Ask HN: Should I stop using air purifiers? | Hacker News Reader

Ask HN: Should I stop using air purifiers?

I've been using 3 air purifiers for about a year now. The problem I have with them is that they are so high-maintenance (much more than I expected). If I don't replace a filter after two months or less, I will get allergies (stuffy nose) because of the particles getting re-released back into the air. Has anyone had similar experience and/or decisions? I've been following the advice of just adding more ventilation and cleaning the house more often. I honestly find that less annoying.

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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.

> 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.

With some air sometimes you just have to accept that without some high-maintenance effort, there would be no clean air at all.

For any one person fresh natural outdoor allergens like pollen may or may not be better or worse than accumulations of indoor pollutants. And there can be major differences at different times of the year.

If you're extremely sensitive to spent filtration media, that could be a strong sign that the filtration process is being fairly effective.

Can you use 1 bigger one instead of 3?

You may also not need to run them all the time. Perhaps only run them if the air quality is bad or at night when it's too cold to keep the windows open, etc

I once saw a video of someone attaching one of those HEPA filters to a box fan with tape and it works more or less just as decently.

Alternatively, have you done maintenance on your air ventilation system in your house? They should have HEPA filters as well. That should help.

You can also do a mold test. A simple one is leaving a cup of water near a wall and wait a couple days to see if mold grows on it from a free-floating spore.

I tried doing the DIY HEPA filter because I was poor. It's not much better than just buying a cheap filter that's basically the two put together. It was okay but not too effective.

Getting rid of moss cleared up most of the trouble. And antihistamine (Vitamin E) shots.

> I once saw a video

There have been several submissions of (various? or the same?) DIY air filters.

The trick to finding them on hn.algolia.com appears to be to use 'air purifier' rather 'air filter' (which kind of suggests that they're submissions about the same one):

https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...

Or using Google site search (the trick here being to search for "points by" to limit results to the toplevel submissions (and incidentally submissions with not exactly 1 point :)): https://www.google.com/search?q=site%3Anews.ycombinator.com+... - «site:news.ycombinator.com fan filter "points by"»

If your home has ductwork, you can add a hepa filter to the circulation system. Mine uses a deeply-pleated material that must be 40+ sq.ft. feet in area, on an always-on blower system. I change the filter yearly, should change it more often.

why do you need them? clean and ventilate and if necessary move.

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