Engineers urge Ontario government to update ventilation guidelines to stop the spread of COVID-19 in schools

On August 3, 2021, the Ontario Government unveiled its 2021-22 Guide to Reopening Schools followed by an updated ventilation best practice guideline for school boards.

The reopening plan outlines how students will attend in-person learning daily for the full school day (five instructional hours) in elementary and secondary schools across the province. It provides direction in terms of personal protective equipment (PPE), use of shared spaces and social distancing.

Since the pandemic began, engineers and other experts have been calling for the government to release a comprehensive back to school plan that addresses the airborne transmission of COVID-19, particularly in indoor settings such as schools.

OSPE’s letters to government sent throughout the year outline engineering knowledge on the need to address proper indoor ventilation and air filtration.

mark frayne
OSPE President & Chair, Mark Frayne, P.Eng.

“Engineers know if we are going to combat the Delta and future variants and a potential fourth wave, the need for proper ventilation and filtration of indoor air is paramount,” said Mark Frayne, P.Eng., President of OSPE. “OSPE is calling on the Ontario government to consult with engineers, scientists, HVAC specialists and other experts immediately to adequately address this issue before more outbreaks occur.”

Although OSPE is pleased to see the release of this ventilation best practice guideline, we believe that much more should be done to ensure the safety of schools.

The Ministry of Education should strive to meet the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Building Readiness Guide, which includes checklists to ensure the safe re-opening of schools. ASHRAE has also released extensive resources detailing how to conduct overall improvements to HVAC systems to properly mitigate virus transmission, that should also be followed in Ontario. More specifically, the province should strongly “consider consulting with a local professional engineer to determine the appropriate minimum RH levels based on local climate conditions, type of construction and age of the building under consideration.”

It is also essential that our province is making informed policy decisions based on the most current and reliable data. Although the Public Health Ontario document is comprehensive, it is dated March 9, 2021. Many of the resources and documents referenced since March 2021 have been updated to include new information, additional practices and procedures that reflect the most current understanding of how to control COVID-19 transmission, including the current and future variants of concern. Therefore, the government’s document should be reviewed and revised to include updated knowledge to ensure it stays current with best practices.

When it comes to best practices, engineering expertise suggests that the following additions should be made to the guideline on page 7:

Disable Demand-Controlled Ventilation (DCV) systems using Carbon Dioxide (CO2) sensors where feasible: 

  • Either disable control sequence or adjust setpoints to be at or near ambient outdoor CO2 levels (typically between 400 and 500 ppm).
  • Trend and monitor levels continuously if controls system is capable of doing so (use portable data loggers and handheld instruments and document readings where needed to demonstrate compliance with District or Campus requirements).
  • Consider adjusting to maximize outdoor air or disabling operation of DCV if it will not adversely impact operation of overall system (Temporary recommendation while operating under infectious disease crisis).
  • Systems incorporating diversity into sizing may require DCV to maintain ventilation to occupied spaces – consideration should be given to system capabilities and outdoor air flow rates should be maximized. 

Regarding the use of additional in-class equipment to increase ventilation and filtration rates, OSPE recommends that any equipment introduced in an indoor setting should have a noise rating of 60 dB(A) or less, to ensure that the equipment is not too loud and thus creates a noise-related hazard.

It is also extremely important that school boards develop lists of qualified professionals (including professional engineers) that can be brought in to review and make recommendations in higher risk settings where the wearing of face masks and other controls are not feasible. (i.e. music classes, lunch rooms, gymnasiums, etc.)

OSPE strongly believes that the incorporation of these changes to the ventilation best practice guideline would ensure that schools and communities are safer. As always, engineers at OSPE are ready and willing to meet with the government to discuss these recommendations further to ensure all young people in this province are protected as we continue to re-open the economy.

In The Media

OSPE’s letters to government have drawn recent attention from the media, where CEO, Sandro Perruzza, was able to reiterate the importance of involving engineers and other design professionals when assessing the airborne transmission of COVID-19 in schools. 

HEPA Filters in Schools
CTV News – August 5, 2021

Provincial funding to improve public school ventilation systems
CBC News – August 4, 2021

Ventilation and Ontario’s Back to School Plan
CP24 – July 31, 2021


Listen to Episode 1 of OSPE’s podcast Engineering the Future to hear from air quality expert and engineer Brian Fleck, P.Eng., on indoor air quality and the transmission of COVID-19

“This is bigger than COVID-19 – Indoor Air Quality (IAQ) affects how many sick days we take off of work, how happy we are, and how long we live,” said Brian Fleck, professional engineer and professor at the University of Alberta who, along with a team of medical scientists and engineers, is studying ventilation and how it impacts the transmission of the virus. “We have the opportunity now to make the air in the buildings where we live and work cleaner than the air outside. We just have to make that investment; the costs are small compared to the benefits we will reap in finance, health and wellness.”

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