Air Quality Monitors for VOCs

Ethan · July 1, 2024, 4:31am

When it comes to indoor air quality monitors, there are generally three pollutants that people care about:

Particulate matter (PM0.3-PM10)
VOCs (volatile organic compounds)
CO2 (carbon dioxide)

For some, CO and radon sensors are also important, but I’ve found that most readers ask me to recommend a monitor with the above three sensors. While I’ve discussed CO2 and PM sensors at length, I thought it would be interesting to discuss VOC sensors in air quality monitors because they have a few caveats that few people know. They shouldn’t be trusted with absolute values - only with identifying trends. Why? Let’s discuss.

At the moment, the two most popular VOC sensors you will find in many indoor (and outdoor) air quality monitors are the Bosche BME680 and Sensirion SGP30, SGP40 and SGP41. Across all of the monitors I’ve reviewed in the past few months, I’ve seen one of these sensors in every monitor that monitors VOCs. In other words, they’re very common and used all across the industry.

Many people don’t know that these sensors show an index by default - not an absolute value. Below is an explanation of the index used by default for the BM680.

From Bosche BME680 datasheet.

In short, since the absolute values from VOC sensors aren’t very reliable (more on that soon), the companies that produce the sensors have generally opted to use indexes instead. In Bosch’s case, the VOC sensor adapts and calibrates itself frequently to set new baselines. This means an IAQ of 50 should always mean ‘typical good’ and 200 ‘typical polluted’ regardless of your environment. In other words, this number helps identify trends but not absolute values.

Sensirion VOC index from SGP41 datasheet.

Above is an explanation from Sensirion that recommends that air quality monitor manufacturers don’t use the raw output from their VOC sensors but rather use the Gas Index Algorithm. This algorithm functions the same as Bosch’s and sets 100 as the baseline ‘average’ air quality over a set period (which manufacturers can adjust). Therefore, any number below 100 indicates improving air quality, and any number above represents worsening air quality.

So, why do these manufacturers recommend this approach? It’s because consumer-grade VOC sensors aren’t very accurate unless you know the exact VOC composition of the measured air. This is because VOC sensors are more sensitive to certain compounds and less sensitive to others.

Metal Oxide VOC sensor

The above image from Sensirion shows how a metal oxide sensor (all of the VOC sensors mentioned in this post are MOX sensors) has different selectivity towards individual VOCs.

As you can probably guess, since MOX sensors have different sensitivities to different VOCs, and we can never know for sure the exact composition of our indoor or outdoor air, an absolute VOC concentration is not particularly useful or accurate. While many older VOC sensors (and some current ones) do give an absolute value, and even the sensors mentioned in this post can be adjusted to show absolute values, they’re not accurate and hence the choice by Bosch and Sensirion to use a relative index instead.

Based on this information, I don’t think anyone should choose a consumer-grade monitor based on VOC performance. None of them are particularly accurate, and the VOC concentration recorded by the device should be used only to identify trends in indoor air quality.

The IKEA Vindstryka shows only an up arrow (increasing), a side arrow (stable), or a down arrow (decreasing) for VOC levels. While I didn’t realise it then, this makes a lot of sense with the limitations of VOC sensors in air quality monitors.

One final note is that since these sensors regularly readjust their baselines (depending on the period set by the air quality monitor manufacturer), overall trends shouldn’t be trusted - only short-term trends over a day or less. Some monitors will allow you to adjust the autocalibration period, but it’s not common.

At the end of the day, having a VOC sensor in an air quality monitor is useful, but it’s important to know the limitations and caveats of such sensors. If you have any questions, please don’t hesitate to ask below!

oBi1 · August 26, 2024, 2:51pm

Hello Ethan, thank you for the above! I stumbled upon this while searching for a solution. Honestly, I’m getting really anxious that we run some kind of huge health risk and I feel completely unable to change it!
I’m hoping you can share a thought or two if it suits you.

Background
Up to end of 23 challenges with dry eyes, throat etc. Some doctor visits but I thought maybe look at air quality inside (especially now we are working from home most of the time). This was some 2-3 years ago.
I bought a UHOO Indoor air quality device seeing it has quite a nice set of measurements. I saw mainly two things:

very high CO2 readings (mid-70s house, ventilation manual) especially during night.
TVOC levels going extreme into tens of thousands.

This was part of our deliberations to do a home renovation. Q1 of 24 this happened and I had them install a per room ventilation system (intakes) with per floor an outtake from a company called Climarad. It has soem filters in it and can get quite high in volume if pushed. I also installed an LG air conditioner that is supposed to be able to demoisturise and clean air.

Recently we have been moving back in and I found my Uhoo device again. Installed in our bedroom and you can probably guess:

CO2 much much better. Two peoplesleeping it gets to 1500 or so at night, but that is a matter of tuning the device I believe
TVOCs still going through the roof!. Very hard to get down.E.g this night climbed to 7,700 ppb. It took my ventilation at 4 out of 5 power and the LG airco with cleaning 7 hours to get it down to 1500. At that point it didn’t seem to go down anymore. Switching the vent to auto it climbs back quite fast (to 2,000 in 40 mins).

I’m very concerned especially as I read that it’s very hard to determine the origin or actual TVOC item (is it even a dangeruos one?)

I was thinking maybe my UHOO is broken, so I could buy another device like the one you have been recommending (qingping) but I fear that will not really tell me a lot as it seems to only use running average of the current situation.
let alone it showing me the source or direction I have to look.

I’m talking about the attic, not cooking even close to the room. Not a painter or sculptor or something with beauty products. just an office clerk working at my computer.

any thoughts would be so welcome!
KR Owen

Ethan · August 27, 2024, 2:34pm

Hi @oBi1,

Firstly, thanks for joining the forum! I hope I can help with your question. I can understand your worries, and it’s certainly possible that air quality is impacting your health and wellbeing.

Firstly, yes, this needs to be kept in mind. As you’ve already read my first post in this thread, it becomes quickly apparent that low-cost VOC sensors are very lacking as it’s impossible to tell exactly what VOCs constitute the final reading, and therefore, if it’s actually something to worry about or not. With that in mind, I personally would still be concerned about VOC levels that high as they could point towards a bigger ventilation issue.

I forget exactly how the uHoo monitor works, as it’s been a long time since I used mine (it’s in a different country right now!), but I believe there is a calibration period when it’s first turned on, and I wonder if that could have influenced the final readings. That said, if VOCs were present during calibration, and they’re climbing even more now, it still seems to point to an issue.

Concentrations like this are still very high and far higher than I’ve ever seen with my device. While I don’t fully trust low-cost VOC sensors (for the reasons stated above), I, too, would be worried about such high concentrations. Out of curiosity, what happens if you place the device outside (or near enough, such as on a windowsill with an open window)? Do the concentrations decrease significantly as we would expect? With consistent readings this high, I would be suspicious of a faulty or incorrectly calibrated sensor. Another idea is to try multiple rooms around the house and see how the device reacts.

Unfortunately, this is correct. There are some devices out there that could be helpful, but I think it would first be worth looking into whether or not the uHoo is working as expected (which I’m hoping the above tests might help conclude!).

If you have a chance to test the device outside and in a few different rooms, please let me know how you get on!

oBi1 · September 5, 2024, 6:50pm

Blockquote Out of curiosity, what happens if you place the device outside (or near enough, such as on a windowsill with an open window)? Do the concentrations decrease significantly as we would expect? With consistent readings this high, I would be suspicious of a faulty or incorrectly calibrated sensor. Another idea is to try multiple rooms around the house and see how the device reacts.

Hello Ethan, so I ran the tests as you suggested. Interesting outcomes.

Outside placement for some 4 hours:
TVOC - dropped to 36ppb
Living room for 1.5 days
TVOC - during the day - 100-350,
evening (family sitting there, tv) - climbs to 640 (orange section uHoo 400-800)
night - drops again to around 100
Child’s bedroom 1st floor
night - climbs to 960
daytime - 0-100
Back to our bedroom in the attic (3 days)
daytime - 25-150
night - range from 1000 - 4000 at peak climbs up when we both sleep there and then peak in the morning when we get out of bed.
The 4000 was at a night where I deliberately did not use the ventilation system at all. With ventilation running for the first 4 hours of the night at slightly higher than normal speed we reached 500-1000 at peak.

Conclusion to me:
machine seems to function properly
it appears it needed a recalibration as you said
I got nowhere near the extreme numbers as before (though I guess the 4,000 is still very high).
But… this clearly is when people are sleeping in the room at night (both bedrooms saw this pattern).

Tbh - this kinds of puts me to ease. It is clearly associated with humans sleeping. I note too that the CO2 levels rise quite a lot during the night. The ventilation usually counters that but only to around 1500 ppb at peaks (Co2).

Ethan · September 6, 2024, 1:29pm

Hi @oBi1,

Thank you for the update! These readings sound much more reasonable, and I believe the device is working correctly, even if the values still seem a bit high. For the outdoor placement, how near was it to a door and do you live near a busy road/other potential outdoor VOC source? I’m just wondering as the 36 ppb seems a bit high from my experience still, and I’m wondering if leaving it outdoors in a sheltered area for a bit longer could allow for a more complete calibration (as it seems to have some kind of auto calibration on).

This is very true! While minimal, humans do exhale VOCs and over a night in an enclosed space they can build up. I have no idea if they could build up to these levels, but the device is definitely picking up trends properly as the level is expected to increase in an enclosed room with people inside.

This is something I will have to test myself!

Ethan · September 12, 2024, 3:30am

Another, more digestible document on how the Sensirion index for VOCs works:

Tano · November 6, 2024, 9:50am

Hi Ethan, this is my first post here and I want to say how much appreciate your site and forum, they are great, congrats for this amazing job.

Secondly, I did not want to create another topic for this, but I am a similar situation as oBi1, I finished renovating 3 months ago and I still cannot live in my house. All my windows were opened during the summer and I “baked” my apartment for 3 days (left the heat open to around 30gr Celsius for 8 hours)

I read this site inside out but I still have a question: what air monitor should I buy to test the relative VOC variations? I want to put it outside for 1 day, then in various rooms to see what might be the source. I want to put it in each room, then in my new furniture drawers, because they smell the worst. To find out which furniture piece causes these problems.

Should I buy Qingping AQ Monitor? Or AirGadient ONE? In my country I found a portable one, TROTEC BQ16 HCHO, not sure if it’s worth it.

Thank you

Ethan · November 7, 2024, 5:10am

Hi @Tano,

Firstly, thank you so much for your kind words! I appreciate it and am glad you’ve found this website helpful.

Honestly, I feel the AirGradient ONE is the best choice in this situation. I want to be completely transparent and state that I work with AirGradient, but I do feel like it’s the best monitor in this setting. This is primarily because the AG ONE allows you to change the learning duration of the baseline very easily. Being able to adjust this baseline means you won’t need to take the monitor outside every day (although you can still do this if you want to set the baseline learning duration to a shorter period), as you can set it to a 720-hour (30 days) learning duration.

I am a massive fan of Qingping monitors, and they are the monitors that I recommend the most. However, unless there has been a recent update, the learning interval cannot be changed, and you will need to account for the device’s short learning duration.

The Trotec device could be another alternative, but it’s hard to tell without knowing more details about the sensor. I don’t think it’s mentioned in the manual either, so perhaps it could be worth reaching out to them about the matter?

Please let me know if you have any further questions. I am more than happy to help if I can.

Tano · November 7, 2024, 10:48am

Thank you for the nice answer, Ethan.

Your attached picture is great, I finally understood how it works. Unfortunately a longer baseline period for me doesn’t work, because in my city there is a lot of pollution during the night.

Lemme see if I understand correctly: if I buy a Qingping monitor, I have to put it in a clean environment for 24h (I think this is the limit), to set the baseline and then in the room full of VOC? And I have to do this every 24h to reset the baseline?

Thanks a lot again

Ethan · November 10, 2024, 1:40am

In that case, I think both monitors will perform the same, more or less.

Yes, you would want to put it somewhere to set a ‘baseline’. This doesn’t necessarily need to be entirely free of VOCs, but it could be a room that you want to use as a reference to compare other rooms. To fully reset the baseline, you would want to leave it for 12 or 24 hours (I can’t remember exactly which) and then place it in a room. That said, you don’t necessarily need to wait the full 12-24 hours to get a point of comparison, as you will quickly see what a ‘good’ VOC level is even with the relative scale.

It’s also worth noting that you can use ‘absolute’ ppb on the Qingping. While this is a very flawed measurement (for the reasons discussed above), it is probably easier for you to use in your comparisons as it won’t constantly adjust.

SeekingCleanAir · December 9, 2024, 2:58am

Hi Ethan,

Firstly, thank you SO much for sharing all of your knowledge on this topic. I’ve just spent the day reading through your website and I greatly appreciate all of the thorough testing and explanations.

I’m looking for an affordable monitor that can capture data on the following:

particulates (probably at least PM2.5 and PM10)
VOCs
Co2

Context:

Our house was affected by storm damage in early 2022, and subsequent widespread mould after insurance didn’t get started on any remediation or repairs for over 6 months. As a result we lost pretty much all of our contents, and there was also structural damage.
We’ve since had heaps of repairs done (still on-going, hoping to be able to return home in early 2024)
Mould remediation has also been mostly completed.
Painting will start soon. I’ve chosen ultra low VOC paints where we can, but there will be some areas that necessitate higher VOC paints.
We’ll also be having new hybrid flooring installed, which I expect will off-gas for a period of time. (I’m organising with the installer for them to order it a bit earlier and keep it at the store for a time before installing, but I know that won’t fully solve the VOC issue.)
My husband has a respiratory condition + allergies, and I have many chronic medical conditions (including some that make me sensitive to things like VOCs).
So I’d like a VOC monitor to keep an eye on levels. It will help us decide when it’s likely safe for us to move back home, as well as to keep an eye on levels moving forward (as we replace many of our belonging / furniture, since we lost almost everything to the damage from the natural disaster).
I’d also like a Co2 monitor because I’m aware of the impact that high Co2 levels can have on brain function (e.g. while working from home).
And the particulate monitors are helpful for allergy monitoring / prevention.
There is also a STRONG smell in the master bedroom (sharp, kind of plastic-ky, kind of musty) that no one has been able to identify the cause of during the remediation / repairs process. (It doesn’t seem to be mould, as (a) we had extensive mould remediation AND (b) post remediation verification (both tape samples and air samples) showed the remediation was successful. I’m thinking it might be some kind VOC, but we don’t have anything to check the levels with.)

I’ve read many of your articles, so I’m aware that with regards to VOC I’ll likely only end up with something that shows trends rather than perfectly accurate absolutes. I’m okay with that. I just want to have a better understanding of our air quality so that I can do my best to keep us healthy.

I’m in Australia.

Do you have any specific recommendations for my situation? Every time I think I’ve found a good option, I realise it’s missing a feature I might need.

SeekingCleanAir · December 9, 2024, 3:04am

e.g.

Aranet4 or Inkbird have been recommended to me for affordable Co2 monitoring, but they don’t capture VOCs.

Airthings View Plus does PM1, PM2.5, CO2, VOC, temp, and RH - but not PM10 (and since pollen and dust allergies are in play, I think it would be a good idea to be able to capture PM10 info?).

AirGradient ONE offers PM1, PM2.5, PM10, CO2, VOC, NOx, temp, and RH - but only offers a Web Dashboard for connectivity (no app), which might make accessing data, notifications, etc more difficult etc.

Qingping AQM Gen2 offers PM2.5, PM10 CO2, VOC, temp, and RH - but no PM1 (and I’m not sure if that’s one I’ll need or not?)

I just feel like I’m going around in circles!
(And kicking myself that I’ve been sick for the last few weeks and wasn’t able to do this research in time for Black Friday sales!)

Price is definitely a factor: I’m disabled and unable to work, my husband is only able to work part time (splitting his time between working and caring for me), and unfortunately insurance did not cover all the damage to our house / contents. But health is a priority for us, so I’m willing to forgo replacing other contents of our house in order to get something that’s going to give us good information to help our health. I’d much prefer to have clean air and no couch than the other way around!

Ethan · December 9, 2024, 10:50pm

Hi, @SeekingCleanAir (I love the name, by the way!); thank you for joining the forum and for your kind words - I really appreciate them.

From what I can summarise from your points, VOCs are the most important things for you to monitor, but CO2 and PM are also necessary. I’m glad you’ve already read my content on the difficulties with VOC sensors, as that will make this far easier to explain. I am working on a more in-depth article on the issue with VOC sensors for AirGradient’s blog, and I will be happy to share that with you once it’s completed, as it gives a better background than this post does. As to the devices you’re considering:

I agree; skip these as they won’t give you a complete view of your air quality

This one is interesting because I believe you should not worry about the lack of PM10 readings. In theory, yes, you are right. Having PM10 readings would be very helpful for mould and dust, but unfortunately, current low-cost PM sensors are very limited.

Common low-cost PM sensors such as those from Plantower (AirGradient, PurpleAir, etc.), Sensirion (Amazon Smart AQ Monitor, CO2.Click, etc.) and Cubic (Airthings) don’t actually measure PM10. Rather, they measure PM2.5 and estimate the PM10 based on those values. This is simply a limitation of low-cost sensors, and there’s no way to get accurate PM10 readings from a monitor that costs less than tens of thousands of dollars. If you look at the AQ-Spec results below, you can see that monitors have a lot of difficulty with PM10.

This is the same reason why when you look at the PM1, PM2.5 and PM10 readings from most air quality monitors, they will very closely align. PM1 and PM10 are generally interpolated from PM2.5 data, meaning you shouldn’t worry about the lack of PM1 or PM10 on an air quality monitor because I wouldn’t trust the readings even on monitors that measure these particle sizes.

I need to disclose that I now work with AirGradient (I didn’t at the time of writing my reviews), so please keep that in mind.

If an app is important to you, I think you should skip AirGradient. You can put a link to the web app on your home screen, making it feel like an app, but you can’t get notifications or anything directly to your phone - only your email.

Looping back to the PM10 point, I don’t think it’s important, as PM1 is also just estimated.

I totally understand. Health is the most valuable thing we have, but I still don’t think it’s worth spending more than you need to. Luckily, there are some fantastic air quality monitors around at affordable prices these days! Based on everything we’ve discussed, these are my thoughts:

Airthings - this would work for you, as I would advise you not to worry about PM10. With that said, it’s one of the most pricey air quality monitors out there, and I don’t think you need to or should spend this much.

AirGradient ONE - less than half the price of the Airthings monitor if you get the DIY kit (very easy to assemble). It has all the readings you want, but they do sometimes have bugs and issues that still need some ironing out. They also don’t have an app, which is a big downside. With that said, the dashboard is pretty great (although it can feel a bit overwhelming at first).

Now, one feature makes the AirGradient ONE a good choice in your case: you can adjust the VOC baseline calibration period. As you know, VOC readings are relative, and this baseline normally adjusts every 12-24 hours and can’t be changed. This has limited usability, as even within one day, the monitor will begin to think that off-gassing is normal and will account for that in the new baseline. AirGradient allows you to extend this period up to 720 hours (one month), meaning you can retain a baseline and see changes for longer. This would make it much more useful in your case, where VOCs are the primary concern.

Qingping AQM Gen 2 - a really fantastic monitor and my go-to recommendation. It’s the opposite of AirGradient in that this is a very easy-to-use device with an extremely user-friendly app. The device is also beautiful, with a large screen and a nice display.

However, since VOCs are your primary concern, and there are no options to adjust the baseline period for this monitor, I don’t know if this is the best choice for you.

I would recommend either the AirGradient device or the Qingping monitor over (far more expensive) devices like the Airthings.

Please let me know if you have any further questions. I am happy to help!

SeekingCleanAir · December 10, 2024, 12:23am

Hi Ethan,

Thanks so much for your thoughtful reply!

I did some further reading yesterday of your website yesterday (before I saw your reply here) on the way PM amounts are monitored / reported. I now better understand the issues with the PM10 reporting and so won’t be factoring in PM10 monitoring when it comes to device choice.

I did see that screenshot on your website in a few places, but I was unable to fully understand it. (The first four columns are obvious: device photo, device name, price, and PM size. But I don’t fully understand what the next four columns are representing. Device results? Lab test results? Normal reference ranges? Something else? Not knowing what each column represented made it hard to interpret the chart.)

I appreciate your ethical disclosure that you now work with AirGradient. I did notice that disclaimer in a few places on your website (that you weren’t affiliated at the time of writing certain reviews but do work with them now, and that your current working relationship still allows you to be honest in your reviews about the company / devices moving forward). I appreciate the transparency.

Looking at the available options, if the Qingping AQM Gen 2 offered the adjustable VOC baseline, I’d 100% be going with that one. It offers everything I’m looking for in terms of what it monitors, as well as user friendliness, display, app etc.

However, given that VOC is one of my primary concerns, I agree the AirGradient ONE makes more sense. One of the things I’d like to use it for is to determine when it’s safe / healthy for us to move back into the house, after the painting is complete and the new flooring has been laid. The Qingping’s non-adjustable short-timeframe baseline readjustments wouldn’t be particularly helpful for that, since they’d quickly see the high VOC level as normal.

Budget-wise, that’s unfortunate, because I can get the Qingping for around $200 AUD, whereas the AirGradient is $340 AUD for the assembled version.

I do see that there’s a $254 AUD DIY version of the AirGradient, but the fact that that comes with no warranty, testing, or certification makes me a little hesitant. (I do completely understand their reasoning for not warrantying something that has essentially had a random person - the customer - ‘working’ on the unit during assembly.) I’ll have to do a little thinking on whether that’s a risk we can afford to accept.

I do also notice that both AirGradient versions (assembled or DIY) list that they come with “24 months AirGradient data platform”. What happens after that time? Is the data just no longer available? Or do you need to pay a subscription for further access to the platform?

Thanks again for your help. It’s been a steep learning curve! But your website is fantastic and I’ve learned (and am learning) a lot.

SeekingCleanAir · December 10, 2024, 12:48am

Unrelated note:

Just a heads up about a small typo on a few pages of your website.

AirGradient ONE is listed under the “Best Enthusiast” section of the “BreatheSafeAir Awards”, but the device name is misspelled as ‘AirGadient ONE’ (missing the letter r).

Ethan · December 10, 2024, 3:04am

You’re very welcome! I hope it has helped.

In regards to the image, the only columns that really matter in this discussion are the fourth and fifth. I realise I cut off the labels for the columns - sorry about that! The fifth column is the R-squared value for each of the three PM types.

Each of the values in the fifth column shows how well the data for that monitor correlates with reference-grade (very accurate and expensive air quality monitors) equipment. For example, the PurpleAir (PA-I) has a 0.90 - 0.92 R-squared value for PM2.5 (a very strong correlation as it’s near 1. In other words, it’s accurate for PM2.5), but only 0.32 to 0.44 for PM10 (much less accurate as the results are closer to 0 than 1). I’m sorry if this explanation is not great; the takeaway is that in nearly every case, the PM10 accuracy of the monitors is vastly lower than PM2.5 (and PM1).

Could you please send me a link for this? This seems cheaper than I can find the Qingping Gen 2, and I’m worried we might be discussing different monitors.

I understand, and this is a good reason to want the assembled monitor over the kit. However, I can say that if anything is defective when you get the monitor (kit) it will be replaced (I am in charge of that!). However, it’s hard to have an exact policy in place when there’s so much that is out of AirGradient’s control concerning building the monitor. Even if you get the DIY monitor, you won’t be left high and dry if there are any issues.

That said, I do think the Qingping monitor would be a better fit IF they can improve the VOC functionality. I have just sent them an email asking if this is a feature they can look into, and while I don’t know if it’s possible, they are prompt at responding and have fixed issues that community members have pointed out in the past, so I hope for a positive response. I will let you know if there is an update.

Ethan · December 10, 2024, 3:05am

Thank you! I will update this now. I totally overlooked that!

SeekingCleanAir · December 10, 2024, 3:18am

Ah, totally possible that I was looking at a different monitor! I typed the correct one into google, but it seems that some of the search results came up with a similarly named but perhaps slightly different model? Rookie error!

I can see you’re recommending the Qingping Air Quality Monitor Generation 2, whereas the model I was looking at is the SmartAir Qingping Pro 2 Air Quality Monitor.

Here’s a link:
https://www.bsthealth.com.au/smartair-qingping-pro-air-quality-monitor.html?srsltid=AfmBOopMeqjZ0_yzumAxT7yRFfd4uZFT-1ki6OtPUqN-Nil6vtI44_Kk

I’ve just checked and the Qingping Air Quality Monitor Generation 2 (i.e. the correct model!) would cost me $261.55 AUD to import through Amazon.

SeekingCleanAir · December 10, 2024, 3:39am

" For example, the PurpleAir (PA-I) has a 0.90 - 0.92 R-squared value for PM2.5 (a very strong correlation as it’s near 1. In other words, it’s accurate for PM2.5), but only 0.32 to 0.44 for PM10 (much less accurate as the results are closer to 0 than 1)."

Aha, NOW I understand. Thank you for that explanation! The chart makes sense now.

“I can say that if anything is defective when you get the monitor (kit) it will be replaced (I am in charge of that!). However, it’s hard to have an exact policy in place when there’s so much that is out of AirGradient’s control concerning building the monitor. Even if you get the DIY monitor, you won’t be left high and dry if there are any issues.”

Oh wonderful! I feel a lot more confident about ordering the DIY version knowing that. I do like that it’s built with longevity in mind and that the sensors are user-replaceable (as they likely have a shorter lifespan than the other components).

“That said, I do think the Qingping monitor would be a better fit IF they can improve the VOC functionality. I have just sent them an email asking if this is a feature they can look into, and while I don’t know if it’s possible, they are prompt at responding and have fixed issues that community members have pointed out in the past, so I hope for a positive response. I will let you know if there is an update.”

Wow, thanks so much! If that was something that could be fixed by a software adjustment - rather than needing a hardware change - that would be really handy. (But I’m aware that even software adjustments are not always ‘simple’!)

I did miss your answer to this question below:
I do also notice that both AirGradient versions (assembled or DIY) list that they come with “24 months AirGradient data platform”. What happens after that time? Is the data just no longer available? Or do you need to pay a subscription for further access to the platform?

Ethan · December 10, 2024, 8:09pm

Yes, that is right! It’s a bit confusing, unfortunately and I would have been confused by the naming of that second monitor, too. The Qingping Air Quality Monitor Generation 2 is a fantastic device, and that is what I have been discussing here. The Qingping Air Quality Monitor Lite is also great, but it doesn’t have a VOC sensor sadly.

On the topic of Qingping, I’ve already reached out to them regarding adding a customisable baseline adjustment period. They’ve received the request and said they would pass it on to the development team. Unfortunately, I don’t know if it is something that will be added, but I really hope so!

Sorry, I did miss this! You will always have access to the platform regardless of whether you pay or not - that’s important to remember. However, there will be some premium features that are free for the first 12/24 months and will require payment to continue to access after the trial period. These are features such as alarms, notifications, and historical data for months and years (days will be kept on the platform). Basically, the things that are demanding on the AirGradient servers. I think the ongoing cost will be around a couple of dollars per month (around $24 per year).

I’m happy to answer any more questions if you have them!