Across America, buildings are opening back up — offices, schools, theaters, stores, restaurants — even as evidence mounts that the coronavirus can circulate through the air in a closed indoor space.
That means a lot of business owners and facility managers are calling up people like Dennis Knight, the founder of Whole Buildings Systems in Charleston, S.C., asking what they can do to make sure their building doesn't spread the virus.
Knight has some disappointing news.
"You cannot guarantee that someone might not get sick," he says.
But there are ways to reduce the risk. Knight is on the epidemic task force of ASHRAE, the organization of heating, ventilation and air conditioning professionals, which has assembled guidance for building operators on how to do exactly that.
But Knight warns building managers to be cautious of anyone selling them an air-purifying device or super-strong filter with an absolute guarantee that it will stop the virus.
"That's when the hairs stand up on the back of my neck, and I get really suspicious that ... I'm being approached by a snake oil salesman," he says. "Really, you've got to do everything. And you've got to do it with diligence. And even then, there's no guarantee."
"Everything" means covering the basics — making sure a building's HVAC system is up to code and correctly maintained. It means buying more efficient air filters (but not too efficient for your system; many HVAC systems can't handle the most effective filters). It means pulling more fresh outdoor air into the system. It means running the system for more hours in the day, including flushing cycles before or after people are inside. It means considering portable units with HEPA filters or UV lights to sanitize air.
And it could mean opening windows and doors — or if there's one room with really poor ventilation, maybe not using that room at all.
There's a lot to consider. And as the science on COVID-19 has been evolving, the right actions haven't always been clear. Now, some building operators are intimidated or overwhelmed by the scale of the challenge.
"It's tricky and it's confusing and in large part, it's scary," says Kathleen Owen, an air filtration consultant in Cary, N.C., who also works with ASHRAE.
"And the answer to it is, first, don't panic. Second, do what you can," she says.
Owen compares it to face masks. An N95 is ideal, but not available for everyone. A cloth mask is less effective, but much better than nothing.
Similarly, if a building's HVAC system can't handle an extremely efficient filter like a HEPA or a MERV 13, then install the best filter that the system can handle. And don't forget all the other ways to reduce the risk, such as running the system longer or pulling in more fresh air.
Raj Setty, an engineer in Washington, D.C., has been advising schools and businesses on how to reopen safely. He says he really wants to see more institutions thinking creatively about ventilation. Like, can schools set up tents in their fields? Can they rearrange schedules to take breaks in the winter, and hold classes in the summer, if that makes outdoor classes more feasible?
"Maybe you go virtual when it's over 90 degrees and then when it's under 90 degrees, you just hold class outside," he says.
When going indoors is unavoidable, Setty's company has designed a spreadsheet engineers and others can use to help think through the different options for improving air quality and reducing risk, from investing in ultraviolet disinfection to simply reducing the number of people indoors.
Setty acknowledges there's no way to get the risk down to zero and that scientists are still working to understand the virus. But while science continues to carry out research, he says, it's up to engineers to apply what we know.
When people have to gather inside a building, Setty says there's no real downside to bringing in fewer people, better air filters and more fresh air.
It might cost more money, but better air quality is a boost to human health — and not just during a pandemic.
LEILA FADEL, HOST:
Experts say one crucial element in the fight against the coronavirus is invisible. It's indoor air quality. The risk of transmitting the disease is much higher if people gather indoors in poorly ventilated spaces. What does that mean for schools and businesses that are reopening? NPR's Camila Domonoske reports.
CAMILA DOMONOSKE, BYLINE: Dennis Knight talks to a lot of building owners who want one thing - one thing he can't give them.
DENNIS KNIGHT: You cannot guarantee that someone might not get sick.
DOMONOSKE: Knight is with ASHRAE, an organization of heating, ventilation and air conditioning professionals. The group has set guidelines for preventing the spread of COVID-19 through indoor air. And Knight says, watch out for anyone selling a device and promising it will eliminate the risk from the coronavirus.
KNIGHT: That's when the hairs stand up on the back of my neck. And I get really suspicious that it's - I'm being approached by snake oil salesman. Right?
DOMONOSKE: There is no silver bullet, he says. Big buildings like offices and schools need better air filters in their HVAC systems, and they need better maintenance and more fresh air coming in and fans running for longer.
KNIGHT: You've got to do everything, and you've got to do it with diligence. And even then, there's no guarantee.
DOMONOSKE: The guidance hasn't always been clear on what to do. For a while, experts couldn't even confirm if the disease could be spread through the air beyond 6 feet. Now there's growing consensus that is a risk. Kathleen Owen is an air filtration consultant in Cary, N.C.
KATHLEEN OWEN: It's tricky, and it's confusing. And in large part, it's scary.
DOMONOSKE: It's tricky and confusing in part because every building is different. And the best, most effective air filters - many heating, air conditioning and ventilation systems can't handle them.
OWEN: The answer to it is first, don't panic. Second, do what you can.
DOMONOSKE: Think about how we wear masks. An N95 is ideal, but not everyone can get one. So a cloth mask is better than nothing. Similarly, Owen says, if the most effective filter is not an option, use the best filter your machine can handle. Run your system for longer. Consider adding portable purifiers. And don't overlook the low-tech solutions like opening windows and doors. Raj Setty is an engineer in Washington, D.C., who says schools and businesses need to start thinking creatively. Like, can you set up a tent?
RAJ SETTY: Maybe you go virtual when the temperature is over 90 degrees. And then when it's under 90 degrees, you just hold class outside.
DOMONOSKE: His company has designed a spreadsheet other engineers can use to help think through the different options for improving air quality and reducing risk. He pulls it up to demonstrate it.
SETTY: Then, I put in the ventilation per person. Then, there's total air changes...
DOMONOSKE: And he starts plugging in different kinds of changes.
SETTY: So now, as an engineer, I'm going to go, I'm going to change the filters.
DOMONOSKE: A number representing risk goes down.
SETTY: Maybe I will go down to half the population.
DOMONOSKE: The risk goes down some more.
Setty knows that scientists are still discovering new things about this virus. But, he says, engineers need to use the data we have to make decisions right now.
SETTY: Look. Engineers apply. Scientists do science. We have to give you a solution. That's it.
DOMONOSKE: And when being outdoors isn't an option and people have to gather inside a building, he says there's no real downside to having fewer people, better filters and more fresh air. It might cost more money, but improving indoor air quality is good for human health, pandemic or not.
Camila Domonoske, NPR News.
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