People in the United States spend upward of 90 percent of their time indoors — inside homes, apartment buildings, schools, and offices. With the threat of COVID-19 looming over every interaction, those indoor spaces (where the virus spreads more easily) can seem loaded with hidden threats.
Fortunately, scientists already have the tools to make buildings better for people and less hospitable to pathogens like the coronavirus. “The science is decades old on all the benefits that come from healthy buildings, including infectious disease reduction,” says Joseph Allen, director of the Healthy Buildings program at the Harvard T.H. Chan School of Public Health. “But these strategies have not been fully deployed in buildings.”
The COVID-19 pandemic may be the stressor that pushes many buildings to adopt healthy practices, and those benefits could linger long after the outbreak fades. “Once we get in the mindset of using our buildings as a tool we can definitely do things to help in the short term, but also in the long term,” says Anja Jamrozik, a cognitive scientist who studies physical environments. “I do hope that it spurs people to action.”
Much of the information that we have about how to make buildings less hospitable to viruses comes from studies on the ever-present flu. All efforts to create healthy buildings start with the basics: the people who occupy buildings and carry the virus. During active outbreaks, minimizing the risk of disease spread in office buildings starts with keeping people out of them and having as many people as possible work from home. Next is identifying the bare minimum number of people who have to be physically present in the building and bringing them back in.
Once they’ve dealt with the people, designers can start trying to make the interiors of buildings as safe as possible. One of the most important solutions is increasing the ventilation and filtration of the inside air, says Kevin Van Den Wymelenberg, co-director of the Biology and the Built Environment Center at the University of Oregon. “The idea is diluting the viral contaminant indoors,” he says. Designers should increase the rate at which air inside is replaced with air from the outside, by windows or other systems, and should find ways to filter the inside air to remove dangerous particles. “It’s two major parts,” Van Den Wymelenberg says.
Most buildings today don’t meet even bare minimum standards for ventilation, Allen says, even though research shows that there are major benefits to meeting or exceeding those standards. One study that modeled the transmission of influenza in a school found that if it met the most basic ventilation recommendations, the rates of flu would drop as much as they would if half the people using the building were vaccinated, even if they weren’t.
Humidity levels in buildings can also be used to fight disease transmission, Van Den Wymelenberg says. Viruses don’t survive as well when humidity inside a building hovers around 50 or 60 percent. When humidity is too low or too high, the influenza virus can spread more easily, for example. In schools and offices, people report fewer respiratory infections and take fewer sick days when humidity is kept in a middle range. But few buildings monitor humidity today, Jamrozik says. “Our buildings often are way outside of that range, and you heating or air conditioning can make the air super dry.”
That’s all got to do with the air you breathe, but another issue is where you sit. People who work in open offices, where desks are close together with no barriers between them, take more days off from work because they say they’re sick than people who have their own office space. People who work in spaces with four walls and a door don’t call in sick as much; they don’t sit only a few feet away from other people, and only breathe in their own air.
No single approach can reduce disease transmission on its own, Van Den Wymelenberg says. “It’s gonna be a layered approach. You’re gonna want to implement multiple measures,” he says.
Arming a building
It’s still not clear how well all this research on influenza and other well-known viruses in buildings translates to the new coronavirus. There’s a lot of pressure to adopt strategies that seem able to stop the spread, especially as economic pressures build for people to return to the workplace. But coronavirus is a never-before-seen threat, and as companies rush to put up plexiglass barriers or install humidity sensors, it’s important to carefully study how well the strategies experts think could help actually do help. “The challenge is that it takes time, and nobody wants to wait right now,” Van Den Wymelenberg says.
Most buildings are in such a rush because they are starting, essentially, from scratch. “It’s a real problem with our current approach to how we design and operate buildings,” Allen says. Luckily, it’s still possible to take an existing building and add in systems that can keep the people inside healthier.
“If you’re starting a new building you have more leeway, but I do think there are things we can do — for example, adding air purifiers or making sure that the filters are changed in HVAC systems,” Jamrozik says. Buildings can also install sensors that monitor temperature, humidity, and air quality. It’s hard for people to tell on their own what the environment actually feels like (if it’s humid or just hot), so objective measures are the best way to make adjustments.
The coronavirus pandemic will absolutely change how buildings are designed, Van Den Wymelenberg says. But he thinks it’s still too early to say which design will rise to the top. “I think there’s a lot of speculation still about what that will look like,” he says. People have been quick to declare the death of the open office, but Van Den Wymelenberg says that there are some benefits to that setup that will have to be weighed against the risk: they enhance social interaction and provide better access to daylight.
In general, any speculation around what healthier buildings might look like in the future is still just a guess. There might be ways to adjust airflow to minimize the risk of shared air in an open plan office, for example, so an office could look the same while still functioning differently. If buildings get healthier by adjusting things like ventilation, the bulk of the updates may be invisible.
Once office designers figure out what really does work, those changes are going to need to happen in all buildings — not just ones where the wealthy live and work. Until this point, interest in healthy buildings has been limited primarily to groups that have more resources, Jamrozik says. But there’s no reason that these solutions should be limited to the select few. Systems that improve air quality aren’t prohibitively expensive and would make a difference for already at-risk people in low-income housing or senior living facilities. It may be even more important to improve ventilation in a call center or meat-packing facility where people can’t work from home than in a white-collar office building that’s already wired for remote work.
“I really do hope that a lot of these solutions become more democratic, because they’re not that expensive, it just takes care and thoughtfulness to add them to the building,” Jamrozik says.
In the United States, it’s usually hard to get people to do things that are designed to prevent problems, which is why healthy buildings struggled to gain traction. The benefits aren’t easily visible or immediate, even though evidence shows they can make a difference for people’s health and productivity.
That’s one reason why, before the pandemic, these designs may have been considered optional. But now, the immediate benefits are clear to anyone worried about catching COVID-19 walking the halls of an office building. Disease-blocking designs are in demand from anyone who has to spend time in a building. And if changes made now stick around for the long term, they could help people feel better indoors even without an ever-present fear of an unknown virus.
“In a pandemic with no silver linings, maybe there’s a glimmer of light here,” Allen says.