One of the first air quality monitors I ever reviewed on this website was the Breathe Smart 2 by Breathe Tech. In fact, at the time, I think it was only the second portable monitor I’d ever reviewed and perhaps the fourth or fifth I’d tried overall. I find it hard to believe, but that was all the way back in 2020!
Looking back on the initial review of the Breathe Smart 2, there’s a lot that I would now change. Really, this is a testament to how much of a learning experience running BreatheSafeAir has been and how far I’ve come. While there’s a lot that I would change in the Breathe Smart 2 review if I could go back to it (I no longer have the monitor and it’s discontinued), I can’t.
Fortuitously, however, I’ve been given a second chance. Why? Well, Breathe Tech has since released the BREATHE Air Quality Monitor which it proudly names its Gen 2 device. I’ve seen these devices floating around on Amazon and Reddit a bit over the past year, and I was curious to see how the updated device would fare in my testing. That leads us to today, where my curiosity has finally been sated.
So, let’s dive in. I’ve now been using the BREATHE Air Quality Monitor for around one month, and, over that time, I’ve been able to test it in my office alongside a multitude of other air quality monitors, on the go, and even outdoors thanks to the included battery. All of my thoughts are shared in this article, but if you also want to share yours, I welcome you to comment in the comment section below.
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Contents
Sensor & Accuracy
An air quality monitor is useless if you can’t trust it, so that is where I want to begin this review – with the sensors used and the performance you can expect from them. Upon asking the BREATHE team, and after doing some of my own research, I was able to find out that the sensors used are as follows:
- CO2 – YYS C8 (also sold as the SC8)
- PM1, PM2.5 and PM10 – Proprietary laser-scattering sensor (that looks to be a clone of the Plantower PMS7003)
- Temp and RH – Sensirion SHT30
- TVOC and HCHO – iS-MM-VOCs-4 (MOX sensor)
Apart from the Sensirion temperature and humidity sensor, these are the sensors usually found in the Tuya-based monitors that get white-labelled and sold under many different names. The BREATHE monitor started life on that same platform, but as I’ll discuss in the pricing section, it has been changed quite a bit since then, and that origin isn’t necessarily a bad thing.
Spec-sheet-wise, these sensors all appear to perform within what I would call the ‘industry standard accuracy’ band. The PM sensor is stated as having an accuracy of ± 10ug/m3 under 100 ug/m3, and ± 10% of the reading beyond that – identical to more common sensors like those from Plantower. The CO2 NDIR sensor has a stated accuracy of ± (50 + 5% of reading) which, again, is quite similar to what we see stated for sensors from much more well-known manufacturers. With that said, higher-end sensors like the SenseAir Sunrise and Sensirion SCD41 do provide slightly better stated accuracies.
For the environmental parameters, the story actually improves. The Sensirion SHT30 is a well-known sensor with a stated accuracy of around ± 0.2 °C to ± 0.3 °C and ± 2 % RH, which is a step up from what many monitors in this price range use. Where the story changes slightly is with the TVOC and HCHO sensor, as I’ve been unable to find any further information on this particular sensor and can’t even figure out the manufacturer. But we’ll get to that in a minute.
Therefore, while the CO2, PM and VOC sensors are largely unknown in the west, the accuracy specifications themselves don’t look to be too bad. Of course, these are only manufacturer claims, so I decided to run some comparisons to other monitors that I have access to. Please keep in mind that these are not accuracy tests, as these are not comparisons to reference monitors, and they’re far from scientific.
Rather, these tests help to show us how this monitor performs compared to monitors and sensors that are well understood and that can be used as an indication to see where this monitor fits. If it agrees with them, we know that it is capable of identifying trends and that it at least provides comparable readings to monitors and sensors that do have published accuracy reports and tests. For these comparisons, I used the AirGradient ONE as it’s a very well-researched device with well-documented accuracy and limitations.
Let’s start with CO2, because that is the metric that is easiest to compare since the NDIR S8 in the AirGradient monitor is known to be very accurate, provided it is calibrated correctly. Over the whole time I had these monitors co-located, both provided similar readings and trends were easily identified by both monitors. While there is some difference in the actual values from each reading, this is likely due to calibration differences. On that note, the BREATHE Air Quality Monitor has an automatic baseline calibration (ABC) ‘feature’ that sees the baseline adjust every 24 hours. If you’re using the device in a room that is regularly empty where the carbon dioxide concentration has a chance to drop every day, this isn’t an issue.
Some carbon dioxide sensors and monitors implement autocalibration, a feature that prevents sensor drift (sensors slowly losing accuracy over time) by regularly calibrating the device.
How ABC Works: On a set interval, the sensor will perform ABC (automatic baseline calibration), which sets the lowest carbon dioxide concentration the device has been exposed to as the baseline (typically 400 or 420ppm). This isn’t an issue if a monitor is regularly exposed to ambient air (around 420-430ppm). However, if the device is in a room where CO2 levels do not reach ambient every calibration cycle (typically seven days), it can incorrectly set a baseline, throwing off all readings until the next automatic calibration.
If your monitor regularly goes outside or is in a room that often sees ambient or near ambient CO2 levels, ABC can be very useful. If not, I recommend disabling the feature.
The BREATHE monitor exports in 15-minute resolution which is what causes the interval discrepancy.
However, if the device is located in a room that isn’t left empty for at least a few hours daily, you will likely notice that this monitor begins to deviate from the true concentration. I’m not a big fan of this, and a 24-hour ABC cycle feels very aggressive compared to the 7-day cycle that is more common on similar sensors. I guess the bright side here is that the monitor is portable, and it is quite easy to put it outside for a few minutes to ‘reset’ the sensor. Overall, the CO2 sensor here looks to identify trends well, but be wary of drifting readings depending on where you place it.
The PM1 and PM10 graphs look identical to the PM2.5 graph since these particle concentrations are normally estimated from PM2.5 values.
For PM1, PM2.5 and PM10 we see a similar pattern with the BREATHE Air Quality Monitor closely tracking the AirGradient readings, but with a systematic offset. Since the Plantower sensors used in the AirGradient ONE are known to overestimate in many cases, this isn’t necessarily a bad sign. Once the AirGradient data is corrected (using the factory calibration), it reads slightly lower than the BREATHE monitor. As with most low cost monitors, the readings from both sensors are probably not entirely accurate, but the trends are clearly visible and the BREATHE Air Quality Monitor is more than good enough to let you know when the particle levels are increasing or decreasing and by what amplitude. It’s worth noting also that low cost sensors tend to be able to provide usable PM1 and PM2.5 measurements, but they shouldn’t be trusted for PM10 readings as low cost sensors simply aren’t capable of measuring these larger particles accurately.
TVOC and HCHO are both displayed as ppb (or parts per billion) but I wouldn’t interpret this in any other way than as relative readings. TVOC sensors are notorious for only using relative indexes due to the inherent difficulties of measuring a category with over 1000 gases. While I was able to see increases in the ‘ppb’ reading when I opened nail polish next to the monitor, I have no way to tell exactly how accurate these are. However, the fact that a jump was recorded at all is a positive sign. For HCHO, I don’t currently have any method to test the device, so I can’t speak on this. However, it’s very likely that it acts in much the same way as the VOC readings.
Moving on to the final parameters – temperature and humidity. For this test, I colocated the BREATHE Air Quality Monitor with a lab-calibrated hygrometer. While my office only sits within a narrow band of temperatures, I was impressed by the general accuracy of the device when it comes to temperature. Unfortunately, I can’t say the same for the relative humidity readings, which sat a consistent 6% off the hygrometer. The good news? This offset looked to be very systematic in my testing, and it’s easy enough to deduct a fixed amount from the value you see on the screen or application.
Overall, the BREATHE Air Quality Monitor is a device that I would feel confident trusting to show me the trends in my indoor air quality. It has a decently accurate CO2 sensor, looks to perform well when it comes to PM, and it’s capable of showing TVOC and (I assume) HCHO trends. Temperature is surprisingly accurate around 30 degrees Celsius, and the only metric I would be wary of is the relative humidity reading.
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Design
The design of the device is simple, and oddly reminiscent of something like the AirFanta G2. There’s a likely reason for this, as both devices started out on the same Tuya platform, which I’ll come back to in the pricing section. The current BREATHE monitor uses its own custom enclosure though, which BREATHE Tech tells me was redesigned in part to fit a larger battery and improve battery life. It’s a relatively compact little device that comes in at 3.6 cm x 7.1 cm x 8.4 cm. At 110 grams, it weighs essentially the same as an Aranet4 Home and is about 40% lighter than the iPhone 17. With that said, the 3.6 cm depth makes it significantly less pocketable than your average smartphone.
The front of the device is dominated by a screen which is decently bright and legible. I’ve never had any difficulty viewing this screen indoors, and I’ve actually found it almost too bright at times (such as when I want to check the air quality during the night – you can change the brightness in the app though). Outdoors, the screen is still easily viewable unless you’re in direct sunlight. The aspect that I appreciate the most about a screen this size is that it’s capable of showing you every metric in a single view – something that even far more pricey devices like the Airthings View Plus can’t (or don’t).
While you can see every metric on the screen at all times, you can also scroll through the ‘focus’ metric by pressing the multi-function button on the back of the device. This allows you to see your pollutant of focus in a large number in the centre of the screen, and it also lets you see where that pollutant sits in relation to its specific scale.
By default, the screen will turn off after 30 seconds with no interaction. However, this period can be lengthened or removed entirely via the application. Handily, the front of the device also features a proximity sensor, so you can simply wave your hand in front of the device to turn on the screen. I’ve found the range to be around 10 cm, so you do need to wave right in front of the device for the screen to turn on. All things considered, this is sensible, since a longer range would make accidental activation easy.
The device has a rounded design with rounded corners and a rounded back which makes it quite pleasant to hold. Despite not being a portable monitor (at least, it’s not intended to be), this device is actually far more comfortable to hold than many dedicated portable monitors like the Aranet4 Home or INKBIRD IAM-T1. Of course, it comes with the downside of being less pocketable than both. Battery life is six hours maximum, with this being extendable if you’re only taking spot readings and then turning off the device in between. In my mind, this isn’t a portable monitor, but rather a monitor with a battery that allows you to move it around your home or take it on a short trip without losing data.
On the back of the device you have the only other design aspects worth noting. At the top, surrounded almost entirely by vent holes is the multi-function button. This button lets you power on and off the device, force a sensor calibration, disable and enable the alarm, switch the focus pollutant on the display, and also allows you to enable Wi-Fi pairing. All of these are done by different button press combinations. Below the vents is a sticker with regulatory information and then a Type-C port for charging. This port supports both A to C and C to C.
There’s really not too much more that can be said about the device’s design, and I’m left feeling content. It’s simple, but it has a decent screen for stationary use while also having a nice feeling while being held. I’m happy with the support for C to C charging (though I firmly believe this should have been standard many years ago), and I’m pleased with the screen size and resolution that is able to comfortably display every metric I might want to see simultaneously.
Application & Connectivity
The BREATHE Air Quality Monitor connects via Bluetooth to your phone running the Breathe Tech application for an initial setup process. During this process, you will be asked to enter WiFi details (2.4 GHz only), and the device will then connect to your network and upload data continuously via WiFi. Generally speaking, WiFi is the better connectivity option as it’s more stable than Bluetooth and the range is usually far superior in a house. The caveat is, of course, that if you don’t have WiFi connectivity (for example, if you take the device with you in the car or to the mall), you can’t sync data with your phone. Luckily, the screen can still show you anything you might want to know!
This connectivity choice again reinforces my belief that this is a stationary monitor first, and that while it can be used somewhat portably, it’s not supposed to be used in a situation where you might use an Atmotube Pro 2 or AirBeam. Those are dedicated portable monitors, whereas this is an indoor monitor with a battery backup. In this way, it’s very similar to the Qingping Air Quality Monitor Lite and Qingping Air Quality Monitor Gen 2.
Once you’ve added your device via the application, you will be met with a ‘Home’ screen which acts as your device management screen. If you have multiple devices, it’s this screen that allows you to access the individual data and settings for each device. You can also sort them by room, hide specific monitors, reorder them, and, of course, rename them. There are settings on a ‘Home’ level that also allow you to share access with others. This is quite a standard (but by no means bad) app format that other companies like Qingping also use.
By tapping into a given monitor, you will be presented with the current readings of every parameter and a historical graph. The graph shows 24-hour periods by default, and you can scroll to previous days. The application will allow you to view up to 90 days of historical data, which is stored in the cloud. One interesting note here is that you cannot view any historical data for temperature and humidity. In my mind, this is a bit of a miss, as it’s likely a very easy thing to add to the application and the data is clearly already being collected.
From the device screen, you can also access settings specific to that given BREATHE Air Quality Monitor. Here is a complete list of the user-adjustable settings:
- Alarm Active (on/off)
- Alarm Volume (Mute/Low/Medium/High)
- Alarm Ringtone (Ringtone 1 – 4)
- CO2 Alarm Level (600 – 1600 ppm)
- PM2.5 Alarm Level (16 – 66 ug/m3)
- Screen Sleep (on/off)
- Screen Sleep Delay (10 seconds – 300 seconds)
- Screen Brightness (0 % – 100 %)
- Temperature Unit (C/F)
- Export Data (Single day, Date Range, All Data)
There are a few things worth noting here. Firstly, I appreciate having user-adjustable alarm levels and the flexibility that I have over how the screen functions and looks. On the other hand, some of the alarm levels seem a bit arbitrary. Personally, I’d like to be able to have my PM2.5 alarm go off at maybe 5 ug/m3, as that’s what I consider my maximum allowed level indoors. For CO2, the 1600 ppm limit also seems a bit odd. I don’t see these as big issues, but they are somewhat surprising.
What I do like is the range of data export options, which allow you to receive a .CSV file via email. For anyone like me, this is a key feature on any air quality monitor, as graphing data on a larger screen and over a longer period is the best way to identify trends and the steps required to address them. Regardless of which period you choose to export, the data comes through in 15-minute resolution.
There is also a second settings menu for the device which is accessible via the pencil icon in the top-right corner. This is generally for more admin-level management, and it’s where you can group the monitors, check network settings, and share the device with other users. There are two features here that stood out to me – the ability to set an alternate network, and the offline notification setting. Of particular note is the alternate network setting, which allows you to specify a second WiFi network for the device to connect to in the absence of the first.
While the intention of this is clearly for reliability, it has some other (cooler) use cases, such as allowing you to set a WiFi network at your workplace or school as the ‘alternative’. Once you leave the house, the local network will be dropped, but it will be able to reconnect once you reach your destination if you have that second network set as the alternative. Potentially quite a cool feature for some!
There are also some app-wide settings such as dark mode, app notifications, personal information, app-wide unit settings and more. However, these settings are a lot less interesting than the device-specific settings and more in line with what you would expect to encounter in such an app.
Pricing & Competition
By this point, we’ve established that the device is decent. It has comparably accurate sensors to other devices in this price range, and the connectivity and application are solid if not good. However, this doesn’t matter if the device is poorly priced, so let’s discuss that.
I’ve mentioned a few times in this article that the BREATHE Air Quality Monitor started out as a white-labelled Tuya monitor, and the number of very similar-looking devices on AliExpress supports that. However, it’s no longer just a rebadged product and BREATHE Tech has modified both the hardware and the software over time, with a custom enclosure, changes to the internal sensors, and its own (much better) app.
A quick search of AliExpress shows a range of similar-looking monitors that cost around $140 – $160. The AirFanta G2, which I also believe to be a white-labelled (and, comparatively, unmodified monitor), is currently $99, but that lacks the VOC and HCHO sensors. The BREATHE Air Quality Monitor? Its normal price is $119.99 on Amazon or $129.99 on the official website, but it’s regularly on sale for $99. There is also bulk pricing, that allows you to purchase two devices for $199 and three devices for $289 total. Furthermore, you’re getting a 2-year warranty and direct customer support with this monitor.
At this price, it’s quite a compelling deal, and that’s before you consider the application, which I think is far better than the Tuya app that these other devices usually use. With that said, there are also other options in this price range, such as the Qingping Air Monitor Lite, and a few that sit at around $130, such as the AirGradient ONE (kit). Both of these provide alternatives that have strengths and weaknesses in other areas.
If you want the most depth and advanced features in an air quality monitor, something like the AirGradient is a better choice. If you want a cheaper device with equally good connectivity and more third-party accuracy results, the Qingping is a good choice. However, if you want a monitor that is solid when it comes to parameters covered, connectivity, and design, and even has an internal battery (albeit with a short battery life), the BREATHE Air Quality Monitor is worth considering.
Conclusion
So, is the BREATHE Air Quality Monitor worth your money? Well, depending on what you’re looking for, it’s definitely worth considering. While it’s not as advanced as some monitors and doesn’t have the third-party validation of others, it’s a well-rounded monitor at a reasonable price.
It’s capable of showing surprisingly good temperature readings, and it can easily show trends in CO2 and PM levels. It has solid connectivity (just keep in mind it’s WiFi, not Bluetooth), an application with all of the essential features, and even a decent data retention period.
However, keep in mind that the relative humidity readings appear to systematically underreport, and both the tVOC and HCHO ‘absolute’ readings should only be used to identify trends. Again, this is an issue with all low-cost monitors and isn’t something that’s limited to the BREATHE monitor.
While I was only able to test a single monitor, the fact that the application looks to handle multiple monitors and rooms within a house is also interesting. For anyone looking to cover multiple rooms with devices, this could also be a decent option.
If you’ve tried the BREATHE Air Quality Monitor, or if you have any questions remaining after reading this article, please don’t hesitate to leave a comment below! I try my best to reply to everything. Thank you for reading!
- Every metric is visible on a single screen, something even far pricier monitors can’t do.
- CO2 and PM readings tracked my AirGradient ONE closely, and trends are easy to identify.
- Flexible CSV data export via email, with 90 days of history stored in the cloud.
- The internal battery makes it easy to move between rooms without losing data.
- Compelling price for the parameters covered, especially at the regular $99 sale price.
- Relative humidity readings sat a consistent 6% low in my testing.
- The aggressive 24-hour CO2 auto-calibration can cause drift in rooms that are regularly occupied.
- No historical data for temperature and humidity in the app.
- Battery life is only around six hours.
- TVOC and HCHO readings are only useful for identifying trends, not absolute values.
BREATHE Air Quality Monitor FAQ
Is the BREATHE Air Quality Monitor portable?
Not really, and I don’t think it’s intended to be. It does have an internal battery, but you’re looking at around six hours at most, and the 3.6 cm depth means it’s nowhere near as pocketable as something like the Aranet4 Home. In my mind, it’s best thought of as an indoor monitor that you can move between rooms or take on a short trip without losing data. If you want a dedicated portable monitor, the Atmotube Pro 2 or AirBeam are far better suited.
Does it need WiFi to work?
For syncing data with the app, yes. Bluetooth is only used during the initial setup, after which the device connects to your 2.4 GHz WiFi network and uploads data from there. If you’re away from WiFi, the screen will still show you every reading, but nothing will sync until you’re back on a network. Handily, you can also set an alternate WiFi network in the app, so the device can reconnect at a second location such as a workplace.
Can I export the data?
Yes, and this is one of the features I appreciate the most. From the device settings, you can export a single day, a date range, or all data, and you’ll receive a .CSV file via email. Regardless of which period you choose, the data comes through in 15-minute resolution. The app itself stores 90 days of history in the cloud, though (oddly) it doesn’t show any historical data for temperature and humidity.
How accurate are the sensors?
Reasonably, with a few caveats. The temperature readings were surprisingly good, and the CO2 and PM readings are perfectly capable of showing trends. However, the relative humidity readings appear to systematically underreport, and the tVOC and HCHO readings should only be used to identify trends rather than as absolute values. To be fair, that last point applies to pretty much every low-cost monitor, so it’s not something that’s specific to the BREATHE monitor.
Is it worth it at $99?
If you want a well-rounded monitor with a good screen, solid connectivity, and an app that covers all of the essentials, I think it is. It’s regularly on sale for $99 (its normal price is $119.99 on Amazon or $129.99 on the official website), which puts it in the same range as the Qingping Air Quality Monitor Lite and not far off the AirGradient ONE kit. If you want more advanced features, go for the AirGradient. If you want more third-party accuracy results, go for the Qingping. Otherwise, the BREATHE Air Quality Monitor is a solid option.
