DIY air filter to (possibly) reduce exposure to virus
Let’s say your job requires you to be inside with others in a poorly ventilated space. Maybe a windowless room in an aging school building, where the lack of fresh air raises the risk of spreading COVID-19.
Masks will help. Maybe you also want a portable air-cleaning device to help filter particles that may carry the coronavirus. But those can cost hundreds of dollars. Why not make your own?
I built one in October at Hive76, a “maker space” — a member-owned workshop and tinkerer’s paradise located 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. 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.
Here’s how to remove particles from the air with the flick of a switch.
Five MERV-13 filters, measuring 20 inches by 20 inches and 1 inch thick 20-inch window fan, $19 A roll of adhesive weather-stripping
Duct tape
Hold two of the filters at right angles, butting the edge of one up against the face of the other while your partner applies a 20-inch length of duct tape.Add the other three filters, one by one, until you have a five-sided box, leaving an open side to accommodate the fan. The arrows indicating the direction of airflow (printed on the filter edges) should point inward, toward the fan.
Lay the fan face-down on a table, so the back is facing up. Line the outside edge with adhesive weather-stripping, creating a sort of gasket.
When you attach the box of filters in the next step and turn on the fan, the air flow will pull the box against the gasket, helping to maintain a tight seal. Airborne particles are captured in the filters as air is sucked through.
Place the box on the gasket. Seal the edges with more duct tape. Place in center of the room and turn on.
But did it work?
Meyer had a great idea to test the device with an experiment: Sprinkle sawdust in front.
And after a few minutes, we could see a fine layer of dust on the pleated surfaces of the filters. Rosenthal estimates it will last 6 months before the filters become so clogged that the fan can no longer draw an adequate amount of air through them.
Again, no guarantees vs. COVID-19. But that would be the case even if this were a factory-made air-cleaner. No protection is perfect, which is why infectious-disease experts keep stressing the need for multiple precautions when indoors: Wear masks, open windows, and keep your distance as much as possible.