How Accurate Are Common Particle Counters?

When I started Smart Air in 2013, I wanted to buy an air quality monitor. I had basically two options. I could buy a US$260 Dylos or spend thousands of dollars on the crazy expensive particle counters. Since then, the market has exploded with new air quality monitors as cheap as 99 RMB. But are they any good?

Putting Pollution Monitors to the Test

To get to the bottom of it, Smart Air tested three popular pollution monitors on the market: the Dylos DC1700, the Kaiterra Laser Egg, and the Node.


Dylos DC1100 particle counter
Dylos DC1100

The Dylos is the trusty particle counter Smart Air has been using since 2013. We’ve used it to perform purifier comparison tests, and air quality tests in places like China and India.

Laser Egg

Origins Laser Egg air quality monitor
Origins Laser Egg

The Laser Egg from Kaiterra (formerly Origins) is a popular, more technologically savvy device.

AirVisual Pro

Air Visual Node air quality monitor
Air Visual Pro

The AirVisual Pro (formerly the AirVisual Node) is a fancier version, including a large screen, pollution forecasts, and even a CO2 monitor.

Comparison of air quality monitors

The Government Comparison

We placed the machines outside the Smart Air office in Beijing, on Dongzhimen Waidajie. That’s about 1.3km away from the government PM2.5 monitor at the Agricultural Exhibition Center.

Map of Smart Air Office and Agricultural Exhibition Centre

We ran the machines for six days. The Laser Egg and the AirVisual Pro give output in PM2.5 micrograms, and the Dylos gives number of 0.5 micron particles. As a result we converted it to PM2.5 micrograms using the semi-official formula (0.5 microns – 2.5 microns)/100.

Here are the results for the first (72-hour) test outside our office in Beijing:

test data for air quality pollution monitors in Beijing

Low-Concentration Test

Next we tested days with extraordinarily low PM2.5, over a period of 48 hours. That’s helpful because concentrations in homes—where most people use pollution monitors—are also typically low. We know this from tests we’ve done on air quality in Beijing and Shanghai. So with this data we should be able to test how good the devices are at measuring low concentration levels.

Low concentration tests for air quality monitors
Low-concentration tests

Eyeballing both graphs, all three machines did a pretty good job of tracking the official numbers. Combining both tests, we found that both the AirVisual Pro and the Laser Egg correlated r = 0.98 with the official PM2.5 numbers.


For non-nerds, 0.98 is incredibly close to identical! The Dylos had the lowest correlation at r = 0.90, but still incredibly high (and similar to our previous test).


These correlations are all extremely high, suggesting that they’re all tracking government data well.

Average Deviation

Another way to measure accuracy is to look at on average how far the numbers were from the government data. The AirVisual was the closest: it was off from the official numbers by an average of 4.8µg/m3. The Laser Egg was consistently further than the government machine, with an average deviation of 6.5µg/m3. The Dylos was off by an average of 9.1µg/m3.

Next we looked at deviation in the low range. The Laser Egg had higher deviation in the lower range. However, even these deviations were not large.

Low concentration PM2.5 deviation from Agricultural Center

The Airpocalypse Test

To test accuracy at extremely high concentrations, we burned a cigarette in a closed 15m3 room. Our goal was to see how well the particle counters were at reading concentration levels over a whole range of values, including toxic levels. With the help of cigarettes and a partner NGO in Beijing, we managed to get the concentration above 1,000µg/m3!

Airpocalypse test setup

For this test we also had another machine (Sibata LD-6S) on hand as a reference. This is an industrial PM2.5 dust indicator, with an accuracy of ±10% and repeatability error of ±2%. The LD-6S was used as our baseline monitor.

Airpocalypse test results
Airpocalypse test results

It’s clear from the data the Laser Egg and the Dylos had a hard time measuring high levels of concentration. In contrast, the AirVisual and the LD-6S matched very closely. Both were able to measure concentrations over 1,000µg/m3. The chances you’ll need to measure concentrations this high outside of experiments are slim, but the AirVisual did surprisingly well.

Take-Home Message

Overall, the three particle counters were reasonably accurate compared to the government machines. They’re all suitable for giving an approximate indoor air pollution (AQI) reading  in your home. Of all three, the AirVisual scored the highest. It had the lowest deviation from the government machines, and the highest accuracy in the “crazy bad” test.


Since all three machines are reasonably accurate, the question then really comes down to: How easy it is to use the device? And what features do they have?

The Dylos (1800 RMB)

The Dylos easily loses this fight. It has no phone connectivity, and downloading the data is a terrible pain—and that’s if you have one of the old school pin connecter cables. With new, much cheaper particle counters now on the market, the price is also far too high for what you get.

The Laser Egg (499RMB)

The Laser Egg is an entry-point pollution monitor. It gives reasonably accurate results with a simple interface. It’s not feature rich, but it does what it says on the box. The Laser Egg is a great low cost way of testing the air in your home–ideal for making sure your purifier is doing the trick.

The AirVisual Pro (Node) (1,480RMB)

To our eyes, the airVisual offers the best features. For starters, it can measure CO2, temperature, and humidity. That makes it more of an ‘environment monitor’ than just a particle monitor. If you have indoor sources of air pollution (VOCs) like new furniture or remodeling, high CO2 levels can mean that those indoor pollutants are building up. However, at 1,480RMB (over $200) it’s not cheap.

Conclusion: Which air quality monitor is top?

After passing our tests, we will start shipping the Laser Egg air quality monitor and the AirVisual Pro through our stores in China, India, and Mongolia. They’re both great options for anybody wanting a solid device for both home use and research (if you’re a nerd like us). Go take a look!

Over the next few months, we hope to get a larger pool of air quality monitors together and run more extensive tests. This is only the beginning! Once we’ve independently verified more devices, we may well be adding them to our shop as well.

UPDATE: The QP Air Quality Monitors

Since publishing this article, Smart Air has tested a new set of air quality monitors: The QP Lite and QP Pro. After testing out the monitors, we were impressed with their accuracy and functionality. We have replaced the Laser Egg on our Clean Air Shop, with the QP monitors.

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32 thoughts on “How Accurate Are Common Particle Counters?”

  1. Hello,

    Thank you for this review. I am curious if you have any recommendations for outdoor sensors that can be used to monitor pollutants, especially PM2.5, outdoors?

  2. Hi Paddy, great tests and information. Do you have any data on the internal sensors these devices use if we were to try and build our own IoT device? I’ve seen the OPC-N3 mentioned a few times, buit I’m far from an expert in this. We’re looking to build a low-cost sensor array across multiple locations.

    • Hey Gavin, glad the blog post was useful! I haven’t had time to open up these devices to check out the sensors, so can’t give any advice. What I do know is that most of them use the same sensor, which costs around $5, and they then all use custom software to calibrate and smooth the data.

      Good luck with your project!

  3. Please also have the air monitors available for sale in the Philippines. With the volcano erupting all the time people want more than just a visual check on whether there is ash in the air.

    • We’ll try to work on this Charm. We want to help protect Philippines’ air breathers! Can you give a list of the air quality monitors you think we should test, or a list of the most popular siir quality monitors in the Philippines?

  4. Thank you for this very very useful website. I am currently researching to find the best air quality monitor. The Laser Egg and the Airvisual are leading the race so far. Have you heard of Huma-i and Air Mentor? I would love to see some test results about them as well.
    P.S. Why on earth is the Laser Egg twice the price in Europe?! It‘s almost as expensive as the Airvisual.

    • We’ve not heard of the Air Mentor or Huma-i Anca! There are an increasing number of monitors on the market, which is great. Just before purchasing try and find data-backed information on how accurate they are, so you can make the most informed choice as possible.

  5. Hi. Have you tested these outside? I have the DC1700 & AirVisual Pro at my workplace, both claimed to work outdoor as well. We are doing continuous outdoor air monitoring at my workplace.

    • Hi Adi, the first graphs and test data comparing the three particle counters are all done in outdoor air conditions. You can use those as a reference for how well these monitors work in outdoor conditions!

  6. New test coming soon? Awair (second), Air Ae Steward, IGERESS, Foobot etc etc. I would even pay more for a good product but there are almost no labor test to find. So many products and no tests.

        • Great! I’ve just looked through the info. It’s very difficult to know how accurate/well the device will work without testing it, but one thing I’ve had experience with is using air quality monitors on a daily basis. I feel that having a screen (on the AirVisual Pro) is very helpful in reminding you as you walk out the door/head to the bathroom that your air is not good. I’d be worried that having to open an app to view your air quality would mean you’d get round to doing it less (unless of course there’s a notification that appears on your phone showing you the air quality). Other than that, the extra VOC sensor in the uHoo doesn’t necessarily mean it’s better. We’ve shown that VOC monitors can often be unreliable. Good luck!

  7. Hi everyone. My daughter and I were so happy to meet everyone when we picked up our DIY a couple months back and now we are also the proud owners of a canon as well.

    I was wondering if you plan to review the new Laser Egg 2 upgrade with the VOC sensor. I really want to grab a laser egg but if the upgrade works reasonably well, I’d prefer to have that one. Unfortunately, I can’t find anyone who has put it through its paces yet.

    • Hi Toby, really glad the DIY and Cannon are serving you well! Regarding the Laser Egg 2 with VOC tester – we have tested it here at the Smart Air lab, but have not written up the report. Our findings were that the VOC sensor can be overly sensitive and may not be the best indicator for VOCs. VOC sensors are complicated and there’s no ‘one size fits all’ for VOC devices. Our advice in the meantime is that if you do buy a VOC detector, be sure to read up about the numbers and what they really mean!

  8. Hi. I’m confused by the conversion formula you use for the Dylos. Are you using the actual particles per cubic foot (the displayed numbers multiplied by 100), or the displayed numbers themselves. I’m referring to a DC1100 PRO. If the left displayed number is, say, 150 and the right number is 20, what does that equate to in PM2.5 micrograms/cubic meter?

    I’m a novice is this field, and basically am trying to figure out what readings are “good” for a residence. Thank you.

    • Hey Dave! We’ve tested a few particle counters under $50 (310RMB) and from what we’ve seen none of them are extremely reliable at giving accurate results. If you just want a particle counter that gives you something in the ‘ballpark’, so you can have a rough idea of what your indoor air pollution is, then you can pick up any of the particles counters in the 100-200RMB range (check out Taobao). They can give you an indication, but not a very accurate one.

  9. I am looking forward to the next test of air quality monitors, will it be available soon?
    It would be great if you added dB measurements to the descriptions of Original and Cannon purifiers.
    Also, how much is shipping to Denmark, by air or sea for a Cannon + 3 filters?

    • Thanks Ras!
      We’re currently working on a fundraiser so that we can buy even more pollution monitors! It should be launching in the next 2 weeks (at the latest, by the end of August 2017) so keep your eyes on this blog for more information.

      If you want information on shipping to Denmark please email Esther on [email protected] – thanks!

  10. “Since then, the market has exploded with new particle counters as cheap as 99 RMB. But are they any good?”

    Although I came here to look up your results on the Node… I must admit this line got my attention, and I was a little disappointed to not hear anything about anything in *that* price range. I’m on a budget here in Beijing (which is why your product appealed to me in the first place) and I’m *really* eager to find out anything (even less comprehensive) that you could say about the reliability of the cheaper stuff!

    When will you write *that* review? 🙂

    • Hey Edward, good question! We are as of right now working on a fundraiser campaign to raise some money to buy as many different particle counters as we can. Once we’ve done that we’ll test them all methodically and publish the results. We also definitely want to test the 99RMB ones! We have heard some reports that their accuracy is not great, and that’s also my guess, but we need to do the tests and see.

      Thanks for being patient

      • Why would their accuracy be ‘not great’? They seem to use identical technology but just lack a ‘cool’ design. That’s what Smart Air stands for isn’t it?

        • Good point, whilst one would assume a cheaper particle counter won’t be as good as a more expensive one, it’s not always true (just like Smart Air’s purifiers!). The thing with particle counters is they are inherently more complicated than a purifier – they contain lasers which require calibration and testing. If the technology was identical then sure, they would work just as well as the expensive ones, and that’s exactly why we want to test these counters to verify this.

      • Would love to see this trial. Any updates as to when it may be complete? Thanks for all of the great information!

        • Hey Tyler, we still haven’t launched the crowdfunding campaign, but we’re hoping to get it launched this winter. We’ll send you an update once we’ve launched the crowdfunder!

        • All three of these monitors should do a good job of measuring smoke particles, so I suggest you choose whichever one is within your price range, and if you want any extra features (like CO2 or forecasts)

  11. I read somewhere about “drift” in these sensors, and needing to recalibrate. What has been your experience over time with their accuracy? Can the Laser or Node be recalibrated?

    • Good question! From our experience all devices do drift over time and need recalibrating. Even the Dylos. We regularly send our Dylos units back to the company in the US to get them recalibrated for $45 a time. As for the other units, they don’t seem to have an official recalibration service. I reached out to the guys at AirVisual and they said spraying compressed air to clean the sensor is one method to help improve accuracy. If high accuracy is a requirement for a customer then they can recalibrate in their factory.


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