Smart Air联合创始人Anna在北京朝阳门15平米卧室测试了全新的小米2 (Mi2)机器。这个卧室是我们以前测试DIY、IQ Air, Blue Air和飞利浦的房间。Anna分别做了6次自动档测试,和6次最高档测试(小米把最高档叫做“最爱档”)。






为了算效果,Anna用了一台Dylos Pro激光空气测试仪。这个Dylos测到≥0.5 微米和≥2.5微米颗粒。我做了对比测试发现,  Dylos 0.5微米数据跟美国大使馆PM2.5相关性很高r = .90)。


和我之前做的测试一样, 为了算效果,我算了(卧室里开机前的颗粒数)比 (测试最后四个小时的颗粒平均数)。





Xiaomi effectiveness





下面是比较正常的测试,我还加上了世界卫生组织的PM2.5 24小时上限(25微克)











xiaomi 杂音



杂音VSPM 2.5











净化器开机至少一个小时的时候,同时外面的空气不安全(PM2.5 > 25微克),有多少小时室内空气也不安全(> 25微克)?





也许小米使用的是中国官方的PM2.5 24小时上限(35微克)。即使如此,在小米启动77%的时间里,室内的空气污染 指数还是是属于不安全的。



得到这个结论我想特别小心。我看到过其他人测试小米第一个版本,然后结果不错,包括美国医生Dr. Saint Cyr的测试。(不过,我也看到报告说小米的机器有问题,比如这个人,滤网还在塑料包装里,让小米开最高档,app还说污染立刻下降。)所以第二次第三次分析了数据(所有的数据也是公开的):


  1. 我们用了别的空气测试仪在别的房间做测试。
  1. 我开除了外面AQI有任何比较大的波动的测试天。
  1. 我分析了外面AQI中度或以下的测试天(< 150微克)。
  1. 我比较了这次测试和我最近在这个房间做的测试。
















Leave a Reply

44 Comment threads
60 Thread replies
Most reacted comment
Hottest comment thread
60 Comment authors
newest oldest most voted
Notify of

So which air cleaner out there has a functioning auto mode?

Right now, none that we’ve tested. We wrote a follow up article to this one explaining why a purifier’s auto mode isn’t reliable. In recent years sole purifiers have been released that case work with standalone particle counters. These might be more reliable, but we don’t have any data on it yet.


So it’s either run full time with all the noise, or buy a separate particle monitor and manually turn it on and off?

My problem is that I can clean the air in the room, and then the air conditioner/heater just pulls in more dirty air from outside. What we really need is a filter in the AC vent. Anything like this out there?

We’ve tested some of the 3M filter paper you can put over air conditioners. We’ve found it works fairly well (but it’s no replacement for an air purifier). You could look into getting that.

Having said that, we’ve tested whether Aircon actually brings in dirty air and it doesn’t. Although it sounds like you have a central air system which could well be bringing in dirty air


Huh, really? I thought it pulled in dirty air from outside. It doesn’t? Well that’s good… Read more »

Here’s a link to the 3M AC filter we’ve tested, although the page is only in Chinese. If you search for ‘3M Air Conditioning filter’ you should be able to find some more results!

Your observations of the Xiaomi sensor seems to be in line with what we found. We wrote up a separate article on how well the Xiaomi’s sensor performs


That writeup is for the sensor for the Xiaomi 2. This is the Xiaomi 2S, which has a different sensor.


Thanks for the link, I bought the filter paper.

The Xiaomi 2S appears to be doing okay. You can’t use the auto mode as the onboard sensor records values much too low and the auto mode’s thresholds are too high. What you can do is go to ‘automation’ and set your own thresholds. I set it to go to ‘favorites’ i.e. high when PM25 reaches 10, and turn back to ‘auto’ at 3. This appears to work.

Fe Ev

Does the automation work with an iphone or only android?

Fe Ev

Does this trick work? At what speed do you have it turn on when pm2.5 gets to 10? And it stays at that speed or goes into auto?


Hi Thomas, It was a really thorough and detail test. It’s really insightful. I couldn’t … Read more »

Hi Ray, great feedback and thoughts! We have tested the 2S built in particle counter, you can read about the Xiaomi Mi 2 air quality monitor tests we did here. What we haven’t tested is the Mi 2S particle counter. We want to get round to testing that soon, so stay tuned!


the model 2 Has poor particle measure sensor. Could you please test again with xiaomi pm2.5 Air detector and use this detector to control the mi air purifier 2 In automatiom mode. Is it will be better or not?


It is not designed to run at full power mode all the time. It will break your machine. The actual problem is that it has insufficient air cleaning power for your environment. You should make your room more air-tight by adding rubber seals on your windows and doors.

My room is 30m^3 in Bangkok. And it is more than sufficient for me. The PM2.5 value always below 10 μg/m^3. Sometimes it is even as low as 1 μg/m^3.


Hi all. I currently have a Cannon, a DIY , a Xiaomi 2S , and I just got a Xiaomi Pro. I never had an… Read more »


Only the 2S does not switch back to auto. The PRO always switches back to auto. Don’t get the PRO, get the 2S.


I just bought a pro. No issues with it switching back to auto mode, maybe they’ve fixed this i… Read more »


Xiaomi air purifier works well at a low cost. The new ones 2S and Pro do not have issue with automat… Read more »

Great writeup Joe, you’ve hit a lot of the main points! The biggest concerns we (Smart Air) ha… Read more »


Hi guys,

Does anyone have information if Xiaomi have plans to change the Chinese standard for clean air to European standard? Changing the location to Europe in the Mi Home app did not affect the criteria when the fan speed should be increased. I am aware that I can automate the process by setting “Switch to My Favorite mode” when the PM2.5 quantity is >25mg/m3 but I was wondering if this is going to be somehow automated by the purifier itself.

Paul The Rock

Maybe not until these units will be officially sold in Europe… Now they are sold only in China, so they are settled to their standard…


what blue air models were used in these tests?

Hi Dale, good question! The Blue Air we used in our tests was the Blue Air 203/270E. You can find more details specific to the efficiency tests we did on the Blue Air and the other models in this post.

Vladimir Angelov

Can I turn off the wifi somehow?

Not that I know of, I think the WiFi on the Xiaomi is programmed ‘on’. In fact, it’s impossible to control the purifier fully without the WiFi turned on and the app installed. Without WiFi you’d only be able to toggle between the three modes: ‘favorite mode’, ‘auto mode’ and ‘sleep mode’.


After testing the mi2 purifiers (2 of them) this is the conclusion.
The device will work all night long as long as you set the speed no higher than (22).
If you increase speed above 22, then the 3 hour cut off kicks in, but 22 or lower seems to be working all night.
You can test it out and share the results.
also this is running on the current firmware, maybe that makes a difference.


What about decibel levels, can one sleep on 22 speed setting?