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Air quality monitors: paying more does not get you more accuracy

airgradient.com

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Re: Air quality monitors: paying more does not get you more accuracy

#31

Post by steve1977 »

sidmitra wrote: post #19
hammock wrote: post #18

Earlier quoted context omitted.

The same is true of digital bathroom scales. In fact almost all consumer grade digital scales have “fake accuracy” built into the firmware that ensures the same exact weight shows up when you step on the scale twice in a row, even if you pick up e.g a quarter-pound weight in your hand the second time

Yes, but do you(or someone else) have a recommendation of which scale does not do this? Something that's not consumer grade, but not "enterprise cost"

I made good experience with an Omron BF 511. As far as I know it doesn’t do this, would have to test though.

The bodyfat measurement is good enough to be usable and the same scale is working in our household for almost 10 years now I believe.

Re: Air quality monitors: paying more does not get you more accuracy

#32

Post by ahaucnx »

ruph123 wrote: post #29

I would not recommend the Airgradient diy kit to anyone. Have been using one for a while but the CO2 sensor is really unreliable and often spits out wrong values. VERY OFTEN. Last time this issue was wildly discussed by people using it e.g. in the link below which is using Prometheus but also in the forums of airgradient. All with no solution. https://github.com/geerlingguy/airgradient-prometheus/issues...

This was an issue we had in one of the previous versions of the kit. Since then we have improved the hardware (now at version 4.2) as well as fixed it in the firmware.

If you still have issues, please contact me through the link on my profile.

Re: Air quality monitors: paying more does not get you more accuracy

#34

Post by _zoltan_ »

ahaucnx wrote: post #32
ruph123 wrote: post #29

I would not recommend the Airgradient diy kit to anyone. Have been using one for a while but the CO2 sensor is really unreliable and often spits out wrong values. VERY OFTEN. Last time this issue was wildly discussed by people using it e.g. in the link below which is using Prometheus but also in the forums of airgradient. All with no solution. https://github.com/geerlingguy/airgradient-prometheus/issues...

This was an issue we had in one of the previous versions of the kit. Since then we have improved the hardware (now at version 4.2) as well as fixed it in the firmware. If you still have issues, please contact me through the link on my profile.

the above linked GitHub issue is still open.

Re: Air quality monitors: paying more does not get you more accuracy

#35

Post by trog »

newman314 wrote: post #13
bombcar wrote: post #12

Earlier quoted context omitted.

I suspect I know exactly which one you bought ;) I wish I could find a good source for "outside CO2 levels" as I think they've been elevated but I have no way to prove it (beyond my indoor sensor showing high).

Aranet4 is the way to go. Tried going cheap and getting a bunch of Vitalights later as additional monitors but ended up finding out that their results were all over the place. Returned the Vitalight. Kept the Aranet4. I do have plans to build a few Airgradients when I have time.

co2.click also worth a look: https://www.co2.click/

Re: Air quality monitors: paying more does not get you more accuracy

#36

Post by aulin »

hammock wrote: post #18
ahaucnx wrote: post #3

Author here. I wrote this article a few weeks ago after discovering that a well known air quality monitor in the market that retails for more than USD 1000 actually uses a PM module that costs less than USD 20. Often people assume that the more expensive, the better but as you can see in the article this is often not the case -especially when it comes to the accuracy of the monitor. If you are looking for an open sou…

The same is true of digital bathroom scales. In fact almost all consumer grade digital scales have “fake accuracy” built into the firmware that ensures the same exact weight shows up when you step on the scale twice in a row, even if you pick up e.g a quarter-pound weight in your hand the second time

I wouldn't say it's the same.

Low cost air quality measurement is difficult. PM is tricky but almost manageable with laser scattering, toxic gases at typical inquinant concentrations are almost impossible to get right with electrochemical sensors, no matter how much money you throw at them.

Weight measurement is easy, they could give you precise and accurate results but most customer base doesn't understand anything of physical quantities measurement and would panic they gained 50g in a minute if they showed up the real fluctuating values by stepping on the scale twice.

Re: Air quality monitors: paying more does not get you more accuracy

#37

Post by baq »

pachico wrote: post #33

This is not a joke, I am really asking: how do you measure the accuracy of an air quality monitor? Comparing it to another monitor? Creating an air pollution condition and seeing how close to that is the measurement?

Generalized, this is unsurprisingly a field of science: https://en.m.wikipedia.org/wiki/Metrology

Re: Air quality monitors: paying more does not get you more accuracy

#38

Post by psyklic »

ahaucnx wrote: post #3

Author here. I wrote this article a few weeks ago after discovering that a well known air quality monitor in the market that retails for more than USD 1000 actually uses a PM module that costs less than USD 20. Often people assume that the more expensive, the better but as you can see in the article this is often not the case -especially when it comes to the accuracy of the monitor. If you are looking for an open sou…

Interesting analysis!

Minor typo throughout: It's R^2 instead of R_2.

Also surprised the dataset doesn't include Awair's products!

Re: Air quality monitors: paying more does not get you more accuracy

#39

Post by rgovostes »

_zoltan_ wrote: post #34
ahaucnx wrote: post #32

Earlier quoted context omitted.

This was an issue we had in one of the previous versions of the kit. Since then we have improved the hardware (now at version 4.2) as well as fixed it in the firmware. If you still have issues, please contact me through the link on my profile.

the above linked GitHub issue is still open.

The above linked GitHub issue has been closed for over 6 months, and aside from that was posted to the wrong project rather than to an official AirGradient channel.

Re: Air quality monitors: paying more does not get you more accuracy

#40

Post by samtho »

AceJohnny2 wrote: post #28

It seems a lot of air quality monitors, such as the PurpleAir PA-II [1] , are just wrapping the Plantower PMS5003 [2], which is a turnkey particle sensor which integrates laser sensors, airflow, and MCU to perform measurements and spit out results on a serial bus. I'm pretty surprised by the lack of diversity in the "consumer" market. [1] https://www2.purpleair.com/products/purpleair-pa-ii?variant=... [2] available e…

I’ve used a lot of different sensors for random purposes and it’s almost always the same few companies (or a knockoff of them) at each the price point.

Building a sensor-on-ic is more comparable to the process that pharmaceutical companies go through in their R&D rather than traditional logic chip makers. It’s a lot of experimenting, use of non-standard materials, and pushing fabrication techniques to their limits. They don’t have to disclose how it’s made in the same way as pharmaceutical companies are required to, however, which means they have a monopoly on the tech until someone decaps the IC and reverse engineers it.

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