I now own three Vornados and a small army of those in-window units, strategically placed so that no particle of air stagnates in my 1,000-square-foot home. The resulting vortex of moving air eliminates any chance of particle buildup, of a heaviness of atmosphere taking root. Light a cigarette anywhere in my house, and you’ll be dazzled by the flow of the smoke—up and around, through doorways, swirling toward the ceiling and then back to the floor, inscribing elegant arcs through the air—never resting until it finds its way out a window.
I asked Hong whether I was crazy. Was all of this overkill? Sure, the air felt comfortable, but was it really any better? “You solved it intuitively,” Hong said. “From a fluid-mechanics point of view, you are producing a pressure gradient,” which is a fancy way of saying that the air in my house is successfully moving from one side to another. Without a pressure gradient, you end up with what Hong calls a “stable circulation,” in which particles move around and around with no exit route. A big no-no.
One of my rooms has only one window, and therefore only one vent. Hong admonished me. “It’s a very, very bad design to have ventilation in and out in the same place. Much better to have multiple locations.” For those of us renting homes, knocking a new hole in a wall to add a second vent can be difficult. But for businesses, adding vents could be a smart investment.
Thankfully, you can create safer air without going to my extremes. If you can’t afford in-window vents, just crack as many windows as possible. Open doors between single-window rooms to help establish gradients. Do this even with the air conditioner on, or the heater come winter. Yes, it’s less energy efficient, but even one cracked window will slowly replenish stagnant air. Two cracked windows help the air better figure out how to move. You can also augment the quality of air in a single-vent room by adding a HEPA filter, which has been shown to effectively reduce dangerous aerosols.
Read: Can AC spread the coronavirus?
As for fan placement, be intentional. If they’re pointed toward walls, the fans will create pockets where air just loops in circles—that dreaded “stable circulation.” Instead, have fans blow through the room in such a way as to shuffle air toward out-vents or open windows. Since modifying the direction in which an AC blows can be difficult, it is sometimes useful to place fans perpendicular to an AC’s stream. This further helps eliminate any stagnant air pockets the AC may produce because of suboptimal placement. The final results should be clear but subtle: The goal isn’t a wind tunnel, but a gentle sense of active air.
You’ll likely know if you’ve been successful, because—thanks to the vents, the open windows, and the free-flowing air—the room should feel lighter, smell better, and seem far fresher than it did before. Odors should dissipate quickly. And microparticles of spittle should be whisked away at a pace that makes contracting a virus significantly less likely. Your mold will be gone, your head clear, and your life ever safer.