COVID-19 and offices: Could the coronavirus be transmitted through the air?

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In a pandemic, an office tower is a minefield of potential risks. The front door, with the handprints of hundreds of people. The elevator, usually crammed with people. The office door, the washroom, the cubicle, the tap in the office kitchen. Each of these represents a potential site of transmission for COVID-19, and employers are thinking hard about how to keep the virus from spreading here.

But what about the air? What if you can catch the virus simply by breathing the same atmosphere as your colleagues across the floor? This is possible; just how possible is still not clear. But if COVID-19 proves to be highly contagious in this manner, it might endanger legions of employees, and create a technical problem for building owners, managers and engineers that is difficult to fix. Or even impossible.

Could the air within offices spread COVID-19? “Right now, there’s no clear proof,” said Tony Dingman, a mechanical engineer and partner at the Mitchell Partnership (TMP), a prominent Toronto consulting firm. “There’s also no clear proof that everything is okay.”

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So far, the main forms of COVID-19 transmission are through direct physical contact or what scientists call droplets – the larger particles of liquid that can be expelled from a person’s mouth and travel short distances. But aerosols, microscopic particles light enough to be carried by air currents, could also pose a danger.

A recent study suggests that while airborne transmission of COVID is not well understood, “engineering controls” could help limit infection risk. This is where Mr. Dingman – and the entire commercial real estate sector – have to start paying attention. “We’ve been working with many of our clients to understand this pandemic and the safety of their staff,” Mr. Dingman says.

Those clients include some of Canada’s biggest financial and tech companies. TMP is the mechanical engineering firm for some of the largest office towers in Toronto – now including the 2.9-million-square-foot CIBC Square project for Ivanhoé Cambridge and Hines, and the 36-storey office building at the Well, which will be Shopify’s Toronto base. (TMP advised The Globe and Mail on the interior construction of its office space.)

The problem is “recirculated air.” This is what flows through most offices and other large buildings, except hospitals. Fresh air enters a building, is heated or cooled, humidified or dehumidified, and then moves around in a circuit, being periodically freshened up with new air from outside. Under normal circumstances, 80 to 85 per cent of the air in an office is recirculated. What you and your colleagues breathe out is what you and they are breathing in.

With a disease that is highly contagious through the air, such as tuberculosis, this is disastrous. Early-20th-century hospital wings were designed to provide lots of fresh air for this reason; an obsession with fresh air and light became part of Modern architecture.

Ventilation systems can make a disease spread. While studying an early example of airborne transmission of COVID-19, in a restaurant in Guangzhou, researchers concluded that it was likely spread through droplets, pushed along by a strong air conditioner fan from an infected person’s table to the tables nearby.

The broader possibility of infection through the air, even over longer distances, has not been ruled out. Some scientists think it is likely.

And this could pose a very clear threat to office space. While the largest buildings often have their air space divided into discrete sections – for different tenant spaces – each of those can house hundreds of people. And if the virus that causes COVID-19 proves to linger in the air and remain infectious, it might be possible for any one person to infect others.

That is an extreme scenario. If the science proved it out, “I’m guessing that, as a society, we would question the idea of going indoors in shared spaces,” Mr. Dingman said.

For the moment, ventilation experts are suggesting specific actions to reduce risk. The basic recommendations: Provide more fresh air; increase the level of air filtration and change filters more often; control humidity in the air to a moderate range.

In some cases such changes are possible. Allied REIT, a major Canadian office landlord, says it has followed those recommendations – including providing 100-per-cent fresh air “or very close” during March and April, according to Doug Riches, Allied senior vice-president for national operations. That’s no longer the case, however, now that high temperatures and humidity would make offices unmanageably hot. “We’re operating week by week,” Mr. Riches said. The company is working with medical consultants and studying scientific reports on a daily basis. “This is uncharted territory,” he said, “and we’re relying on the medical profession and the engineering profession to advise us.”

How are employers treating this question? Representatives of two major Canadian banks declined to comment. Employment lawyer Hena Singh of the Toronto firm Singh Lamarche, who is advising corporate clients on their return to work, says airborne transmission has not come up in those discussions. She suggests that assessing risk should involve conversations between staff and managers. “The bare level of risk management is what the province recommends,” she said. “There’s science behind it and they’re being very conservative to ensure that restrictions are in place to protect employees.”

But current guidance from Ontario’s Ministry of Labour offers no specific recommendations: only “best practices,” including increasing fresh air.

That may not always be possible. Allied’s Mr. Riches says that his company’s portfolio is heavily weighted to new buildings with advanced air handling systems, where controlling airflow and filtration is doable. In many older buildings – which constitute a majority of Canada’s office space – “it could be impossible,” he said. Mr. Dingman, the engineer, agreed.

And running air-movement systems 24/7, while making air-conditioning and heating systems work harder, is “incredibly expensive, in terms of energy and in terms of money,” Mr. Dingman added.

How much of this is worth doing? How much will changing humidity, replacing filters, and pulling in more fresh air stop COVID from spreading? Mr. Dingman is not sure. “I’m not the world’s most popular engineer right now,” he said, because his firm doesn’t believe the science is clear enough to dictate major physical changes. “We don’t know which direction to push to be certain that we’re helping,” he said.

“People want us to rescue them. They want a warm blanket around their shoulders. But the world just got more complicated.”

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