Build a do-it-yourself home air purifier for about $25 • Hacker News Board

Re: Build a do-it-yourself home air purifier for about $25

#331

Post by morganvachon » Thu, Nov 15, 2018, 1:33 AM UTC

endymi0n wrote: post #241

morganvachon wrote: post #237

Earlier quoted context omitted.

In my experience a one-two punch with chloride to kill the mold quickly, followed by a dousing with distilled white vinegar, results in a good short and long term solution for surface mold.

Safety advice: If you decide to try this at home, please keep in mind that mixing chloride based cleaning agents with an acid will release chlorine, which is toxic enough to have been used as a WW1 weapon.

I guess I didn't realize someone would try this without letting the chlorine evaporate first. I should have worded it better: Chloride to kill the mold on contact, let dry, then vinegar to keep the mold away.

Re: Build a do-it-yourself home air purifier for about $25

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Post by rustychris » Thu, Nov 15, 2018, 2:29 AM UTC

patrickbuckley wrote: post #326

Does anyone know if this type of setup would be good for smokey air from California wildfires?

It works - we measured 25 down to 5 ug/m3 drop over 2 hours in an oakland townhouse. Measured with hobby grade (pms5003 from adafruit) hardware, so absolute numbers probably not that accurate, but the effect was clear.

Re: Build a do-it-yourself home air purifier for about $25

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Post by sometimesage » Thu, Nov 15, 2018, 3:05 AM UTC

LeoPanthera wrote: post #57

Huh! I independently "invented" this myself a couple of days ago when the Camp Fire blanketed the bay area in smoke. I got a 20x20 filter and some duct tape from Home Depot and a box fan from Target. (After discovering that Home Depot only sells fans in the summer.) I don't think I was the only one, though. HD was doing a brisk trade in 20x20 filters, and I think I bought the last box fan at any Target in the entire…

When you decide to change out the filter I recommend using cheap painters or kraft tape instead of duct tape. I found that painters tape removes easily and tends not to leave adhesive behind.

Re: Build a do-it-yourself home air purifier for about $25

#334

Post by kijin » Thu, Nov 15, 2018, 4:31 AM UTC

nvarsj wrote: post #302

kijin wrote: post #282

Earlier quoted context omitted.

As someone else mentioned downthread, you need to maintain a rather high temperature (around 25C/77F) in order to reduce the relative humidity enough. This might or might not have been feasible given OP's budget, heating arrangements, and general preference. I for one would not want to live in such a hot room for a whole season even if I could afford to. I keep my room cooler than that even in the summer!

Hmm, my house during winter is usually between 18-20. If I keep the window vents closed (most UK houses have vents above the windows specifically for this reason), I get a lot of condensation around the windows which gets mouldy. Leaving those vents open makes all the difference - no condensation, no mould. Also the house humidity seems to stay under 50% with the vents open.

Yup, that's a normal house. Doesn't work in a basement, though, unless it has a vent or small window above the ground.

Re: Build a do-it-yourself home air purifier for about $25

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Post by thewhitetulip » Thu, Nov 15, 2018, 6:23 AM UTC

cestith wrote: post #322

thewhitetulip wrote: post #163

Edit: plants do nothing to particle matter in air they can soak up co2, benzene, formaldehyde etc but do ample resesrch before placing plants in your bedroom. Typically snake plants are fine in bedroom as they don't give out CO2 at night. There is no need for an air purifier if you have ample light in your room. Just plant a few indoor plants Peace lily Rubber plant Snake plant Spider plant Aloe vera Money plant Orch…

Orchids and rubber plants from that list, at least, are fairly common allergens themselves.

I didn't know that! That's still fine though, there are a lot of other n9n allergenic plants which one can use. And if nothing can be used then we can use commercial purifiers too

Re: Build a do-it-yourself home air purifier for about $25

#336

Post by hermosa » Thu, Nov 15, 2018, 7:26 AM UTC

egghat wrote: post #261

Check out the blog http://particlecounting.tumblr.com/ The writer has tested a lot of combinations of fans and filters (Simple, HEPA, Activated Charcoal). It's astonishingly easy to build a combination that costs way less than a "professional" Air filter. The writer has put his findings into a "social startup" that builts these simple, but very effective airfilters in some developing countries: https://smartairfilter…

I use the SmartAir filter setup in Shanghai. It works great and the founder's blog is very useful. I'm glad to support the project.

Re: Build a do-it-yourself home air purifier for about $25

#337

Post by logfromblammo » Thu, Nov 15, 2018, 3:22 PM UTC

pers0n wrote: post #330

logfromblammo wrote: post #311

Earlier quoted context omitted.

Chloramine is responsible for the classic "swimming pool smell", as the chlorination in the pool reacts with urine, sweat, and other nitrogen-containing organics. Chloramine is a less effective disinfectant than free chlorine, and more irritating to swimmers, and diffuses out of the water more slowly, so this is why you shouldn't pee in the pool, and why you should rinse off in a shower for a minute before entering.…

My bathtub in my apartment would smell like that after using Tilex. I don't pee in the tub either, so I guess it can only be from sweat.

Chlorine can react with about anything that contains ammonia or amines to form chloramine, so shampoos, lotions, shaving foams, or conditioners could also be responsible. Amino acids are named thus for their amine groups, so anything containing proteins or protein fragments will react. Amine oxides and triethanolamine are used as surfactants in cosmetics. Sweat is unlikely to be the culprit. Check the ingredients in your cosmetics.

Re: Build a do-it-yourself home air purifier for about $25

#338

Post by stevenwoo » Thu, Nov 15, 2018, 4:34 PM UTC

wenc wrote: post #94

I wonder: if one is generally healthy and the air quality is unproblematic, should one get an air filter? Does air filtration potentially lower long term immunity and make us less tolerant to particulates? I worry about the long term effects of being “too clean”, that is, I think there’s something to hygiene theory of disease. The body needs small stressors and perturbations in order to thrive.

This article references a more recent London study but mentioned is a more extensive California study of children. TL;DR; One really, really should not live/work any closer to a road with (18 wheelers) traffic than one has to, for children it is paramount - I think all schools in Southern California close to a freeway have filtration systems for this reason.

https://www.theguardian.com/environment/2018/nov/14/diesel-p...

Re: Build a do-it-yourself home air purifier for about $25

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Post by 51lver » Thu, Nov 15, 2018, 8:57 PM UTC

Kadin wrote: post #122

51lver wrote: post #21

I used a very thick (4") filter rated for smoke particles when the wildfires this year blew their smoke down to Seattle. The filter went from white to a very interesting shade of grey in 3 days. Wife was able to sleep again though, so it does work very well in my experience. (20x20 fan, filter on intake side)

Out of curiosity, where were you able to find the big 4" thick filters in the 20x20 size? I wasn't able to find anything other than the usual 0.75 thick furnace dust filters in 20x20 for a box fan.

Ace hardware. It was not cheap.

Re: Build a do-it-yourself home air purifier for about $25

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Post by marco1 » Thu, Nov 15, 2018, 10:51 PM UTC

kijin wrote: post #159

benbojangles wrote: post #85

I built my own air purifier in 2016, living in London, I was living in a basement and was having breathing problems due to mould. My landlady was gaslighting me at the time, so I built the air purifier. It worked for a while but mould spores cling to the paper filter and eventually grow into the filter material. I think Dyson uses glass fiber filter to stop this problem. My filter helped a lot, but eventually I had s…

A wet paper filter is the perfect place for mold to stick to and send spores all over the place. If you have a mold problem where you live and can't move out of the place, you need an air filter and a dehumidifier. Unfortunately, it's hard to jerry-rig a dehumidifier on the cheap. If you were in London in the winter, it might have been more practical to turn up the heat to keep the room as dry as possible.

Could mold grow inside of a dehumidifier as well? I mean, water is constantly passing the components inside. Or does mold need organic material (such as the paper inside the DIY filter) and thus will not grow on the dehumidifier that consists largely of plastic and metal?