Fan based DIY air purifier

Consumer Reports News: July 15, 2011 12:43 PM

It may seem a little Rube Goldberg-ish but a University of Michigan professor has devised a do-it-yourself air purifier that he claims cuts indoor allergens by 90 percent. Made of a cheap box fan and a furnace filter, the contraption costs far less than some of the pricey air purifiers on the market. “This is a filtration system that you can put together with items from your local hardware store for $25 to $30 and use in your home to cut indoor allergens by about 90 percent,” says Jeffrey E. Terrell, M.D., director of the university’s Sinus Center.

As you can see in his video demonstration, Terrell tapes a 20- by 20-inch whole-house air filter (MERV 13 or higher), which sells for $15, over a 20-inch-square box fan, which you can find for about $12. Using a particle counter, he found that his homemade purifier rid the air of particles nearly as well as an $800 machine.

We haven’t tested Dr. Terrell’s contraption. But by the sheer science of it, the filter-and-fan combination does fulfill the basic definition of an air purifier—pulling air through one or more filters. And the typical fan uses no brushes that could wear away should the fan need to work a bit harder.

If you have a forced-air heating or cooling system, you can replace the existing filter with a whole-house product that dispenses with the cost of a fan. For a single room, however, the do-it-yourself solution is indeed cheaper than the $260 to $300 you’d pay for a top-rated room model in our air purifier Ratings.

We’re about to begin testing of about a dozen more portable air purifiers, assessing their ability to remove dust and smoke and to operate quietly—something no fan-based DIY product can do.

Ed Perratore

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