I felt similarly, but I have a family member who is bed-bound, there’s some asbestos removal going on, so I decided to take the plunge.
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.
(A few minutes after posting this, morning rooftop construction started. Sounds of saws and drills buzzing, large objects and beams being dropped directly overhead. Air purifier just kicked into high gear. Yes, I’m definitely into this thing.)
I’m a big fan of thewirecutter, and I reference them frequently on most things I’m buying. But for HEPA air filters, I don’t feel like they test the models that I feel are best for someone with asthma, or other similar breathing problems.
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 "air quality" in the form of particulates… it does turn off after a while. 15-30 minutes after cooking, one or two after sweeping, etc. Presumably it's triggered by no longer detecting particulates in the air, one would have to be fairly conspiracy-minded to suggest that it's working on some kind of timer (and can tell the difference between dust-timeouts and gas range waste timeouts)… I figured this was too obvious to point out, even given the sort of pedantry we get around here.
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.
How does it compare to a control? If the pollution stops (eg you stop cooking) the particulates will settle on their own. You'd expect the count to go back down to normal over time. How much faster does the air purifier cause the particulate count to decrease?
Yes they do. But you need a sufficiently powerful one to be able to circulate the air in the room enough times per hour, more that the circulation that occurs through the doors, windows and even walls.
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.
Not sure where you live, but if air in my room circulated once in an hour, with doors/windows closed, I'd consider it way too much. We have winters so people tend to plug holes.
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.
Yes, they definitely do, although to a various degree of effectiveness. If you get a Xiaomi Mi Air 2, for example, it will be very effective. If you get a Dyson fanless thing, not so much.
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.
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.
I decided to buy one when the smoke from the Sydney bushfires blanketed my town.
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.
A few years back I had to temporarily move back to my parents while getting a new place. It had been years since I'd used my room, and it had been neglected a bit.
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.
they probably work around a small area where they are placed, but particulates outside of that will be unaffected and ultimately fall to the ground ready to be disturbed and recirculated as dust. I'm under the impression that for something like this to work, you would need to feel the air current at every point in the room, like a light breeze
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