My opinion about VOC Sensors


It has been quite some time now since I have had 2 devices with VOC sensors and I want to express my honest opinion about them. I am not going to talk about the brands but only I will discuss my opinion if the VOC sensor have a value to the user.

One of devices displays the measurments in ppb and the other one displays an index value from 1 to 5. At the beginning I was thinking that ppb is a better way to display pollution inside the house “more accurate” but after a while I understood that it doesn’t matter because index values are a greater and easier way for the avarage users to understand that.

VOC sensors measure a variety of harmful chemical compounds with carbon atoms (aka organic) like Acetone CH3(CO)CH3, Benzene C6H6, Ethylene glycol C2H6O, Formaldehyde CH2O, Toluene C7H8,Xylene C8H10, etc… but also other non harmful VOCs as well, for instant when I clean my house I use distilled water and organic essential oil, tea tree to be more exact. Tea tree’s components are Terpinen-4-ol C10H18O, γ-Terpinene C10H16, Aromadendrene  C15H24 etc… all with Carbon atoms which they trigger the VOC sensor. As you can understand if you don’t have the chemical knowledge for each particle in the air, you might get confused by the alerts your VOC sensor gives you.


Many users have told me that they indeed feel confused by the readings the VOC sensor gives them. The researchers on the other hand say that at least you know the concentration of some organic gas is higher than normal, and you can start thinking about why that occurs.

I am not in favor of researchers’ opinion, the user has to know excaly what isn’t going well with his air quality and not guessing.

13 thoughts on “My opinion about VOC Sensors

  1. I would argue that with all these IAQ measurements, the user is gets an indicative measurement and then tries to diagnose the problem (yes, probably unsuccessfully or incorrectly at times). Not are particles are harmful, yet PM2.5 sensors have been widely accepted. This is a similar proposition is it not?

    Two other options exist. One is to detect an array of individual gases, this is done now but is prohibitively expensive. The other is to detect specific unhealthy compounds, such as CH2O, that are prevalent in daily life, thus eliminating the confusion of deciding whether the alert warrants action or not.

    Liked by 1 person

    • Hi Scott, yes a sensor that measures only Formaldehyde CH2O or CO or O3 would be much better and accurate on how people understand air pollution. I can’t compare PMs and Gases because of the different anatomy they have.


  2. I tried the egg air quality 03/SO2 and NO2/CO sensors – it was completely useless. Are there any reasonably priced Formaldehyde CH2O or CO or O3 sensors?


    • Hello Yaniv, only Formaldehyde will be hard to find. In general they are expensive and rare to find sensors. There are some DYI devices with reasonable prices otherwise the prices can surpass the 400$ tags. May I ask why you are interested into these sensors in particular?


      • Thank you for your response. I was interested in measuring the off-gassing of furniture or foam (e.g. most baby sleep bassinets have foam mattresses). Do you think Awair is enough for that?

        Liked by 1 person

  3. Also, what do you recommend for a good O3 sensor. Although, I am not sure what action I can take for bad ozone levels. I guess it would be nice to see if my negative ion generator (which was marketing as not producing any ozone) produces any ozone.

    Liked by 1 person

    • Hi, all purifiers with ions generate Ozone even a simple fan’s motor can generate Ozone. Some of them generate more or less than others.
      Without personal experience I think the Aeroqual Series 300 is a good portable monitor for Ozone or other gases but it gets pricey.
      Also there is a station monitor that claims that has various sensor like O3, CO, CO2 inside. It is called uHoo and is more affordable.
      In general for you to get an rough idea a good O3 sensor can cost +$150.
      The only thing we can do depending where we live is to ventilate our homes minimum twice a day.


  4. […] Awair is the only device which features a VOC sensor. Some people find value on it so it’s nice to have it if you need it. It measures in ppb. To be honest I don’t trust the VOC sensors in general and you can read the reason on this post: My opinion about VOC Sensors. […]


  5. Have you tried blowing a deep breath inside VOC’s sensors? Beside the fact that CO2 goes up to the top, also VOC’s go up really a lot.

    Here in Athens at night we have to close the windows because of the fireplaces smoke outside. And when closing the windows, CO2 goes up over 1000. VOC’s go up too, but it’s not from furniture or anything else in our home. It is due to our own breathing activity. We naturally release lots of gases along with CO2 from our lungs, and these are sensed by the VOC meters. Sorry if I say this, but even a small fart makes the VOC’s measurements go crazy! So the VOC’s sensors don’t make much sense to me, if we don’t know which gases they measure.

    Liked by 1 person

    • Exactly! Interestingly, some scientists have conducted studies measuring an individual’s breath as exhaled breath condensate is a potential rich source for countless biomarkers that can provide valuable information with the help of VOC sensors.


    • Blowing right into *any* sensor will probably mess up its current measurement, be it temperature, humidity, co2 or voc sensor. Many voc sensors in air quality home devices are just cheap low quality crap like estimating voc from co2 concentration and not direct measuring this is why breathing elevates it as well or complete junk that gives nonsense values. But we shouldn’t blame the idea of measuring voc because it’s a very important aspect of air quality!


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