If you have allergies or live in a city, you should consider building one of these relatively inexpensive high performance box fan air filters.
http://amzn.to/2rebmWK for the filters used here
Lasko fan, (seems hard to find) http://www.laskoproducts.com/20-metal-box-fan-model-b20725/
I constructed mine a year ago, in about 30 minutes last year, using the best filters I could find and simple duct tape for construction (which needs to be redone when you replace the filter).
After a year of continuous operation with no issues, and basically not paying any attention to it, but as spring arrives of late I've noticing the air getting stale, and my allergies getting worse, thought it was high time to replace the filter, and wow indeed it was, look at the crap there, especially impressive as we have hardwood floors (not carpet) I was half tempted to try and do a microscope on the dust but it was really too horrifying, came off in a poof when putting it in the trash.
It's constructed from
- a heavy duty Lasko Industrial Fan,
- 3x filtrete 20x20" filters
- a variac to help control speed and volume, as even at the lowest setting the powerful fan is WAY too loud/much air.
I've actually grown very fond of it's white noise generation, and helps living in a busy noisy neighborhood cover up the cars, sirens, dogs, helicopters, neighbors etc.
I tried several things looking for clean air, this diy approach has the advantage that the filters themselves are super easy to find, standard size, commodity prices with a wide range of options in what they filter. I had a proprietary filter prior and they basically stopped making it and the replacements were retardedly expensive, and small. The size of the squirrel fan could in no way conceivably match the volume of air one of these fans could push...or technically pull, which is how this one works.
I chose a box design after using an wind speed meter to figure out what was the least resistance, of 1x flat, 2x in a triangle (harder to cover and odd to place) , 3x in a box like shown. It works fine this way, doubles as a table, though I am switching to a single filter as the box takes up quite a bit of space, and would like space back for other projects
Ideally like something that works with the ceiling fan, and may try hacking something there, but for now this works fine.