Shopping Guide: Air Quality Monitors

As you already know, I receive messages from readers of my blog almost every day. Their most common question is which air quality monitor should they choose. Most of the time in their message, they tell me that they go through Amazon to find a product, but they are confused from their reviews.

Carbon Dioxide (CO2) Monitors are a big hit nowadays due to the pandemic and because they are great tools at helping us understand indoor ventilation in order to mitigate the spread of the virus. Many new CO2 monitors pop up every day like mushrooms. Are they good, well …. you have to be careful!

No offense to Amazon or AliExpress or Facebook but most of their products are garbage for two reasons. Firstly, they are cheap products that come from China but without any quality control. Apple products come from China too, but Apple controls the quality of the shipping products. I have reviewed some cheap air quality monitors here on the blog just to justify their low price tag. Secondly, companies that sell these products don’t offer any kind of support nor updates. If the product has a small bug, you will stick with it forever. Many times the language they come with is badly translated or they come in Chinese if you are not careful enough during the purchase process.

Example of what Amazon considers Best Seller!

Another big problem with Amazon reviews is that sellers of the products pay people to give a positive review, read this article from The Verge here. As you can understand that makes the star system very unreliable.

Moreover, when you type “air quality monitor” on Amazon’s search engine, it will recommend you a product based on their agenda, which is the product that will offer them more money, and most likely it will be a sponsored product, like on the example above. I would never recommend someone to buy one of these three products. They don’t even have a brand name!

Don’t get me wrong respectable companies sell air quality monitors on Amazon too, but the average buyer cannot distinguish which products offer support and which ones don’t.

For the love of God, I have seen Schools and Businesses buying cheap CO2 monitor that end up in a drawer or closet because they are not able to keep a log file with the CO2 concentrations, so teachers and employees had to manually write the concentrations in a notepad.


If you want to buy an air quality monitor from Amazon, do it once you have chosen the products from unbiased sources. Avoid cheap products as their life span is unknown and very limited. Buy quality products from an ethical background company. Think wise about the sensors/services that will serve you the most and not opting for the one with the most sensors.

FIY, some DIY CO2 monitors that use quality sensors are better than the generic CO2 available on Amazon.


15 thoughts on “Shopping Guide: Air Quality Monitors

  1. Good article Sotirios. It might be helpful if sometime you listed what IAQ monitors are known to be good. I believe Netatmo, IQAir, Rad A3… Others? Is Awair v2 now reliable? And perhaps list popular ones that we know are bad such as Foobot. And then maybe those that are likely reliable but not yet tested enough?

    BTW, you might be interested in: Not sure if I’d mentioned it to you before or not.

    Liked by 1 person

    • Thank you for your comment.
      I try my best to evaluate monitors and sensors. Maybe in a future list I will present the SeeTheAir Evaluation Results but it’s gonna be very controversial.

      The article about ventilation and saunas is very good and very in-depth.

      Liked by 1 person

      • I don’t know that it needs to be very in depth. Mostly just a quick binning of those that;
        1 – You know are accurate and reliable
        2 – Are likely accurate and reliable
        3 – Are not or likely are not accurate and reliable.

        E.G., just give people some indicator of which ones are safe to buy. Preferably from #1. Maybe #2 if there’s a feature that one has that the purchaser wants. And help people to avoid mistakes with purchases from #3 or from #2 without some more in depth research.

        And then a note that if it’s not included that it is likely in #3.


  2. I agree; that research is important. And in the coming years more AQ measuring systems will be on the market /while/ the price performance improves. What you said about logging is a great point. Writing things down manually is not an option.

    Liked by 2 people

  3. hello
    can we bought somethingalready assembled from here
    and make it availible online in one or more platforms?
    i want to inform people through maps and be informed through map, push notifications and lcd screen if it is possible in Android etc.
    i can not make something by my self so i am looking for a ready solution.
    in the future i want to buy more and put them around Greece.


      • hello
        First i will buy one for outdoor and for sure later one indoor.
        About the question which sensors are important to me, i want to ask you .
        For sure the more sensors you have is better. but apart from what i will buy is it a good thought that we need the P.M. 1/2.5/10 for outdor and P.M. 1/2.5/10, co2 and Formaldehyde for indoor ?
        Leed me about what is basic, what is advanced.

        When you say support what do you mean? Are some of this plug and play or do i have to install a firmware or to update through “weird” process ?
        I prefer to pay a bit more to have more sensors, interface and make my observations public .
        Sory maybe it sounds silly but i am newbie.

        Liked by 1 person

      • The link you shared with me has DIY AQ monitors that were already assembled by someone which means in case the sensors stop working then there is no support from the company on how to fix them or even a warranty. It will be plug and play and you won’t need to install a firmware. Here it will be very important to know your budget. If you prefer, please email me via the contact page on the top on the site in order to have a private conversation.

        More sensors isn’t always the best approach especially for inexpensive devices.

        For indoor, PM2.5 and CO2 are more than enough.
        For outdoor, PM2.5 is also enough.

        You don’t need to apologize, I am here to help you.


      • an important part is loading the data onto a mapping service so that your info can be referenced over time; shared with others; and compared to others.

        after a week you will feel like watching paint dry is more exciting. buy something you can set up and let run and not worry about!

        Liked by 1 person

  4. As the topic of DIY sensors came up:

    We have open-source and open-hardware build instructions for a DIY sensor. That sensor uses the Senseair S8 CO2 module which is of high quality (I believe the Air Visual air quality monitor uses the same sensor). It can also measure PM2.5, Temperature, and Humidity.

    We already had quite a lot of people building these sensors -some in schools with students.
    I am more than happy to send See The Air readers some free PCBs to build these sensors (will just charge for the postage).

    Please feel free to contact me if you are interested.

    Liked by 1 person

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