家里空气有毒害？你的小米测试仪觉得没问题！

《家里空气有毒害？你的小米测试仪觉得没问题！》有68条评论

1. I just came to comment that several years on Xiaomi still has the same problem.

   Yesterday I bought a Xiaomi Mi Smart Air Purifier 4 Compact. I’ve found it happily sits there saying everything is green while my Laser Egg was showing US AQI of 120!

   This means the Xiaomi auto setting always stays in silent mode. I’ll have to see how bad the AQ has to get before it decides to increase the fan.

   Fortunately if I set it to manual high speed mode it reduces the AQI very well, but the auto setting is useless due to the inaccurate sensor.

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   • Thanks for the update, Ed! It’s a shame this still hasn’t been fixed even with the latest Xiaomi 4 Compact purifier. I hope Xiaomi can do something to update the firmware and fix this.

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2. I recently bought a Mi Air Purifier 3C. I think your conclusion is off the mark. As long as the purifier is running on auto, (low speed) the air coming through the filter is clean. I have an air quality detector that tells me the air quality is clean. Lighting a cigarette makes the Xiaomi meter go above 200 and the fan speed goes up also. My stand alone air quality meter goes way up also. Within about 15 minutes it drops down to 7 and often lower. Based on that, I trust the air purifier laser detector. I also have two Hatari Hepa purifiers and those readings are similar. Neither Hatari has meters. The filters in all three purifiers are only a week old or so.

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3. Hi everyone,

   I am new to the air purifiers’ world and buy a Xiaomi 2H recently because my wife has dust allergies. The air quality issues seemed very complicated and I am very happy that I encountered this blog!

   I have a different issue with my device: The particle counter in the app seems inaccurate, it even makes me think that the numbers are random. For example, it shows 10 and when I restart the app, it goes to 32. After running a while, I check again and it becomes 35!

   Have you encountered any similar situation?

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4. I have one first gen and two second gen Xiaomi filters. As they had crappy sensors, I switched them for laser sensors modules from Taobao and it improved… at least I had the same range of reading as my independant DIY sensors.

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   • Very interesting, can you share with us how you did it? I think there will be plenty of people interested in this improvement!

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5. I’ve just bought an Xiaomi Air Purifier Pro (Europe) and it read 004 and in about 1h got to 001. The reading was correct as the exterior calculation (an independent website that calculates air quality in my area) showed 005.

   Of course it is low now because of the lockdown, but usually is about 100+.

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6. I think is, except for the counter, a defect of quality of the filter bought. There are different series of filters that you can find on-line, did you tested some different filters?

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   • Hi Cristian, there is an in-article link linking to another test on Xiaomi. The filters are okay as long as the fan runs on the proper speed. https://smartairfilters.com/en/blog/xiaomi-auto-mode-leaves-air-unsafe-86-hours/

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7. I am really surprised as I was led to believe the Xiaomi purifiers have a high quality laser sensor! I can’t find any info about the sensor in my Winix 9500 or whether it’s accurate at all, and can not decide which purifier to buy to replace the one in the lounge as filters for that are no longer available. Do you know if the Dyson is any good?

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8. Hello everybody,
   I also found it strange that the readings seemed inaccurate and my filter does not go below 25 (only one or two out of every month or so – i didn’t find a corelation between that and the outside weather).
   The OLED display on the filter does not say if it is measuring PM or AQI. Only the mobile app says PM. But digging a little further makes me believe that it shows AQI instead of PM. The clue that led me to this conclusion is that up to around 50 the display is green (so the air is excellent to safe) and above that is worse. If you look at the AQI index it says that up to 50 the air is good. Otherwise all the numbers don’t add up, just like in your measurements. Did you find similarities in AQI values between the filter and the sensors? (ignoring the PM values).

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9. But Xiaomi has an option for manual mode so particil counter will not control the machine.

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   • Hi SKN, you are right! That what we recommend in the article. If you are a Xiaomi user, use the manual control instead of the auto mode!

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     • except manual mode shuts off after 3 hrs

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10. Any updated test with the xiaomi air purifier 3 to see if the sensor has changed?

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    • Hi Lai, we haven’t got a chance to do the test on the new model yet. But good thought, we will test it out when we have a chance to do it!

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11. I just bought the version “3H” model in Bangkok, with all the improvements including HEPA filter a week ago and have been testing it out.

    It stays at the fan setting you set it to indefinitely (does not revert to Auto mode). It has an attractive OLED display right on the device and I didn’t even bother to use the app. The displayed value seems pretty random and seems to fluctuate between 1 and 8.

    I figure, at the end of the day it’s a box with a fan and a filter. Might as well filter out all the particulates possible, as I’d rather buy a new filter whenever necessary than breathe them in. So, I set it to the highest fan setting I can stand the noise of. For me that is 1 bar (barely audible) or 2 bars (like a spirited bathroom fan). 3 bars is unbearably loud, halfway to vacuum cleaner. If the air outside is bad I’ll dial it up to 2, if the air is nice and I want some quiet I’ll put it at 1.

    The nice thing about this one is that the industrial design and construction quality are gorgeous. There are probably better machines out there but this one is popular so there’s little worry about obtaining replacement cartridges.

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12. Can we have an Air Purifier and a Humidifier in the same room? Will a humidifier affect the functioning of HEPA filer ?

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    • A humidifier shouldn’t affect the effectiveness of your HEPA filter. We’ve run tests, and HEPA filters don’t affect humidity so there should be nothing to worry about running a humidifier and air purifier in the same room. However, humidifiers and humidity can affect some air quality monitors, so if you have an air quality monitor (or if you’re using the one built into to the Xiaomi), it’s worth being aware of that.

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13. I think there are no worse product reviews jn the Internet than reviews about air cleaners and if you complain the review, than they will just not post it.

    The MI air cleaner has only an H11 HEPA filter and all those problems you mentioned but everywhere they hype him to number 1. They write buying guides and then recommend MI XXX as the number one air cleaner jn the world.

    Some pages just look at the CADR rating but ignore that you have to concentrate on the smallest particles and for that the CADR is useless. Air cleaners with bad H11 HEPA filters get better CADR values than air cleaners with good H14 HEPA filters because air flows better through bad filters and for big particles the H11 also has good retention rates.

    The result of all those poor reviews is that companies produce bad air cleaner that just sound good on paper and the people who write all those reviews are easy to impress with those marketing numbers.

    A good example are the dyson air cleaners. You have to read a lot through the marketing material to understand that only around 5 % of the mentioned air in the airflow is actually cleaned! The video below explains their air multiplier technology. 95 % of the air comes from “outside” and never passes the air filter! If you ask them directly about this they talk around it and just mention the airflow. Try it and ask them 🙂

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14. this is such a shock to know about Xiaomi air purifier since I heard that Xiaomi air purifier is such a big hit and sells a lot!

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15. What about the Xiaomi MIJIA Air Quality Detector?

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    • We’re yet to test this air quality monitor, but hope to get round to it in an update to this study. We’ll post an article in this Knowledge Base once it’s done!

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      • Thank you!

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      • Yes please! I just bought a smartmi pm2.5 detector and find that the readings were way below my country’s API reading. Its the small rectangular model with display for only 2.5. Id be grateful if you could test that out. Doesnt cost much too.

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      • Any update on this? I am interested to see the results.

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16. Mine goes down to 1 on heavy rain days when outside air pollution is really low. Usually, it’s around 9/14. I’m in Guangzhou’s downtown, which is way less polluted than Beijing

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    • We’ve found that humidity can seriously affect the accuracy of air quality monitors. In fact, we had one Smart Air fan run some tests in Guangzhou with the Laser Egg so we could compare it to Beijing. Here’s our article on on how humidity affects air quality monitors

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17. Hi all,

    I am just discovering these analysis, wow, I am impressed.

    Do you think there is a way to calibrate a Xiaomi Air Purifier ?

    I just received a Xiaomi Air Purifier Pro EU version, and since I started it, it shows 001. I have a netatmo sensor (weather station) which indicates 657 ppm in the same living room.

    OK, I live in Paris suburbs in France, it’s quite windy today, my window is opened, but I can’t believe the air is so clean in my apartment.

    What do you think ?

    Thank you very much.

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    • Same for me. When I started it it was around 10 ppm, now we had a rainy days and now it sits at 1-3 ppm. So in auto-mode it is not filtering at all. Only way is to set it manually, I usually do this before sleep so air in the room is clean.

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    • What was the trading at the very start? Should be same / similar to outside

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    • did you test the new Xiaomi Air Purifier 3 with laser sensor? It should be more accurate

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      • We’re in the process of testing, Tony! We hope to have an analysis out soon.

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        • Looking forward to your analysis. Just got the Mi 3H and am wondering how accurate it really is.

18. I got the Mi Air 2s. It sits at 1 microgram when I got it. Stayed there most of the day and I thought it was busy. I did wave something dusty near the sensor and got up to 5. When cooking in an open plan area, filter in lounge, I get a 2. Suspect something wrong here? As you say useless in auto mode. Lucky I have a schedule which can control it to the doped and times I select. Unfortunately there only one speed for user/manual mode.
    Otherwise it’s great.

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    • You can fix it higher by using tje Xiaomi Mi Home app, join your purifier to the network, add the purifier, then select, say 60% power, on favourite mode, then use automation to add a rule to say

      when (null), run Favourite always on

      Then whenever you select Favourite, it will stay there at 60% forever

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19. I have the pro and it goes down to as low as 3. I live in Saigon and when I first used it it registered 39 in my apartment which is in the central area and this correlated reasonably well with the AQI reading outside pretty well. I think you guys get too caught up on the numbers. It’s cleaning the air and a positive benefit than not. For around 200usd. If you were paying 5 times that, I could probably understand the complaining.

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    • If the device is “cleaning the air” then it would have accurate and reliable numbers on a test. From the test above, that is not the case. Arguing against data is a losing proposition.

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20. My 2S is showing 006 (or 005) at startup. Then it does not change whatever the conditions are.
    It’s brand new. What should I do ???

    In parallel I have bought a cheap (but very efficient) Breathe Fresh + MI Air Quality detector + Xiaomi Smart plug = should be a good alternative 🙂

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21. I got my device on December 2018 and by default the custom mode works at maximum speed and does not switch to automatic after 3 hours. It showed 47 when I put it outside (correct number was 170). Inside I’ve seen it go as low as 5.

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    • What device do you have? 2? 2S? PRO?

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      • Hey Danny, I also have 2S and it never switches to auto mode. Manual mode is very loud though. One more issue which I noticed, and you never mentioned, temperature readings are way off, I don’t have any other device to compare humidity readings.

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        • Manual? Or favourite?

          Install Xiaomi Mi Home app. Adjust favourite to level you like.

    • I wonder how yours did not switch. Mine did it earlier. So I added an automation rule. Stays at whatever % I choose forever ??

      Chinese model. June 2019

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22. Hi Thomas,
    Thank you for this very useful information!
    Do you know if any similar tests have been done with the Mi Air Purifier 2S? Very curious to any test results of the Xiaomi Mi Air Purifier 2S.
    https://www.mi.com/in/air2s/

    Thank you in advance,
    Ala

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23. Moin Moin,

    thank you very much Thomas for your interesting and well written articles. I share the same observations with my Mi2 purifiers but comparing the Mi2 Pro to my laser egg and Xioami particle counter, the results fit much better and also the MI Pro goes down to 1.

    A tip for all Mi purifier users: I only use my purifiers in manual mode! How does it work? You just have to program under automation: If the PM2.5 concentrations is below 500 (which means always), switch to manual mode. This is how you can prevent them to switch to auto mode after some hours automatically!

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24. Hello,
    just read the article out of curiosity, and well some points are somehow weird. I belive the sensor is quite accurate, if they build in what they claim to use. Purely from the technical PoV.
    But going by your data it is more likely, that the software used is wrongly programmed. They write to use shinyei sensors, which do not give an output in any unit but in an voltage equivalent between around 0.5 and 5V. So going by this, the Data you get is most likely the output Voltage of the sensor. Most likely the developer for the purifier took that output directly and fed it to the software as input.
    And herein lies the problem, going by your data he most likely used the wrong stepping for the adc in the control unit, which resultet in a voltage output in far too high steps.
    Well to say it in an easy way, the got a dounce to programm the software and set the electronics, and in the pro version they most likely simply used a sensor which gives digital output and therefore does not have that problem.

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    • Rolf, you’re right that the software-side of particle sensors is often the most important, since there are so many variables at play especially when you’re converting from a particle count (which the sensor gives) to a concentration or AQI (which is what we’re most often used to). In some of the more accurate air quality monitors we tested, they all use fine-tuned software to adjust for different variables.

      Having said that, there are other issues with the sensor in the Xiaomi, firstly that it’s located right next to the purifier. This means you’re only getting an indication of the air around the purifier, as opposed to on the other side of the room. This can be dangerous if you’re using the Xioami in auto-mode, where the sensor is reading clean air (near the machine) but the truth is the air on the other side of the room is not clean.

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    • The Pro sensor is different to the smaller 2s?

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25. Xiaomi also offers a standard alone monitor. Will this essentially be the same tech as found within the air purifiers? If so I’m worried about wasting my money.

    I’m debating whether to buy the xiaomi air monitor or the laser egg. The reason I’d prefer the xiaomi is because I already have a fair amount of stuff in my house from them! It’ll all be the same smart system, rather than using yet another APP for the laser egg.

    Does anyone have any ideas?

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    • Good question Chris. We’re yet to actually test the standalone Xiaomi Air monitor (although it’s something we want to do soon!). Ultimately the sensors in these devices are all the same (they cost around $5-$10 per sensor) but what’s different between each monitor is the calibration and testing of the devices. I know this is something Laser Egg have worked on a lot (see the article we wrote about how humidity affects the Laser Egg), but I’d be less sure about the Xiaomi (since they’re a company that puts out 101 different devices). Having said that, I have no doubt it’ll be ‘reasonably’ accurate, but accurate enough to ensure your air is clean 100% of the time… that’s a difficult one to answer.

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26. I can confirm that the air purifier 2 never shows less than 9. As for the issue with the AP2 going back to auto after 3 hours it should be possible to circumvent this using the app’s automation options. E.g. set it to change modes at certain times. Not an ideal solution for sure, but should work. I just got the Xiaomi laser pm2.5 sensor and it generally shows far lower values than the AP2 built-in sensor. The sensor is linked to the AP2, but unfortunately the automation options that deal with pm2.5 concentration don’t seem to work very well. When I set a rule that the AP2 should turn on when PM2.5 levels exceeded 15, the rule wasn’t triggered when it reached eg 17. However when I set the limit to 35 and i sprayed some shoe impregnation spray near it or burned some paper it worked without issue. It seems it has problems with the smaller numbers or something.

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    • Right on–our tests found that the Xiaomi particle counter had problems both in low AQI range and the high AQI range. My guess is similar to yours–for some reason, they seem to have programmed it not to go below a specific number.

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      • My Xiaomi Air Purifier 2 Pro has shown as low as 3 ppm.

        June 2019 Chinese model. Kuala Lumpur purchased.

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    • I have an AP2 Pro, and my purifier can display down to 1mg/m3.

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27. Hi!

    You can easily find on the internet, that versions “Pro” and “2s” have new laser particle sensor. I’d hope it is far more accurate than the old sensor in the version 2. Would be great if you could test it somehow…

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    • I own Xiaomi Purifier 2S with PM 2.5 display, it’s showing really low values most of the time (like 007) and it’s quirky, reading from low to high in short intervals while nothing changed indoors. It’s showing 001 last couple of days… seems like malfunction after 3 months.

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      • My story is similar to as MATIJA’s. Received Xiaomi Air Purifier 2s few days ago. It shows 001 almost all the time. However, when smoke is around or spraying something near it – it goes to 70-200-600. Then in few minutes goes back to 001. Looks like working, but don’t understand how my indoor air could be so clean, just don’t believe it.

        Any solutions or comments appreciated.

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        • Hello Rodion,
          I just received a Pro version, and since I started it, it shows 001.
          I live in Paris suburbs, it’s windy today, my window is opened, but I can’t believe the air is so clean in my apartment.
          Have you find a explanation ?
          Thank you very much.

28. Did you really test the Mi2 Pro with it’s much more accurate laser particle counter? I have doubts.

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    • Hi Max! I tested the Mi1, Mi2, and Mi2 Pro. Unfortunately I only have a record of the Mi1 and Mi2 data. The Mi2 Pro was at a friend’s apartment, where I had access for a limited period of time. The pattern of the data on the Pro versus the Dylos and the Laser Egg was the same as the Mi1 and Mi2–when air was bad, the Mi2 Pro was vastly undercounting. When air was very good, it was overcounting.

      Does Xiaomi claim that the Mi2 Pro has a better particle counter? I’ve searched their website and haven’t found any claim about the particle counter. If you find a specific claim, let me know. Also, if you have a particle counter and the Mi2 Pro, let’s set up another test!

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      • TL;DR: Particle counter in Xiaomi Air Purifier Pro is accurate (tested for 33µg/m³ and 93µg/m³ of PM2.5 particles) and it goes down to 1 when air is clean. It starts to work faster definitely sooner than 70.

        I was worried after reading your articles, because I have just bought Xiaomi Air Purifier Pro. That’s why I did some tests of the particle counter myself. Most of the days were windy, so outside it was ~15µg PM2.5, inside like ~6, so I couldn’t do the test. (Poland suburbs)

        One day it was 33µg outside ( https://airly.eu/map/pl/#52.37507,20.92708,i2833 – there are two very close to my flat) and inside Xiaomi showed around 10µg. I have plugged it on my terrace (floor 0), and it was showing values very close to 33, going down and up +- 10 at moments. Cool, I thought – but it wasn’t enough.

        Today, airly sensors outside showed 93µg of PM2.5, and Xiaomi showed 20-30 inside. I have immediately put it on my balcony – it showed values very very close to 93, very fast. It varied from moment to moment (wind also varied), but in general it was showing a measurement very close to what airly sensors showed.

        When I have closed vents on my windows, the air went better, when I had them open – the contamination went up on Xiaomi.

        The auto program makes it work faster definitely sooner than 70µg – I have checked that by making some smoke from putting out candles.

        Maybe it’s all because of the newest “pro” version, or maybe it varies from model to model. I’m very happy mine works fine. 🙂

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      • Yes please re new test!

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29. I love your data and hard work. I curious though: 1. How does the Xiaomi standalone particle counter stack up?
    2. How does the mi2 performance rate if left at medium, hi, or even turbo?

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30. I tested in my home two Xiaomi Air purifiers (2nd generation), and the stand-alone Xiaomi PM2.5 meter.

    The stand-alone meter is using laser technology, just like any other decent PM2.5 meter on the market. Yet, Xiaomi refuses to answer what technology lies behind the integrated sensor within the Air purifier (1st or 2nd generation). It is interesting to note, that on its 3rd generation of the air purifiers, Xiaomi ditched the old sensor technology, and switched to laser technology too (same technology as in the stand alone meter).

    From my experience, the stand-alone PM2.5 meter from Xiaomi seems to be accurate (when comparing to government PM2.5 meters in my area). Regarding the integrated meters inside the two Xiaomi air purifiers (2nd generation) that I’ve tested, one was constantly ~40 ppm higher than the stand alone meter, and the other seemed to be more in correlation with the stand alone.

    In any case, anyone who uses the Xiaomi air purifiers (2nd generation), simply purchase the stand alone meter if you want accurate control.

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    • Hi, I recently bought a Mi Air 2 purifier and was interested in buying the separate pm2.5 monitor, but so far I’ve found virtually no info on how much control and automation you can program the purifier via the data from the monitor. Can you tell me what is achievable with the two devices working together? I’ve already got a Laser Egg 2, but that has no way of controlling the speed of the Xiaomi purifier.

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      • Hi Simon! As far as I know, the Xiaomi can’t communicate with the Laser Egg.

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      • I’d like to know the answer too. Also, my Xiaomi Air Purifier 2 Pro doeS show over 50 and less than 9 ppm regularly. I wonder if the firmware was updated.

        However, outdoors, when I suspect it was around 180 to 220ppm (Kuala Lumpur in September ?), it only showed 80. But did light up red. I don’t have a separate monitor to calibrate it with. Air quality Friends around Kuala Lumpur were reading 180+ though.

        Any thoughts on this?

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