[h2odragon]

If you dont get the allergy reactions without them; then they're not doing you any good, i'd say.

You might be able to reduce the maintenance by concentrating the filtering effort on the places you are; put one right by the bed, your desk, etc. Only run them when you're actually there.

More filter area and thickness gives more time between changes (but also more time for stuff to grow in the filter, if you're in a humid place). Commercial things are always tiny little things anyway; build your own. Go get some of the washable 20x30 filters and cardboard, duct tape, and a fan. If you want to get really fancy you can get a speed controller and run the fan at low speed so its quiet.

[alister]

> Go get some of the washable 20x30 filters and cardboard, duct tape, and a fan

Here's a Wikipedia reference to one very effective design:

https://en.wikipedia.org/wiki/Corsi%E2%80%93Rosenthal_Box

It's just four 20x20-inch HEPA filters from a hardware store taped together as a cube with a 20x20-inch box fan on top. I remember reading (here on Hacker News) about someone's experimental analysis that this simple design was more effective than most commercial air purifiers.

The only downside is that a typical box fan is quite noisy even at the lowest setting.