I use a box fan with filters taped to each side. You want to do both sides or the air gets pushed/pulled around the edges of the blades, rather than going through the filters.
A small DIY air purifier
91–100 of 178 posts
Re: A small DIY air purifier
#92This basically looks like a mini Shop-Vac. If you own a Shop-Vac (a wet-dry vacuum, generically), could you just turn it on without the hose? It would draw much more power, but presumably would work much quicker, and so may end up being more efficient.
Of course; ditto any vacuum cleaner, AC with filtration, etc.
It's just airflow + filter, which is why DIYing them is so popular.
Re: A small DIY air purifier
#93Air quality test before and after or it doesn't work. I am very suspicious with regards to air purifiers. Have you ever seen real HEPA filter? It is thick and it is quite difficult to push air through it. I can't imagine small PC fan that is designed to push air through UNOBSTRUCTED space will make any significant flow of air. I have spent some time with the guys who build PCs and who know great deal about fans and o…
+1. Together with a test in the same environment without a purifier at all. PM count drops down to almost 0 in a room with closed windows with a breathing person inside. Lungs of a person act as a perfect purifier.
LOL. Isn't that exactly the reason why you want a Purifier .
Re: A small DIY air purifier
#94May as well ask here: do air purifiers have meaningful health benefits for generally healthy people? I get that you change the filter and it's filled with grey muck and that's gross, and that the filters change particulate content in air, but is there good evidence that doing those things improves health if you don't already have some sensitivity to air pollution or live in a highly polluted area?
I don't know if "Lung India" is a great journal, but the "Efficacy of indoor air filters" section of this paper [1] doesn't offer much support. All studies are pretty small and focused on people with asthma or pet allergies. The few studies of populations without such conditions show what look to me like minor improvements, e.g. a ~5 mmHg drop in blood pressure. These aren't super strong studies though.
The argument that pops up in pro-air-filter pieces draws a line through "air pollution can be a big health hazard" (true), "air filters reduce some particulate content in the air" (true), and "air filters improve health" (unclear). But the "big health hazard" conclusion seems to come from intensely polluted environments, like poorly-ventilated homes that use kerosene, or areas with lots of smoke. For a generic first-world home I can't find much evidence.
Re: A small DIY air purifier
#95Earlier quoted context omitted.
+1. Together with a test in the same environment without a purifier at all. PM count drops down to almost 0 in a room with closed windows with a breathing person inside. Lungs of a person act as a perfect purifier.
> Lungs of a person act as a perfect purifier. Is that good? I mean, of course it's good that PM doesn't just pass straight into our bloodstream, but isn't our lungs doing the purifying exactly the thing that people try to avoid with mechanical air purifiers?
It is bad of course! PM does pass straight into our bloodstream.
I was just talking about the test setup. A test of any purifier should be compared to a test with a person in a room without purifier. Otherwise those results are not significant.
Re: A small DIY air purifier
#96I don't know how effective they are compared to these devices, but I much prefer to keep plants with air purifying qualities. NASA did a study on a variety of air purifying plants in 1989: https://ntrs.nasa.gov/search.jsp?R=19930073077
Last time I checked, most of those aren't safe for house pets either :/
Re: A small DIY air purifier
#97This is a really cool project but frankly you can do it a lot cheaper. Find the cheapest box fan you can find, and find the cheapest HEPA filter you can, and strap the HEPA filter to the front. To improve air purification even futher, slap an activated carbon filter on the front too, and your air purifier now filters VoCs! For cheap Activated Carbon Filters, look into the kind used for Aquarium filters. They'll work…
I have smartairfilter's Cannon purifier. As all those standalone purifiers it works only with windows completely closed.
I went for ventilation systems that take air from outside, filter it and then bring it inside the room. Namely Xiaomi MJXFJ-300-G1: https://www.xiaomitoday.com/xiaomi-mijia-air-purifier-mjxfj-... I've installed one in every bedroom.
Re: A small DIY air purifier
#98May as well ask here: do air purifiers have meaningful health benefits for generally healthy people? I get that you change the filter and it's filled with grey muck and that's gross, and that the filters change particulate content in air, but is there good evidence that doing those things improves health if you don't already have some sensitivity to air pollution or live in a highly polluted area? I don't know if "Lu…
I would assume the majority of people (in the US, anyway) are already filtering their air enough through their central air to make any additional "room-sized" filtering negligible.
Similarly they make some very dense HVAC filters if standard ones aren't catching the level of particles you need, so I'm not sure what the purpose of these filter-fan things are for most people.
Re: A small DIY air purifier
#99I don't know how effective they are compared to these devices, but I much prefer to keep plants with air purifying qualities. NASA did a study on a variety of air purifying plants in 1989: https://ntrs.nasa.gov/search.jsp?R=19930073077
You would need to live in an indoor rainforest (approximately 680 plants for a typical house) to see an effect on air quality, a spider plant in the corner isn't doing anything: https://www.youtube.com/watch?v=AmeiXikh0v8
*to see a similar effect on air quality as mentioned in the study
Re: A small DIY air purifier
#100I'm in Bangkok right now which is having a smog issue right now due to pollution and burning in the rice fields across the country. It's a shame that we're buying/making air filters instead of working on policy and cleaner methods of doing work--so now the poor and the wildlife can't afford to have clean air.