[iSloth]

I've never experienced an air purifier, what's the general consensus?

Do they make a difference? Perhaps a placebo? A must have?

Genuinely interested if I'm missing out - For what it's worth I do live right on a main road in the UK, so I expect there is some level of pollution in the air.

[hammock]

I was so skeptical. Living in SF in 2018(?) during the wildfires, my apartment was drafty and I’d come home from work to a hazy indoor environment. I’d wake up with a sore throat and that’s what got me to take action (can’t sleep with an n95 on)

I got the cheapest air purifier from Amazon and just put it on my bedside table. After one night my sore throat was gone.

As simple as these machines are, they do work.

[CoastalCoder]

I can see how an air purifier makes sense in that 2018 scenario.

I guessing that the benefits are less certain in more typical cases.

[imajoredinecon]

> that 2018 scenario

It’s a little hard to believe if you haven’t lived there recently, but basically the entire US west coast now has an annual fire season where you can expect at least several days of air quality in the “unhealthy” to “hazardous” range. AC (which does ~the same thing for air quality as a purifier) or a purifier is pretty much mandatory.

[samstave]

When the fires were raging, I was looking at all the areas air quality from purple air monitors and some areas near folsom California were at ~700

And healthy is something like <100

[GekkePrutser]

Healthy is far lower than 100. 100 especially indoors is really bad.

[AlotOfReading]

Higher air pollution, especially during childhood, is also strongly linked to the development of asthma and other respiratory issues later in life. Pretty much everyone should at least be aware of their home air quality.

[hammock]

The benefits, yes. Those would be dependent on the local environment and if it’s causing you specific suffering. But that experience sold me on the functionality at least.

[Joeri]

We live in the city and always are struggling with allergies. The whole family is always coughing or sneezing. We bought a xiaomi air purifier like in the article last week, started using it in the bedrooms for a few hours in the evening, and the allergies cleared up overnight. The particulate sensor is mostly useless, a known problem with the xiaomi models, but running it at a fixed setting seems to clean the air quite effectively.

[andor]

The particulate sensor on my Xiaomi air purifier correlates really well with the numbers from my city's air quality network.

What doesn't work well for me is the auto mode, it barely does anything at less than 50µg/m^3, way too high even for the mediocre air in my area. So instead I use automation in their app to let it run at full speed for 30 or 60 minutes.

[5e92cb50239222b]

They use Chinese air quality standards, which are very high relative to most other countries for (probably) obvious reasons.

https://en.wikipedia.org/wiki/Ambient_air_quality_criteria

[legulere]

The soot they filter out of the air is very visible when you change the filters (they turn from shining white to grey). Air pollution is one of the world’s leading risk factors for death https://ourworldindata.org/air-pollution#air-pollution-is-on... . Though that varies a lot from country to country, it is a problem you can strongly reduce with throwing a tiny bit of money on it.

[gruez]

If the filter is only turning Greg it sounds like what you're seeing is dust rather than soot. I have a pm2.5 meter and over the winter/spring the reading is almost always 0 or low single digits, and my filters still turn grey

[dxhdr]

> Do they make a difference? Perhaps a placebo? A must have?

Purchase an air quality monitor, something like the Dylos DC1100. Then run a HEPA filter in a closed room for 30 minutes. It will remove almost all particulates! They work extremely well. Whether it "makes a difference" for your health is less clear.

[criddell]

Are the lower priced options on Amazon junk compared to the DC1100? I’d like to get a monitor, but I know I’ll probably only use it 10 times. The Dylos would end up being about $25 / reading…

[dxhdr]

Good question, I bought a Dylos back in 2015 and can't remember how the other options stacked up when I researched it. I've been happy with the purchase and would recommend it if you're interested in watching air quality. It has a convenient "monitor mode" where it will re-sample the air every hour so it's not constantly running. It's neat to see how the air quality in a room changes based on having the windows open or shut, after cooking, just being in the room, etc.

I'd expect there are smaller / sleeker / more advanced monitors out now though. Generally speaking I think you want a laser detector instead of the cheaper infrared detectors.

[criddell]

I found this link with test results:

https://www.aqmd.gov/aq-spec/evaluations/summary-pm

[MengerSponge]

If you live on a main road, there's likely a lot of pollution in the air. How much is actually in your home will depend on a lot of complicated things (prevailing winds, home construction, etc), so it's best and easiest to just measure.

HN's own https://news.ycombinator.com/user?id=ahaucnx has a company with a DIY version: https://news.ycombinator.com/item?id=27124671

I got a Dylos before I learned about AirGradient, and I really like it too. Depending on your budget and tech savviness, it's a great option too.

One important note: these detectors don't do chemistry, and not everything that causes a spike of PM is actually a problem. Showering, for example, will cause a spike for hours, but those salts are probably fine. Running the oven will also cause a spike, and those particles probably aren't fine.

[arinlen]

> Do they make a difference? Perhaps a placebo? A must have?

It really depends on where you're coming from.

I have one of those air purifiers from Ikea (Förnuftig). It's cheap but not the cheapest. On any high dust/polen concentration level day, a minute or so with the device turned on at full blast is enough to make any problem go away in that particular room.

[fragmede]

PM2.5 particles are considered harmful, ingest at your own peril. Some air filters will also include an air monitoring device, so you can just for yourself how many of those particles are present (partially burnt food is an extremely common source of these).

[jaqalopes]

Ancedotally they work 100%. Not only do they remove noticeable odors, they suck up tons of allergenic dust and invisible particulates that can mess with your breathing (if you have a sensitive respiratory system).

Non-anecdotally, I've heard it claimed that indoor air pollution is the #1 factor in reducing the lifespans of otherwise healthy people. No idea if this is the case or what the evidence is, but I don't find it hard to believe.

[Rastonbury]

In developing countries they have poor stoves at home which give of smoke/CO which is harmful aka indoor air pollution. A good easy way to prevents deaths/harm from these is to provide them with quality stoves. So depending on where you heard it, air pollution could mean these stoves which typical don't exist in the developed world

[legulere]

Frying things even on induction still easily drives particulate matter pollution to levels of bad days in China/India.

[Rebelgecko]

Even in developed countries, I think most homes still have gas stoves which are bad for indoor air quality.

[phphphphp]

I (in London) bought one recently (a COWAY Airmega) to try and improve the air quality in my apartment, specifically, the dust which has been reeking havoc on my breathing because of allergies.

There is a noticeable improvement but it has not solved the problem by any stretch: so while I don’t regret the purchase, and will keep using it, I am not how sure I’d recommend them for the someone without breathing difficulties / allergies etc.

[teaearlgraycold]

I got the same one and it’s amazing for California when the air is smokey.

[trompetenaccoun]

If you don't understand the purpose, it means you don't need it - as so often. The reason they exist is that in some parts of the world the air is so bad it literally has significant negative health effects just breathing it. That's why people use them, and for what it's worth as far as I understand the quality ones do work, in the sense that you can use an air quality meter and detect a noticeable improvement in air quality. They have filters that you need to change regularly.

-Edit- Since so many people are raving about them and recommending you buying an air purifier I want to add this: If you live in a place where the air is truly that bad, my main recommendation would be to move. I have personal experience with this, it's not worth it living like that. You may filter the air in your home but then whenever you go outside you're at risk, if you do sports even more so. Some people wear surgical or cheap cloth masks but these don't actually work.

Don't listen to people who tell you that you can "see" pollution of "feel" the difference. I've lived in some of the most polluted cities in the world and the truth is in most cases for regular healthy people they don't notice anything for years, even at pollution levels far beyond the imagination of folks in Western countries. Most of this is their imagination or placebo like you suspect. For example I've had people complain to me that the air is "so bad" in a place that's naturally foggy and where visibility is often low, but had good air quality. Others were happy about the lovely "clean" skys in a city that gets lots of sunshine but was actually horribly polluted. Also sure, smoke from wildfires is visible (and short lived) but a lot of the pollution from industrial sources isn't. It's a slow and stealthy killer.

[ms4720]

Depends on a few things:

1. what that particular filter filters out: ppm, mold, chemicals 2. What is in the air being filtered 3. How sensitive you are to the things in your air 4. How often the rooms air gets filtered through the filter 5. How effective the filter is

I worked in Beijing for a while and going somewhere with filtered air literally felt like a weight was removed some days.

[DragonStrength]

The biggest effect is in homes without any sort of central air system, which would usually include various levels of filters up to HEPA and UV systems at this point. During the worst of fire season in the Bay Area though, a single Coway HEPA filter, basically a box fan with a HEPA filter strapped to it, kept my apartment in the "safe" range for AQI. Just stepping out my apt front door into the hallway I'd be hit with the heavy stench of smoke.

Truly remarkable how well they work, but whether you need one or not depends on whether you have allergens/pollution as an issue in your home. You can purchase an air quality monitor (I have a Temtop M10) or check online measurements of AQI, pollen, etc. for your area. If you have an issue, they work, but not everyone has an issue.

[techwiz137]

Okay so I bought a cheap-ish Air Purifier, now because the brand is...I think it's Chinese(Rohnsonn), I can't determine if it really does anything, if these filters do anything at all to improve my air quality and if the UV light is even strong enough to kill germs. Is there a way to verify it's effectiveness?

[DragonStrength]

I'd look at what the purifier claims to eliminate and find a quality monitor that will give you a reading. Most are portable, so you can compare to outdoor values directly. You're going to need some baseline to compare to though. If you have an AQI in the safe range already in your home, you'd have to contrive some actual experiments or find someone who already has.

I'll say I'm pretty distrustful of anything but filters personally. My mom purchased a purifier at one point which claimed to use UV light to purify but had no fan to actually pull air through the light, so obviously, it wasn't doing anything.

[haunter]

My parents live in a very old house (~1700s) and it reduced the dust significantly. Not perfect but maybe it's on the model too. Like it's not an $1000 one which would probably work much better

[input_sh]

They're pretty much all the same, just a fan in front of a HEPA filter. If you can get a square fan and tape a HEPA filter in front of it you'd get pretty much the same result as many modern air purifiers.

You're paying for convenience and some bells and whistles (like a mobile app and an air quality reader), but the underlying technology behind it is pretty bare-bones, heavily tested, and heavily used in industrial applications.

[azuredragon]

They also double as a mosquito trap. I used to suffer persistent mosquito annoyance at night, but, since I got an air filter, the problem is gone. I often clean out dead mosquitos from the air filter

[throwaway290]

There is no level of pm2.5 that is considered safe to breathe, and it is easy to find out levels in your area so make your own call based on that.

It will be a placebo if your home cannot be isolated from outside air or if you don't make an effort to keep windows closed when air is bad.

Also, many expensive purifiers are overpriced junk compared to even simple DIY solutions like those found on particlecounting Tumblr and similar. Ideally the first thing to do is get some reputable air quality monitors.

[Mister_Snuggles]

One of my cats, who's since passed away, was asthmatic. Air purifiers throughout the house and a motion activated box fan plus furnace filter near the litterboxes resulted in an immediate and noticeable improvement in his quality of life. I've noticed a similar improvement in my own health.

I've since ended up with a variety of air cleaners:

* IKEA FÖRNUFTIG[0] is a small and relatively quiet unit. It can be wall-mounted, so it can take up virtually no space. The unit is reasonably priced. Filters are cheap.

* IKEA STARKVIND[1] is a much larger unit (also available in end table form[2] to save space), but also relatively quiet on the lower speeds. It's an interesting unit - integrates into Home Assistant (the unit speaks Zigbee), and has a PM2.5 air quality sensor. This unit is a lot more expensive than the FÖRNUFTIG, but the filters are reasonably priced.

* The box fan plus single furnace filter is incredibly noisy, but really good at dealing with cat litter dust. There is a huge range of price/quality when it comes to filters[, I just use the cheaper ones since I'm focusing on large dust particles.

* I have a couple of units that use Bionaire aer1 filters[3]. The units I have are quiet and reasonably sized, though they get louder as the filter fills up. The filters are expensive, and one of the units takes two of them which doesn't help matters. There is a variety of filters available.

There's a huge spectrum of tradeoffs between noise, size of the unit, filtration effectiveness, replacement filter cost, and extra features. I'm not convinced I've found the sweet spot yet.

[0] https://www.ikea.com/ca/en/p/foernuftig-air-purifier-white-5...

[1] https://www.ikea.com/ca/en/p/starkvind-air-purifier-black-40...

[2] https://www.ikea.com/ca/en/p/starkvind-table-with-air-purifi...

[3] https://www.bionairecanada.com/en_CA/service-and-support/aer...

[radicality]

I recently got a Medify Air MA 125 after a lot of research. Can recommend the brand.

And yes it definitely makes a difference. Sometimes when I open my windows to get some “fresh” air and remove the co2 from my room, the ppm momentarily goes up. Also very useful for cooking since I don’t have a great vent. Ocassionaly when frying something ppm goes over 200 but it quickly drops down with the air filter.

[KennyBlanken]

If you have central air heating/AC and a vacuum cleaner that has a hepa bag, you likely don't need one; just buy filters that aren't the blue spiderweb kind and vacuum regularly.

[dzhiurgis]

HRV frequently has filters too

[herbst]

If you smoke indoors it's a must have I would say. It's a difference between day and night.