Checking Your Indoor PM2.5, Cheaply, With The Laser Egg

UPDATE January 4, 2016: Here’s a great review article about PM2.5 monitors: click here; they praise the Laser Egg but also discuss its limitations.
laser-eggI’ve mentioned often that I feel it’s important for people who use air purifiers to make sure your investments are working well. For me, this means always keeping your indoor air PM2.5 concentration under 10 ug/m3 (read my explanation here). The only way to know this is to have a PM2.5 monitor to check your air. We can spend so much money on air purifier machines — but how are we sure they’re on the correct speeds, or in the best part of the room, or that the filters aren’t clogged and need to be replaced early? And how do you know if you need to increase their speed when the AQI is airpocalyptic?

You certainly can’t rely on the built-in PM2.5 sensors that many air purifiers have, as the vast majority I’ve seen are inaccurate and basically useless. No, the answer has always been simple — and complicated. You’ve always needed to buy a separate PM2.5 monitor, but the best ones are wildly expensive. For a few years I’ve been using a popular, more economical choice from America called Dylos, but their data was uncommonly difficult to download and convert to something we layman could understand.

Now, finally, we’re starting to see some reasonable options, and I’m thinking specifically of the new Laser Egg, an air quality monitor from Beijing-based environmental company Origins, set up by an expat couple. Many of you are already using this Laser Egg, which is available for a wonderfully reasonable price of 499 RMB. I’ve been testing a few of these Eggs for a few weeks, and I can finally say that consumers now have a real option for testing your air at home (or work, or schools, etc etc).

laser-egg-appI have some highlights about this Laser Egg:

  1. The Egg already has saved me tens of thousands of RMB in air purifier costs, as I’ve recently replaced my home’s air purifiers with a far more economical machine (the Xiaomi), and the Laser Egg data proves that these new machines are very effective. (I will blog about this soon).
  2. Their app (Breathing Space) is very useful, as you can sync all of your Eggs to your home wifi, and you can access their data anytime, anywhere in the world.
  3. The app also shows the local outdoor air, so you can immediately compare indoor versus outdoor air. Very useful.
  4. You can choose to monitor the AQI from China or from the USA, or even better, the raw concentration of ug/m3. I always use concentration because I can quickly glance and see if it’s under 10 or not. Plus it’s the most evidenced based, as 10 ug/m3 is the official recommendation by the World Health Organization, and then you don’t have to deal with the politics of AQIs, which are totally different in every country.
  5. You can also use the app to export the data to your email, and create snazzy Excel graphs like the one below. For example, the Egg’s weekly data spreadsheet has 5-minute interval data on PM2.5, PM10, humidity and temperature. Data geeks like myself will love it.
  6. Its battery charges by USB so you can unplug and stuff in your bag and walk around town with it, checking out your favorite stores and also the outdoor air anywhere.
  7. You can keep it on 24/7, in sleep mode, and always access the data via your app or the screen.
  8. The app also can send you instant messages warning you if your air is suddenly getting worse. For example, I was at work and got a cell phone pop-up warning that my front room air was worsening, which I confirmed on the app’s graphics. I called my wife at home and she realized that all our Xiaomi purifiers had been shut off after a power outage. I turned them all back on (using another app from my air purifier), and sitting in my office I watched the app to see my home’s PM2.5 improving minute by minute. How cool is that?
  9. You can also rig it to check pollution masks, sort of. See the video I made below, using the Laser Egg to test an incredible new pollution mask I’m helping to design, called Freeair. It’s a battery-powered outdoor pollution mask that delivers pure air via a tiny fan and an astonishing new filter, classified ULPA (Ultra-Low Particulate Air), far superior to N95, N99 or HEPA filters. It filters basically 100% of PM2.5 and also filters much smaller ultrafine particles by 99.99999%. As you see in the video, literally every molecule of pollution is filtered out. You’ll definitely be hearing more about Freeair soon.
  10. You can quickly check for leaks around doors and windows. You all have already sealed your windows and doors with the very inexpensive rubber strips, yes? If not, read this and then come back. Anyway, one horrible night with AQI over 400 I noticed from the Laser Egg app that my baby’s bedroom PM2.5 was strangely high. And sure enough, the rubber sealing was coming off a part of a window. I resealed it, and voila! Happy baby.
  11. The Laser Egg looks pretty cool, actually.

So how reliable is the Laser Egg, and is the price too good to be true? For accuracy, you can check out the company’s own comparison testing with the US Embassy’s monitor, but perhaps you’d rather see more independent tests such as this reviewer’s comparative testing with much more expensive sensors. It’s in Chinese but just from his photos you see they’re generally the same. I’ve discussed the Egg with some pollution experts in Beijing and they’re generally supportive but mention that humidity can mess with the numbers a bit, and also putting Eggs side to side will show slightly different numbers. But in general, on a consumer level, it certainly does what it says it does.

I personally think the Egg could be improved, but it’s accurate enough for me and very impressive for a first version. And right now I definitely have stopped using the Dylos and will only be using the Egg from now on. If you’re interested in the Egg, you can buy on their website here or also via their Wechat directly (ID: originstech). I’ve also seen it behind the cash registers at April Gourmet and Jenny Lou’s. Think Christmas stocking stuffer…


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Photography: richardsaintcyr.com
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36 thoughts on “Checking Your Indoor PM2.5, Cheaply, With The Laser Egg”

  1. Thanks for the recommendation. I was very close to ordering a Dylos, but was concerned that it would be difficult for my family to interpret when I’m not around (traveling). I’m not looking for perfect accuracy, just something clear and better than the air purifier indicators. By the way, I also ordered the Midea and Xiomi air purifiers per the recommendation from your other article (Air Purifiers under 1,000RMB). I like the Xiomi better and will likely order another.

    1. Yes, the Dylos is surprisingly user-unfriendly and I’m glad finally something better has come along. The Laser Egg app is great, and perfect for family members to use.

    1. No I’ve never seen this, looks like a very small monitor. Perhaps too small? I have no idea, I don’t even see a link to buy it…

      1. I suppose the price is too good to be true? Let’s just wait and see some reviews. A lot of people are coming up with new monitors, I saw a great one recently almost ready for sale from the Airvisual team, https://airvisual.com/

      2. The Airburg doesn’t have an LCD monitor (it uses your smartphone to display the), that’s one way they were able to cut down on the cost. I’d like to try this out (it would be great to take with me on the go), however they are currently sold out.

      3. Don’t be put off by the small size – all that is needed to build one of these things is a laser, a light detector, an air channel, a fan, some circuitry, a battery, and an enclosure.

      4. I agree with this. It seems the Laser Egg is not particularly innovative, rather it has taken a fairly basic concept and pre-existing technology and wrapped it in very clever marketing. I’m sure it works very well but you’re paying extra for the LCD, the attractive design, the extra services and of course the marketing. The Airburg seems to use identical technology without the bells and whistles.

  2. I just went around my apartment with the egg showing my housekeeper what happens if she leaves certain doors open. I also showed her how to vacuum my filters. She’s amazed at the difference it made instantly, and the simple thing of putting a towel in front of the bathroom door to slow the particles coming into the bedroom. Without the towel it was almost 180, and rising, and with it it was instantly 85. We have other leaks we’ve identified with the egg and are fixing them ASAP.

    Even with the price hike, these are invaluable if you really want to get your home to a certain level of air quality.

    1. That’s a really interesting idea, to educate our ayis as well. There are so many uses for a portable monitor. For example, what about all our offices and schools, and coffee shops, etc etc? We need to be showing these businesses data…

  3. It’s funny, I have been in Beijing for 6 months and more of less ended up with similar conclusion than yours; I started using a dylos, but changed it to the an “egg” recently. I also concluded that the Xiaomi were the best purifiers. I am quiet satisfied with where I am as far as PM2.5….But the quest for pure air is never finished…I recently purchased a CO2 monitor, and realized how bad air can get inside when there is not enough aeration…we were getting to 5000ppm of CO2 in our home when the healthy limit is 1000ppm! (and studies have shown that decision capabilities reduce significantly above 2500ppm)Obviously….it is not always an option to open windows in beijing when you have children at home…so we found the alternative…purifying plants….surprisingly enough it works: 8 plants per person make the appartement neutral in CO2…I thought Ifinally had it all, low PM2.5, lowCO2levels……Then we purchased a formaldehyde sensor, and noticed that we were at 0.5ppm instead of 0.1ppm…after a lot of investigation we found it was due to the d-lemonene in our “green and healthy” cleaning product, combining with ozone and making formaldehyde……………The quest for pure air is never finished 🙂

    1. Wow, you test as much as I do! That’s interesting about the CO2 and how the plants are helping. People are always concerned that if they seal things up too tightly then CO2 could creep up, so plants definitely could help. I think the perfect sensor would combine PM2.5 with CO2…I’m sure someone’s working on it…

      1. I would say a PM2.5, CO2 and VOC sensor would be ideal. The 3 combined should give a good idea of air quality in an appartement. Because you can get thePM2.5 and CO2 right and still have very bad VOC’s. Actually on JD.com there seem to be a lot of these combined sensors coming up. I ended up buying them all separately as I was becoming aware of new threats

        The plants indeed amazed me , they really maintain the appartement at 1000ppm CO2 continuously. I used a mix of Snake plants (which make O2 at night), Areca plants and spider plants.Most of these plants need minimum maintenance, so it is really easy.
        On top of that..it gives a refreshing atmosphere to the apartement.

        The VOC and formaldehydes are still a mistery in my house. they drop both to 0 ppm if I open the windows for an hour even on a very bad day (How can VOCs be at zero when AQI is around 300 outside ??mistery). But both HCOH and VOC come back to 0.2ppm and 2.0 ppm respectively after sometime…….sometimes it stays at 0ppm for 3hours and then suddenly it starts raising. I I still do not understand where it comes from. the D-lemonene does not seem to be the only culprit. Showers ,deodorizers, even cooking in an oven seem to build this up….still a lot of measures to do:). What I do not understand is that non of the air purifiers or plants really seem to be bringing it down…neither the V5cell of the IQ air,neither the formaldehyde filter of the Xiaomi’s……..

        So, my focus right now is to figure the VOC and formaldehyde’s out…Hopefully there is nothing that will pop us as a new concern in the air.

        The ultra fine particles seem to be filtered by purifiers ,the ozone and NO2 seem to be tackled by the carbon filters;humidity is handled by humidifiers.
        But who knows……there is probably something else that no one of us is aware.
        I hwave a 3 years old boy…….So my passion comes from protecting him. I like all what he learns here, different culture, different languags,…but I would hate to do it at the expense of his health.

      2. Hi Patricia,

        Thanks for sharing your findings. I’ve also been thinking about CO2 as I’ve started to seal my door and windows due to the horrible pollution lately. I’m pleasantly surprised that adding some houseplants have made such a difference – I will definitely get some more plants. Could you tell me which CO2 monitor you used? There are many different kinds available only but I have no idea which ones are accurate.

        Regarding VOC/formaldehyde – the main sources for these are inside your home, that is why the levels drop when you open the windows. Also, VOCs/formaldehyde are not included in the AQI measurement. Actually, formaldehyde at 0.5ppm is really high – the national limit in China is 0.08. Was your home recently renovated or did you purchase new furniture? When we renovated our apartment, we had a lab test for VOCs and they were all safely under the limit. The other explanation is that your monitor is inaccurate – in fact I have not been able to find a detailed explanation of how these portable monitors are able to measure formaldehyde, which makes me skeptical. Have you tried taking a reading directly in front of the output of your IQ Air? If the levels are still. high, then I would suspect that it is actually measuring something else.

        By the way, why do you have ozone in your home? I would be concerned about that too.

      3. Hello,

        for the CO2 sensor I purchased the brand: CEM , model DT-802 on JD.com.
        the brand seemed to be popular. I do not know how accurate it is but outside values seem close to what is published for outside air 300ppm on a good day, 500 ppm on a bad day….and the trending seems correct…it goes up 1000 ppm when you cook. With 3 persons in a house, no plants, it was going up 150ppm per hour…the more the people,the quicker it goes up. Since I have the plants ,it goes up 20ppm an hour during the day, and it goes completely down the night (I mostly have snake plants that work at night). the plants stabilize the environment at 1000ppm.I never understood why it does not go lower (unless I open the windows and then it drops back to 400ppm)

        For the formaldehyde…I am leaning towards your conclusion. The sensor most measure something else. It goes up significantly if we drink a glass of wine (I guess the alcool evaporating in the atmosphere), it goes up with food in the oven (I know there is some natural formaldehyde in the food…but I would be surprised that it brings the whole appartement up).
        On top of that, the IQ air and the Xiaomi (with a formaldehyde filter in it) do not seem to change anything to the measure, even if I put the sensor at the air outlet/

        I am leaning towards getting an outiside firm in to test, or buy some of the “testing sticks” sold in europe or the US.

        The apartement was renovated with new plywood 6 months ago..so I know that is a source for formaldehyde…but if the floor was really giving away, I would see a continuous trend up…which does not seem to be the case… Thanks for your advice.

        Patricia

      4. As far as the ozone, this is an interesting story to share.

        I leave in an appartement that has 100% recirculating air. This is super for polution,but not ideal for fresh air.All fresh air has to come trough the opening of the windows.
        Inside the circulating air was an Electrostatic filter. Very effective for PM2.5 filtration….but caused me quiet a trouble the first week I arrived in beijing.

        Electrostatic filters create a little of ozone…but in a closed loop they build up quiet some ozone!…so the first time it ran for 12 hours I ended having my baby with a big “asthma type ” of crisis and had to run to the ER in the middle of the night.

        Since then, I am concerned with overall presence of ozone or NO2 in the outside atmosphere…in the summer it gets quiet high, and I wanted to make sure I do maintain reasonable levels in the apartement.

      5. The iKair (available on jd.com) allows you to combine various sensor modules together, including PM2.5 and CO2, however I no idea as to its accuracy.

  4. The Freeair mask looks very interesting. Is it available for children? Is it available in Beijing? I have been looking for some time already for the perfect children mask, with no success.

    1. Yes the new Freeair mask is amazing, it literally filters out 100% of not only PM2.5 but also much smaller ultrafine particles (tested 99.99999%). Check out the video I made here http://mp.weixin.qq.com/mp/video?__biz=MzA3MDczMDYxOQ==&mid=400717470&sn=702485dad2b6f66006a510187504f19e&vid=l1301kckpdb&idx=1&scene=1#wechat_redirectCan I’ve been helping them as one of their medical advisors and I’m very impressed with them. It’s a battery powered mask which uses an ULPA filter (far stronger than HEPA) to deliver air to the mask via positive pressure. The current model is just on the market, in China for 7,999RMB, you have to call them 400-706-8211 but I don’t think anyone speaks English. Maybe easier — and cheaper — for many readers is to buy from Amazon USA for USD $699 and ship to China: http://www.amazon.com/FreeAir-Personal-Air-Purifying-System/dp/B010MPIEMI/ Right now I don’t think this version has the kid’s size but I’m told there will be a smaller version within 6 months which should have kids sizes. They’re also designing a super cool cover which goes over baby strollers, and you can attach the Freeair and pump clean air into the stroller while outside. I know a lot of parents who would love that option (including me)!

      Otherwise there is no “perfect children mask” as we all know, so it’s still a sad state of affairs. My kids are now two and a half and 16 months and Alex won’t even wear the Vogmask anymore 🙁

      1. Hi Richard

        Just saw the video~ Is the freeair comfortable? How do the filters work? how long they last/will the machine notify to change filter etc etc… and of course how much would it cost for the filter change? Just checked out the amazon link but there isn’t much info on it.

        Would love to get this for my father who has respiratory problems (we live in Shanghai) and he dislikes wearing the 3M masks and Vogmasks… best I can do now is make sure he has a air filter device at the office and home (we use philip and blueair waiting for the new xiaomi air 2 to come out! exciting stuff!)

        I’m sure you get this alot but thank you for all the effort you’ve put into this blog and publishing/posting your and other peoples tests of air filter devices and machines. It helps us consumers both better understand our environment/situation as well as understanding the market and the products out there- informed consumers pushes industries to produce better products-at least thats how I see it!

        thanks again and happy holidays! will continue to follow your blog!

      2. Hi Maggie, thanks for the kind words. For Freeair, there’s more information at Freeair.com but it works by filtering air through an incredibly effective ULPA filter, and a fan blows the cleaned air through a tube to your facemask. It works unbelievably well… but no it’s not super comfortable to lug around and wear a big sidebag or backpack. So that’s an issue, but it’s still an incredible machine…

      3. Isn’t there a risk of turning a legitimate attempt to breathe clean air into a case of OCD? The 3M mask you wear filters 99.6% of particulates and the annual average pm2.5 readings in Beijing are about 80 ug/m3, so on average you’re breathing in only 0.32 ug/m3. Even on an Airpocalypse day of 500 ug/m3 you’d still only be breathing in 2 ug/m3. Looking at your health from a multifaceted perspective, isn’t the social ostracism of walking around dressed up like some kind of fighter pilot in a sci-fi movie likely to cause more damage than that extra 0.3 ug/m3? Studies show that socialising with other people is good for our health, but how can you socialise with that attached to your face? At a cost of approaching $1000, it’s never going to get mass appeal so you’re always going to be looked at as the weirdo with the jetpack. I doubt that’s good for anyone’s health.

      4. That’s a totally valid point, and I was definitely thinking the same thing when I tried it on for the first time. It does indeed make air pollution feel even more scary, and maybe that’s not a good psychological thing. That’s why I’m pressing the company to make a much smaller (and cheaper) version which should be out in the next 6 months. But it will still have a hose going to the mask, which will always be a strange thing for people to see on the street. So of course those types of masks are not for everyone, even if they could afford it. But having said that, when the air is super bad over 300, I felt much safer wearing the Freeair and there’s a HUGE psychological benefit in knowing FOR SURE that you’re breathing in perfectly clean air. I totally don’t care what people around me think, especially at that airpocalyptic moment. No one is living my life except me, and if I feel healthier then I’m going to do it. And I would think a not small percentage of bikers, joggers, commuters, etc, also wouldn’t care less what people think, nor should they. And certainly anybody with serious lung or heart disease would also be interested in something like Freeair. People have the right to breathe clean air, and if these types of masks get them there, then I am happy for them.

        Also don’t forget that the Freeair is rated 99.99999% effective down to 10 nanometers, which is orders of magnitude more effective than any N99-type mask on the market. None of those masks even mention ultrafine particles. This 10 nanometer size also gets every bacteria and virus, and in a pandemic like Ebola or bird flu, these types of masks could literally save your life. The SARS virus for example is 80-90 nanometers in size, and the Freeair would suck up every single virus (their official virus testing showed no detectible virus particles on all test results).

      5. Yup!Dad’s got pulmonary fibrosis… recent diagnosed last year- doctors in Shanghai are attributing it to the air pollution here.

        I can’t wait for a smaller version of this-will definitely seriously consider getting it for him. Very worried about the weight and bulk of the current freeair atm.

        I’ve checked out the site just now and I really have to say it’s pretty shit. Can’t find any information on the product….and when i hit learn about Freeair I get sent to the ‘about’ page. When I hit Learn about our Products I get sent to meet the doctors page….

        Hopefully we’ll get some more information with the new smaller product!

        Thanks again for all the info Dr. Richard!

      6. Hi Maggie, yes I agree, as as website and marketing person myself it’s quite embarrassing to have a poor website. The testing data isn’t even uploaded yet. That’s party why I haven’t written a full review yet on my blog, I’m waiting for them to get more professional. I’ve mentioned them recently, informally and quietly, because the pollution was so horrible that I wanted to at least let people know about this very new product.

  5. In regards to humidity, most particle counters I’ve seen including a humidity sensor and are supposed to be able to compensate for humidity in the particle reading.

  6. Thank you Dr. Saint Cyr for your detailed report and how useful the egg can be in our quest for clean air. I’ve been testing several eggs and using them in my home for 3 months now. While the eggs provide very useful information, we should all be aware of some of the product shortcomings, especially the false sense of safety that we get from its data. I saw that your target is 10 µg/m3 in your house and I’m afraid that you’re getting erroneous data from the egg. Hence this comment on your blog.

    My testing setup was composed of my own 4 eggs and 1 TSI DustTrak Aerosol + 1 Particle Plus that I borrowed from my company’s factory. At first, the eggs performed relatively well in the range 20 µg/m3 (US AQI 60) to 100 µg/m3 (AQI 170). Below 20 µg/m3, we can observe serious discrepancy against the 2 professional devices, by almost 50%. When the egg shows a concentration of 8µg/m3, we’re actually closer to 12µg/m3. Similarly when going to very low values, the egg has a tendency to show very quickly a concentration of 1µg/m3 while the professional devices still show 3-4µg/m3. That’s a 3-4 fold difference!!! Consumers should be aware of this fact and not assume a sense of safety.

    In higher concentrations, the egg has the opposite problem for concentrations above 100µg/m3. The egg shows much higher values by roughly 50% more than the professional devices and the U.S. embassy. I live 800 meters away from the U.S. embassy and I can assure you that the data is far from matching the U.S. embassy during pollution peaks above AQI 170. In higher concentrations, I don’t think the problem is so important because the air is very bad anyway and we usually take our own protective measures.

    The second big problem to be aware is that the eggs’ calibration drifts very quickly. After 2 months of usage, the difference between my 4 eggs is significant in the 20 µg/m3 to 100 µg/m3 range. During my measurements, I got over 40% drift (+ and -) against the professional machines that are regularly recalibrated. In daily usage, the eggs against other eggs also show major differences of more than 100% (I have one egg showing 50 µg/m3 while another one shows around 100 µg/m3). In lower concentrations below 20 µg/m3, the drift is even worse and I really feel that I lost any trust in the low concentration figures. I will keep monitoring the drifting in coming months and see if it keeps drifting at a similar pace.

    My conclusion: the egg is a very interesting consumer product, but we need to remember that it remains a consumer product with its qualities and faults. I think the most important is that we should all be aware of the egg accuracy problem in the lower values and the serious calibration drift. It’s critical that we don’t have a false sense of safety, especially for our children.

    As for me, I’m still using my 4 eggs at home, they are still much more convenient than industrial devices. They are particularly useful in higher concentrations to alert me when my rooms are in the red. But in the low concentration levels, I don’t trust their data anymore.

    1. Can you explain the point you made about calibration? I thought it just counted particles so why is calibration necessary and how does it work?

      1. Matthew, you raised an interesting point. Light scattering devices (like Dust Trak or the egg) indeed count particles, one at a time. However, there are many effects that needs to be taken into account: air flow intake, laser quality, photo sensor quality, formula to convert particle count to concentration, etc. I don’t even mention external factors like humidity, pressure, temperature, pollutant speciation, and many other ones.

        Every part of the sensor has slight performance variations, and put together they will deliver a very different output figure. The calibration process is there to mitigate the differences by aligning the sensors to a reference measurement. The quality of the sensor components and the calibration are the most important aspect of a sensor.

  7. I bough xiaomi air purifer rencently, but it was proved to be useless after tested by my monitor.I opened xiaomi air purifer whole night,but it still doesn’t have any change of the air quality in terms of pm2.5. Actually many people who bought it have dounted whether it’s useful. I returned my xiaomi air purifer and start looking for something else.

    1. My own data speaks for itself, but everyone’s welcome to try on their own, of course. If I may ask one question, which apparently isn’t so obvious — you took the plastic off of the filter before using it, yes? That seems like a very simple question but actually two people I know kept the plastic on accidentally and thought the machine wasn’t working…

  8. You mention that humidity and temperature are also provided when exporting the file, however when I exported the weekly data I only got pmi2. 5 and 10 data

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