[yalue]

One thing the article doesn't seem to mention is noise. I've found that the "actual" air purifiers seem to be much quieter than box fans. Perhaps if you had greater control over the box fan's speed you could get the noise down to a comparable level, but I doubt the cheap type of fan used in the article is capable of such a thing.

[jerlam]

Yep, the DIY may work in an emergency but there are good reasons like noise, size, and power usage to get a commercial product if you're going to be living with it.

The layout of the purifier is important in a crowded space - the DIY requires open space both in front and behind for good airflow, but the commercial ones have a front intake but vent straight upwards, so you can shove it against the wall. No one is going to put their air purifier in the middle of the room away from other furniture.

[storyinmemo]

Indeed, the thing that keeps me happy with the Coway 400 I've got is the very small power use when particulate is low and the automatic ramp up when it goes high. My fan I keep near my bed for my own comfort pulls 30 watts. The Coway pulls something more like 5 watts in low use. Expensive up front but low ongoing cost and 4 years running now.