I built one at Hive76, a “maker space” — a member-owned workshop and tinkerer’s paradise, located in a former factory building in Philadelphia.
OK, maybe “built” is the wrong word. I helped hold things while Hive76 president Tom Meyer did most of the work. (He is a biomedical engineer by trade, so who was I to take charge?)
But really, it was pretty easy. All you need is a window fan, some duct tape, and five of those pleated, cardboard-framed filters that are designed for home forced-air heating systems.
Step-by-step instructions are explained below.
We can’t guarantee that this contraption will stop you from getting sick. But if done right, it is a reasonable approach for removing some potentially virus-laden particles from the air, according to air-quality scientists who have been batting around various designs on Twitter.
Drexel engineering professor Michael S. Waring, who has been following the online discussions, agrees.
“This is definitely better than nothing,” he said.
Months after scientists called for the U.S. Centers for Disease Control and Prevention to acknowledge that COVID-19 can be spread by airborne particles — those that remain aloft for a while, rather than settling within 6 feet — the agency updated its guidance to reflect that evidence this month.
Here’s how to remove particles from the air with the flick of a switch.
An easy approach tried by some do-it-yourselfers is simply to slap one filter onto a window fan, attaching it with big rubber bands and sealing the edges with duct tape. That design costs less than $20, assuming you already have a fan and some tape.
But forcing air through just one filter could put a fair amount of strain on the typical fan — especially if you run it for hours at a time, said Meyer, the Hive76 president.
“You’ll burn out your motor,” he said.
Better to increase the surface area through which the air travels by building a box of five filters, said Jim Rosenthal, past president of the National Air Filtration Association and chief executive officer of Tex-Air Filters, a filter manufacturer in Texas. That way, the fan is forcing the same amount of air through a greater number of “pores,” easing the load on the motor. Rosenthal came up with that design in consultation with Richard Corsi, an engineering professor at Portland State University, in Oregon.