Do air purifiers really work? I always have impression they're just sham, or at least placebo.
I can vouch for their ability to detect impure air. If I start cooking anything, it switches on within seconds. It’ll turn on within about three minutes of sweeping the floor. And if the detectors can turn on when the air is dirty, it stands to reason that they can tell when the air is clean and they turn off as well.
Shortly after getting this, some intriguing news surfaced regarding the installation of air filters in a California school (due to a gas scare) which resulted in a jump in test scores vs other schools in the same district.
I am not a scientist, but I’m feeling pretty convinced about the efficacy of these things.
https://www.vox.com/2020/1/8/21051869/indoor-air-pollution-s... https://news.ycombinator.com/item?id=18219391
We have several IQAir units, of at least a couple different models. None of them have sensors to automatically ramp up the filtering when they detect pollution, that would be nice. But according to the air quality sensors I have in the house, they do an amazingly good job of filtering the air, at least if you turn them up to high enough levels.
I have yet to see demonstrated clear benefit of the units with activated charcoal filters for removing VOCs from the air, but my gut feeling is they do help in those areas where VOCs are a concern. Not all parts of our house needs that, however.
Having four furballs does greatly increase the dander and other allergens we have to deal with, but we wouldn’t give them up for anything, so the IQAir units at least make our lives a bit more livable. Especially during “Cedar Fever” season.
If you're referring to some quality of the air beyond particulates… well that's not what a HEPA is even for, is it? I could be mistaken.
Eco-rated houses have a circulation of about 2-3 times per hour. Older houses that are well insulated are about 5-6 times per hour. The purifier needs to be powerfull enough to spin the entire air volume couple of times faster than the natural circulation.
If your windows and doors leak too much, or if you open them too much, or if you burn oil / light up cigars too much and produce smoke then it might be pointless.
I live in one of the cities where the pollution is regularly at the top 10 in the world, and the unit I have is able to reduce the pollution inside to a level that is 5-6 times lower than outside if it runs constantly in a mode that is like 30% of the power. It could do better, but it would be too loud for me.
You're not talking about HVAC, are you?
Nevertheless, I do know people living in leaky homes/building, and they do get >1 exchange/hour.
In general, there is no escaping physics: you need to move a large quantity of air through something that traps dust particles. The low-tech solution of a fan and a HEPA filter is a very good one, but I would suggest getting a filter that traps PM2.5 particles as well.
Or read the specs and compare with norm
Any sources on that? I have one and I swear by it. They have a glass HEPA filter and a carbon filter. I'm not quite sure how much air it moves but it's enough to scrub the air of my two floors apartment when someone smokes indoor. It's not really fanless per-se, it's a turbine in the base. You are simply moving the blades down into the base and away from the output area.
In my bedroom I could see and taste the smoke. The air purifier struggled, but it cleared the air around my computer quite well. I have dividing curtains in my room that I was able to close, which made it easier on the purifier.
All in all I think it was definitely worth the buy. FWIW I picked up a secondhand Kogan SmarterHome air purifier for AUD$60.
First days I started coughing a lot when staying the room for a bit, and I woke up quite stuffy in the morning. Got me an air purifier with HEPA filter and let it run at max setting while at work. After running it a few days like this, I didn't have any more issues.