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Breathe Smart 2 Portable PM2.5 Monitor Review

The Breathe Smart 2 is a portable air PM 2.5 monitor from the company Breathe Tech LTD. The company, based in London, looked to create a portable air quality monitor that is not only functional but also practical. 

The product aims to solve two issues – to be small and pocketable enough so as to be easily portable, and to not have to rely on an app for quick air quality readings and data. As someone with experience with portable air quality monitors, the lack of app reliance on the Breathe Smart 2 air quality monitor instantly stood out to me.

In this review, I want to take an in-depth look at the Breathe Smart 2 air quality monitor from Breathe Tech. I will cover all aspects of the monitor from the sensors to the design, battery life and more. If you have also tried the device, I would love to hear your experiences in the comments.

This post contains affiliate links. For more information, please refer to my affiliate disclaimer. I was sent a product for review, but the article is not sponsored. All opinions expressed in this post are my honest thoughts. I only recommend products that I genuinely believe in.

Information on this blog is for informational purposes only. Readers are encouraged to confirm the information herein with other sources. Furthermore, this information is not intended to replace medical advice from professionals. This website assumes no responsibility for the accuracy of the information, and information is subject to change without notice. Devices mentioned on this website are not medical devices and do not guarantee protection.


Breathe Tech PM2.5 Monitor

The Breathe Smart 2 air pollution monitor uses a Plantower sensor to detect PM2.5 particles in the air that enters the device. The device has two grills, one on either side. Air is pulled in through one set of grills with a fan (which is not audible unless placed right up against your ear) and expelled through the grill on the opposite side.

In the middle of these grills is the Plantower laser PM2.5 sensor. This sensor uses a laser to detect when particles enter the device. From this information, the PM2.5 concentration can be established.

One of the most important factors when it comes to air quality monitors is the accuracy. Usually, these devices are semi-accurate. This means that they are capable of providing an overview of the air quality, and they can detect concentration changes in pollutants. At the same time, they can vary a bit and the exact readings often vary within 15-20%.

The Breathe Smart 2 falls in the same category. Research has been done on different Plantower sensors (Journal of Sensors, AAQR, and these reports indicate that these sensors are good at providing information on local air quality. While there may be some slight deviation in results, the device is more than capable at giving a relatively accurate reading on the air quality and reporting air quality trends and spikes.

While by no means a scientific test, I compared the device to my personal indoor air pollution monitor, the uHoo air quality monitor. Interestingly, both devices reported very similar concentrations and their overall trends were identical.

The sensor has an effective range of 0-500 μg/m³ with a maximum range of 0-1000 μg/m³. The device is most accurate with particles above 0.5 μm, and the specified accuracy for these particles is greater than 98%. On top of this, the device is rated to work between -10 and 60 degrees Celsius and 0-99% humidity.

Purchase Breathe Smart 2 air quality monitor.

Data & Reporting

Breathe Tech Air Pollution Data

The Breathe Smart 2 PM2.5 monitor is a standalone device and as such, it does not offer a feature for data exporting – in fact, it doesn’t even have any wireless connectivity due to this. However, the device itself is capable of displaying either a graph or a table of the past air quality (up to a maximum of 30 days).

There is a screen on the front of the device and this screen is how you will control the device. The air quality reading is very easy to read and the UI is very clear. You can either set the device to report on PM2.5 concentration or to report AQI. Personally, I set it to PM2.5 as this is of more interest to me.

There is a circle with a number in the middle. The circle indicates where your concentration is in regards to the AQI, and the number in the centre reflects the exact number. The number and text will also change colour depending on the air quality.

The device will alternate between this reading and advice. At times, the device will show some kind of prompt – just now it told me ‘Air quality is good, no action required’. Both this advice and the reading are very simple, but they do the job and I appreciate the simplicity that the device is designed around.

Interestingly, the device also shows a BREATHE|Score. This score is designed by Breathe Tech and it provides an ongoing reading between 0-100. The reading starts at 50 and will either go up or down based on your PM2.5 concentrations. I appreciate this small addition as in a slight way, it gamifies improving your air pollution exposure – I want to get that 100 score!

Overall, the data provided by the Breathe Smart 2 is solid. The device provides a basic reading of the local air particle pollution and doesn’t do much more. Many people will appreciate this as the device provides only the information that it needs to – it also does this without the need of any companion app/device.

I do wish that data could be exported as a spread sheet, though. It’s much easier to see trends on a bigger screen, and the device wouldn’t need to make many sacrifices to its design philosophy as the data could be imported through the USB-C connection on the device.

Purchase Breathe Smart 2 air quality monitor.


Breathe Smart 2 PM2.5 Monitor

One of the biggest strengths of the Breathe Smart 2 is its design. While the overall design is good, I believe that three specific factors of the device excel. These factors are the size, simplicity, and the display.

To begin with, the size of the product is very small. It’s very easily palmable and the Breathe Smart 2 is significantly smaller than both the Flow 2 and Atmotube Pro. While both of these devices offer a more diverse range of pollutant measurements, the size of the Breathe Smart 2 makes it very attractive. 

On top of this, the device is totally silent unless placed right up against your ears. While other portable monitors that I have tried are relatively silent, they do make audible noises when taking measurements meaning that they aren’t ideal when docked indoors. 

Secondly, the Breathe Smart 2 is very simple. All data is managed on the device, and there is no app or bluetooth connection needed. However, where the device truly excels is in its UI. The UI of the device has relatively few options, but everything is very quick and easy to access. 

Personal PM2.5 Monitor

The UI is navigated by using a small touchscreen on the front of the device. Below the screen is a single, round button which acts as a back button. The touchscreen is very responsive and I was impressed by how fast the Breathe Smart 2 reacted to touches and presses of the button – it’s fast, responsive, and I never noticed a delay when navigating the menus.

To follow on from the point of simplicity, the device also feature two LED strips on either side of the device. These strips change colour based on the local air quality based on the air quality index. These LEDs are always on, and they allow for a very quick way to check the local air quality. 

On the Breathe Tech website, it is stated that Chris (the company founder) aimed to make the device a standalone product. Nearly every other portable air pollution product on the market relies on a paired phone to assist in visualizing the data from the device. The Breathe Smart 2 takes a different approach, and everything is handled on the device. 

The device features a clip on the back of it, allowing for it to easily attach to a variety of different materials. The clip is quite small, and it’s best used for attaching the device to clothes or a backpack. However, also included in the box is a longer velcro-strap. Using this strap, you can attach the Breathe Smart 2 to anything from bike handlebars to a bag strap.

Purchase Breathe Smart 2 air quality monitor.

Battery & Charging

Breathe Smart USB Dock

The Breathe Smart 2 features a USB-C port at the bottom of the device and it also comes with a USB-C charging dock. This design reminds me a lot of the Flow 2 portable air pollution monitor, and the inclusion of a dock is a great choice. Rather than the device simply being a portable monitor, the dock also allows the device to be an indoor air pollution monitor when needed.

The device does feature a battery, however, the battery life isn’t great. The battery lasts up to eight hours, but I found it to be shorter at times. Keep in mind, that this battery life is with quite heavy use and with everything on (screen at all times and LED light strips on). If put on night mode, the device might last a bit longer.

This short battery life isn’t ideal, but I can understand. The device takes readings every second, and there is a constant fan running inside the device. The device is also quick to charge, and it’s easy to get a few more hours out of the battery after a short charge.

In saying this, I do wish that we could turn down the concentration-reading frequency to save battery life. For example, it would be great to see a choice to take a reading every second, 10 seconds, 30 seconds, 1 minute, etc. Then the user could choose between battery life or constant updates.

Purchase Breathe Smart 2 air quality monitor.

Other Features

Breathe Tech Breathe Score

Before concluding this review, there are a few other features that are worth mentioning about the device. First among these, are the supported languages. The device currently supports English, French, Dutch, Spanish and Italian.

The Breathe Smart 2 also features an alert system, as it has speakers built in. I generally don’t use the alert system, and you don’t need to enable it. However, if you do want an audible warning when the PM2.5 concentrations reach a certain level, you can enable this. The volume of the alarm can also be changed.

Triple-tapping the back button will enable night mode. Night mode will instantly dim the device’s screen, disable audio alerts, and will also disable the LED strips on the side of the device. I appreciate how easy it is to turn night mode on and off, and it’s much easier than needing to navigate through a settings menu!

Purchase Breathe Smart 2 air quality monitor.

Is the Breathe Smart 2 Worth It?

Breathe Tech Air Monitor

Overall, I found that the Breathe Smart 2 device does what it advertises very well. The device is a great standalone product, and it provides some of the most accurate PM2.5 readings I have seen in a portable air quality monitor.

On top of this, the device is very responsive and simple to use with its great touchscreen UI. It comes with a charging dock that allows it to be both a portable air quality monitor and an indoor air quality monitor. In both of these situations, it is more than capable of showing trends in fine particle pollution.

I do wish for a few things with future iterations of the device, however. Firstly, I wish there was a way to export data without sacrificing the standalone functionality (data exporting via the included USB-C cable). My biggest wish, though, is for the user to be able to control how often a reading is taken.

Right now the biggest issue with the device is battery life. If the user could set the fan/sensor to only power on once every 30 seconds or once per minute I can’t help but feel like the user would still get the data they need while also having a much better battery life. Of course, for anyone needing constant updates a once per second reading would also be an option.

Overall, the Breathe Smart 2 is a great device for anyone looking for updates on their local air pollution. If you are someone that is especially sensitive to air quality changes, having a device like this can let you know which areas to avoid, where to wear a mask, and where you can breathe freely.

Purchase Breathe Smart 2 air quality monitor.

Breathe Smart 2 FAQ

What Does the Breathe Smart 2 Monitor?

The Breathe Smart 2 air quality monitor monitors the local PM2.5 particle levels.

Is the Breathe Smart 2 Accurate?

From testing, the sensor in the device is accurate to 98% on particles > 0.5μm. Smaller particle readings are less accurate, with the accuracy for particles under 0.3μm being accurate to 50%.

What Is the Breathe Smart 2 Battery Life Like?

The battery life of the device is around 6-8 hours. Charging the device back to full seems to take around an hour.

Does the Breathe Smart 2 Need a Phone/App?

No! The biggest strength of the Breathe Smart 2 device is that it is a standalone product. This means that there is no companion app and no need for a smartphone.

Where Can I Buy the Breathe Smart 2?

You can purchase the Breathe Smart 2 on Amazon. You can also purchase it from the Breathe Tech website.

How Big Is the Breathe Smart 2?

The Breathe Smart 2 is quite a small device. It is 70mm tall, 46mm wide and 27mm thick. The device is very easy to hold, and it can easily be attached to a bike or backpack.

Read 8 Comments on 'Breathe Smart 2 Portable PM2.5 Monitor Review'

  1. I purchased a Breath/Smart 2 Mod. BTL-20001 in April of 21. Last week it stopped working.
    Is there a battery that must be replaced, or is it expensive junk at this point.

      1. Sorry to hear that from both of you. My device is still working, but the fact that both of yours have suddenly died is a big concern. Have you tried reaching out to the company?

  2. I purchased mine in February 2021 and it has now failed – The screen is now blank and does not power on either from the docking station or directly connected to the lead. Power was tested ok so it is the unit, suspect the battery is not fit for purpose and has a short life span although not sure how you get into the unit to test. I would recommend to absolutely not purchase this item or any item from this company, however a bit of a fruitless warning as it looks as though the whole company is in trouble and there are no longer any products available on their web site.
    Although maybe obtained circa 2 years of on/off usage, I would consider this to be 98.10 GBP down the drain

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