Comment by julianlam

After watching this segment, I immediately bought a 20" box fan, a 20x20 MERV 11 filter, and put one together.

It kicks the pants off of air purifiers twice the price and it moves a lot of air through. Best investment ever.

CBC was testing CADR, which is one metric among others, but an important one if you're looking to clean a room's air, fast.