Is there a risk of COVID-19 infection through building ventilation?

Q: I live in an old, small apartment, but I don’t know how strong the ventilation is. What is the risk of COVID-19 transmission between apartments?

The Public Health Agency of Canada has not yet updated official information on aerial transmission as a possible COVID-19 epidemic.

However, the international scientific community acknowledges that it is a real risk, if at all.

Both World Health Organization And that Centers for Disease Control and Prevention The US (CDC) has added aerial propagation to the COVID-19 guidelines.

Recently, the CDC said There is new evidence The virus can spread more than 6 feet in a closed space without adequate ventilation. “Sometimes the infected person was breathing hard, for example while singing or exercising,” Guidance explains.

However, according to CDC data, the virus is more common to spread through closer contact than aerial infection.

Meanwhile, Ontario’s official guidance on COVID-19 and heating, ventilation, and air conditioning (HVAC) systems. state “Overall scientific evidence does not currently indicate that COVID-19 infection occurs through the HVAC system … Air viability or airborne infection demonstrating airborne virus circulating in the HVAC system. Not”.

Alberta Public Health Authority It pointed out There is epidemiological evidence that the HVAC system may have contributed to the COVID-19 epidemic in restaurants, call centers and planes, but in these cases the epidemic due to close contact could not be ruled out.

As new scientific data became available through the pandemic, public health advice evolved and even reversed, as in the case of face masks. It is not uncommon for different jurisdictions to issue different advice.

One constant rule was to stay at home and limit contact with others. But is that the case for those who live in poorly ventilated apartments or condominiums?

Simple answer: Depending on the situation, the risk is still relatively low.

Jeffrey Siegel, a professor of civil engineering at the University of Toronto who specializes in ventilation and indoor air quality, was more concerned about infection in a single building in the early days of the pandemic, but that concern diminished over time. It states. Scientists have learned that distance plays a major role in the transmission of the virus.

“If someone is in a different apartment than you, there is certainly a risk, but I put it at a fairly small risk,” he says.

But he points out that it can still happen, Amoy Gardens Apartment in Hong Kong During the 2003 SARS epidemic.

In that case, the virus spread to more than 200 people in the building. However, Siegel states that very specific situations, such as wind blowing, ventilation, plumbing, and building design, have led to widespread transmission in that case.

“I’m more worried about corridor contacts, laundry room, and elevator contacts. It doesn’t take long, so the risk is low, but it’s still risky,” he says. “When you enter the apartment, you have the advantage of distance.”

When it comes to ventilation, Siegel states that there really isn’t a type of ventilation that is at higher risk than other ventilations. Risks are building-specific.

He gives an example of corridor ventilation, which is common in old and even some new buildings in Toronto. Fresh air is brought into the corridors, which eventually flows into each apartment.

“Imagine a scenario where someone is in an infected corridor. It’s dangerous if they’re spending a lot of time there and the air comes from them to you and your apartment,” he says.

Susy Hota, medical director of infection prevention and management at the University Health Network, states that another factor in ventilation is the frequency of air exchange. That is, how often the air in a particular space is replaced with fresh air.

“If a person with COVID has a small aerosol that is released into the air and coughs, it may be okay if the air is exchanged and there is no opportunity to come into contact with the aerosol,” she says. To tell.

“Most of the contact with aerosols is wiped out, and with just a few floating, it may not reach the level of infection that actually causes illness,” she continues.

Mr. Yasuda says that the direction of air flow is also an important factor. In many buildings, she says, air is pushed into the corridors and fresh air circulates in the unit.

According to Siegel, anyone concerned about building ventilation can take steps to make the air flow in the unit more stable.

He recommends finding a good HEPA filter that represents highly efficient particulate air and can (in theory) remove 99.7 percent of dust, bacteria and other suspended particles.

Another option is a window box fan. This helps push the air circulating in the apartment out of the window (except for noise complaints).

“The more you can deflate with either the fan or the window, the better you feel,” he says. “We call it flashout, and it’s a good habit to get used to regardless.”

Mr. Yasuda points out that windows are also a key to ventilation, and that it is the best option for those who do not know the ventilation status of the building.

“If the weather is nice, keep the windows open and make sure the room or apartment has fresh air,” she says.

Overall, Siegel emphasizes that your apartment or condo is a safe place.

“I want people to know that your home is still a sanctuary,” he says. “Even if your room is well connected to other units, it’s still quite a distance and the risk is still low.”

This column is not legal advice. Do not act or trust the information provided. Retain or formally seek advice from an attorney to ensure that your interests are protected.

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