencies in current U of T filtration systems.

The University of Toronto Students’ Union had previously criticized delays in providing information about the university’s ventilation and filtration procedures, and also expressed concerns about the procedures themselves. Following these criticisms, the university administration assured the U of T community of the strength and effectiveness of its ventilation and filtration plan.

Basics of ventilation and filtration

Furness highlighted the vital role air quality plays in efforts to combat the ongoing pandemic. “We need vaccination, we need people to behave responsibly, [and] we need a functioning health system,” he said. “But really, in order to be able to get back to normal, we need to manage our air like we managed our water, which is to make sure it’s clean before we drink it.”

Two processes underlie clean air: ventilation, which involves replacing indoor air with fresh air from outside, and filtration, which involves cleaning recirculated air.

The importance of ventilation and filtration stems from the airborne nature of SARS-CoV-2 – the specific type of coronavirus responsible for the COVID-19 pandemic. “[SARS-CoV-2] is in the air, and that’s something the provincial governments haven’t really recognized,” Furness said.

Although the World Health Organization recognized airborne transmission of COVID-19 in December 2021, the Province of Ontario has not imposed any additional measures to improve air quality.

Furness believes this situation represents a missed opportunity. “If you have maximum ventilation… the air looks a lot like outside air. What we know about the study of viruses in general and COVID in particular [is that the] outside is much safer than inside,” Furness continued.

Siegel pointed out that adequate ventilation and filtration have benefits beyond simply reducing COVID-19 transmission. “We have a variety of other respiratory illnesses that are common every year,” he said. These diseases not only pose a danger to people’s health, especially for the most vulnerable populations, but also interrupt learning. “I would say any investments we make in things like ventilation will pay off for those things as well,” Siegel said.

A 2013 study by the U.S. National Library of Medicine found that heating, ventilation, and air conditioning (HVAC) filtration systems help reduce the risks of certain airborne pathogens, including rhinovirus , which is implicated in the common cold; flu; and coronavirus.

Status of campus buildings

In April 2021, the U of T’s Utilities and Operations and Environmental Health and Safety jointly conducted an assessment of the university’s HVAC systems. Following this assessment, they created a list of recommendations to guide the university’s ventilation and filtration policy, which the university has implemented.

The university’s HVAC procedures now include turning on ventilation systems two hours before a building opens and turning off controls for ventilation systems that reduce airflow.

The university has also affixed Minimum Efficiency Reporting Value-13 (MERV) rated filters – filters capable of capturing smaller particles that can pass through the air. According to Furness, “MERV 13 is considered adequate for infection control purposes, and the gold standard is MERV 16.”

Of the 107 buildings on St. George campus not operated by federated colleges, 23 do not contain central mechanical ventilation, including the University of Toronto Graduate Students’ Union, Sir Daniel Wilson Residence and Whitney Hall. However, many of the busiest buildings on campus—including Hart House, Robarts Library, and Sidney Smith Hall—contain HVAC systems with filters rated MERV 13 or higher. At the Mississauga and Scarborough campuses, all buildings are equipped with filters rated MERV 13 or higher.

The university is also committed to ensuring that every classroom receives six equivalent air changes per hour (ACH) when in use, the same standard applied to healthcare facilities. Also, the university measures ACH in every classroom in the university.

For classrooms that do not meet the six ACH threshold, the university has restricted the use of the room, modified existing HVAC equipment to allow the room to meet the threshold, or installed air filtration units. localized air to supplement airflow.


Asked about potential shortcomings in the University of Toronto’s CVC strategy, Siegel cited the university’s broader COVID-19 policies. Siegel explained that epidemiologists often visualize disease prevention using a Swiss cheese model in which each protective layer has holes, but, by layering the protective measures, it is possible to prevent the spread. pathogens causing the disease. “If you think of the ventilation as one layer, there are a bunch of holes,” Siegel said. Without a mask or a vaccination mandate, he added, “we rely on just one layer, and we’re not doing everything we can to make sure that layer is as protective as possible.” U of T vaccine and mask mandates have been suspended since July 1.

Furness believes there are many holes in the university’s HVAC systems. “Any building that was built before COVID will be built to some sort of normal standard,” Furness said. “Old buildings like Hart House, Trinity College or Victoria College are powered by the university’s steam heating system. There is a whole built-in network of steam pipes providing heat, so there is no systematic forced air.

Despite setting strict standards for classrooms, the U of T has not set similar standards for other parts of the buildings, such as offices, entrances, and common areas. The university’s rationale is that these areas are not as likely to have the same risk of transmission as crowded classrooms.

However, according to Furness, this oversight presents a problem. Describing buildings as “dynamic systems” where air constantly circulates between classrooms and the environment, he explained that students spend a lot of time in spaces other than classrooms. “We haven’t touched on ventilation in a lot of [non-classroom] spaces,” he said.

According to Siegel, even the ventilation measures the university has implemented in classrooms are not necessarily adequate. He explained that the air filters that are used in centralized filtration at UTSG have a very high initial filtration rate, but often degrade quickly.

Siegel added that portable air filtration systems, such as those used in classrooms, also pose a number of challenges. He noted that such filters provide localized coverage, but they don’t necessarily protect the entire space. Filter noise, Siegel continued, can also cause some people to turn off or turn off devices.

Although the university claims to be on top of maintaining filtration units, Siegel warns that there may simply be too many units for the administration to maintain and oversee. “I guess we’ll see [unit] removal rates that are two or three times lower than calculations suggest in many places,” Siegel said.

U of T Response

In a statement to the universitya U of T spokesperson said its ventilation and filtration measures “impact all areas of the buildings, including hallways, meeting rooms and common areas” and that “all systems are regularly inspected and maintained in accordance with system specifications and best practices”.

According to the U of T spokesperson, additional air purifiers are being used in classrooms that do not meet the six ACH threshold. The spokesperson added that the air purifiers were last inspected by a third-party expert in August.

The spokesperson explained that upgrades to a building’s ventilation system are partly determined by the condition of the building in question: “For example, in heritage buildings, renovations and system changes may not not be allowed.

There are 86 heritage buildings on U of T campuses, only six of which are not located on the UTSG campus. The university works with the City of Toronto to ensure the preservation of these buildings and must consider various guidelines when implementing any changes or modifications to these buildings.

The spokesperson concluded that, although the university suspended its mask mandatestudents are encouraged to wear masks in crowded spaces and to respect everyone’s decision to do so.

With files by Syeda Maheen Zulfiqar.

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