Skip to content

Flow 2 Review – Air Pollution Monitor

Air pollution is one of the most harmful hidden dangers in the modern world. With more and more health conditions being linked to it every day, it’s important to be aware of the air pollution around you. 

If you are aware of the dangers of air pollution then you are one step closer to being able to act accordingly. However, one more step is required – how can we monitor the air pollution that we expose ourselves to? 

That is where the Flow 2 by Plume Labs comes in. The Flow 2 is the second model of a portable air quality monitor that has recently been released. This monitor can go everywhere with you and it will allow you to see exactly what the pollution is like as well as the composition of the air. 

On a greater scale though, Flow 2 also allows you to become aware of trends, dangers, and other aspects which are just as important to know. For example, Flow 2 can allow you to identify areas where pollution is greater (or less) which can, in turn, allow you to plan around those areas. 

Wondering about which portable air quality monitor is the best? Check out my Flow 2 vs Atmotube Pro comparison. The Breathe Smart 2 PM2.5 monitor is also a good option for particle pollution.

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.

What Is Flow 2 by Plume labs?

Flow 2

I have reviewed quite a few air pollution monitoring devices thus far on this blog. However, none of them is quite like Flow. Some of them are indoor air quality monitors such as the uHoo, and some are partly portable such as the Laser Egg

But this is where the Flow differs. Where those devices are meant to be placed somewhere indoors and to be left alone, this device is the total opposite. It is built to be portable, and it is built to travel with you when you go outdoors. 

Of course, that isn’t to say that the Flow can’t be used as an indoor air quality monitor – it can, especially with the fantastic dock that is included. However, you can instantly tell that it is intended to be strapped to a bag or a bike and taken on your journeys with you. 

The mapping functionality within the app further enforces this – the Flow 2 is meant to be a portable air quality monitor that you can take everywhere with you and that will monitor the air quality and let you answer that question that I always get asked, ‘when do I need to wear a mask?’.

In short, Flow 2 is a device that is meant to provide you with a portable air quality monitoring solution. Wherever you go, you will be able to monitor the air quality and this has a large number of implications. It can allow you to plan the best jogging path, let you know when you need to wear a mask, or even greater, it can let you know if a certain area is safe to move to. 

Purchase Flow 2 by Plume Labs here!

Why Do You Need the Flow 2? 

Flow 2 AQI Monitor

I can foresee some people asking the question ‘why should I get such a device? I can just check the AQI on my phone’. I want to answer this question before proceeding further with this review. 

While it is true that there is a multitude of fantastic apps out there for monitoring the air quality, there are big limitations on those apps. Firstly, they are limited by sensors. If you live in a big city (such as Seoul), this is no issue. 

However, many smaller cities and towns lack air quality monitoring tools, and these apps won’t work without a data station to retrieve information from. 

Further than this, while these sensors are great, they are also limited. Air quality isn’t uniform within an area, despite what these monitors would have you believe. Let me give you an example. 

I live in Seoul, and in Seoul there are many districts. If I take the air quality reading for one of these districts, let’s say Dongdaemun, I can see an overall AQI. However, that AQI is taken at one single point in Dongdaemun. It doesn’t necessarily reflect the actual AQI of the air that I am breathing. 

Flow Air Monitor

For example, areas near motorways are often more polluted. The same goes for areas that are impacted less by the wind. Flow 2 provides the advantage of being able to identify the air quality on a far smaller scale – I can identify air quality differences from street to street with it. 

This is ideal for anyone looking to plan an exercise path (for biking, jogging, walking, etc), or even for finding out if a certain street is a good place to live. The Flow will allow you to see the exact air quality in your vicinity – rather than just the air quality within the district or city you are in. 

Smart air air purifier review – the most cost-effective air purifier there is!


Flow 2 Air Pollution Monitor

As mentioned previously, the Flow 2 is the second device in the Flow series. If you are unfamiliar with the original Flow, I recommend reading about its features.

Over the original device, the second version offers a few benefits. It offers increased accuracy (as well as PM1 measurement), increased battery life and management and data exporting. 

Obviously, increased accuracy is always welcomed, and the addition of PM1 is also a very welcome addition. PM1 is actually recognised as being more harmful than PM2.5 which is, in turn, more harmful than PM10. Therefore, allowing for PM1 measurements is a fantastic addition to the Flow. 

The battery life has also been expanded to around 3 days. However, it’s important to note that the overall battery life is around the same as the original model. The extra battery life comes from the fact that the Flow 2 supports an idle feature that allows you to put it in a sleep state for a set amount of time. This is great for when you are sleeping or don’t need to monitor the air quality. 

Thirdly, and perhaps biggest, is the ability that the Flow 2 has to export data. While this may not sound particularly useful at first glance, it is a very big benefit. The ability to export data allows you to submit air quality data to organisations, but also to monitor and graph the trends on proper software such as Excel. 

Flow 2 Data Export

Other than these features, the Flow 2 also offers some of the best air quality sensors in the market in a very small package that is also very stylish. The device can easily fit in on any bag, and the design is actually rather eye-catching. 

If you are serious about air quality this feature is a great addition. 

Overall, the Flow 2 is definitely an improvement over its predecessor. While a lot of the best aspects remain the same, there are also many improvements that make the second iteration a good upgrade. 

Craft Cadence Nanofiber Mask full review.

Functionality & Accuracy

Flow Air Data

I must begin by stating that I have no lab calibrated air monitor to compare to. Therefore, while I can state my experiences and compare to other AQI monitors, I can’t state whether or not the device is totally accurate. 

In saying that, I did find the Flow 2 to give similar readings to my other air quality monitors (and the official Seoul air quality monitors) in all readings except for PM1, as PM1 is not a common particle size that is measured and so far the Flow is the only device that I have found to measure it. 

Flow 2 measures 5 different pollutants. Three of these are fine particles (PM1, PM2.5 and PM10), and the other two are nitrogen dioxide and VOCs (volatile organic compounds). This is a solid group of measurements, especially considering that fine particles such as PM2.5 are some of the most dangerous.

Although I have no devices to compare the Flow to for PM1, I found the other readings to usually be within a close range of the other air quality monitors that I have. I also found that when standing next to official air quality monitors in Seoul (I tested two) that the readings were within 10% of the official monitors. This is similar to what Plume Labs claims on their website.

When lab tested, the Flow 2 was found to be accurate within 5% for nitrogen dioxide, within 1% for VOCs and around 10% for PM1 and PM2.5. PM10 readings were found to have 83% correlation to the reference device. This means that overall the device is accurate to within 10%, with the exception of PM10 readings which can differ more.

It is important to also remember that AQI is not one overall global standard. Rather, many different countries use their own AQI ratings which differ in pollutants considered and concentrations. The Flow 2 uses the Plume AQI. For this reason, you may find that the Flow provides different AQI readings than other devices or apps that you use.

The Plume Labs AQI system is based on internationally recognised exposure guidelines as set by the WHO. Where WHO guidelines were not available, other data sources were used.

  • The European Commission
  • The American Environmental Protection Agency (EPA)
  • The Chinese Air Quality Standards
  • The French legislation regarding Air Quality
Plume Labs AQI

Plume Labs AQI reading. Data taken from Plume Labs.

If you want consistency across AQI readings, I recommend using the Plume Labs AQI app to keep an eye on the AQI. This will help minimise confusion that can be caused due to different AQI readings in the same conditions.

This leads me to say that I believe the Flow 2 to provide accurate data regarding the air quality. While it can differ from the official readings at times, these differences are generally very minor and they won’t impact the end result. 

Purchase Flow 2 by Plume Labs here!


Flow 2 Review

The Flow 2 features connectivity to both IOS and Android phones via a Bluetooth connection. This connection is actually one of the most stable that I have ever used, and every time I opened the app (even after the Flow battery had died) the device was connected and ready to go.

The device also maps your position by using GPS data from your phone. Using this data, the device is able to create a map showing the air pollution in each point along your journey. 

Cable-wise, the Flow 2 is also very modern and features a USB-C connection in the bottom of the device. This connection is very future-proof, and as more and more devices support USB-C this will become increasingly relevant.

The Flow 2 also features a USB-C powered dock, and this dock is one of the best I have ever experienced. Although small, it is also very weighty and feels of very good quality. Using the dock allows for quick charging via two metal contacts in the bottom of the Flow 2 device. 

Another connectivity aspect that I greatly appreciated with the Flow 2 is the capability to update through the app. When an update (for the device) is available, a red dot will show on the ‘update’ icon in the app. To update, simply tap on this icon and wait for the process to finish!

Flow 2 Update Process

Overall, the Flow 2 is very connected and it follows all of the most modern standards for connections. It definitely is not lacking in this department!


Flow 2 Design

The design that Plume Labs has created is another area in which the Flow excels. Not only is the device small and inconspicuous, but at the same time, when it does draw attention it is sure to impress. 

The design features many small holes, all of these also double as functional, allowing the device to get a 360 degree reading on the air quality. 

The device features a USB C port as well as two metal contacts at the bottom. The USB C port allows for direct charging (which is especially useful on the go), while the two contacts allow for wireless charging via the included dock.

On top of the Flow you can find a plastic strap. This strap features three holes, allowing for you to choose exactly how large you want the loop to be. Further, this strap feels of good quality and despite being plastic, I can imagine it lasting for a long time.

A touch sensitive button and light array can also be found on the front of the device. These lights indicate factors such as charge levels, battery, and the colour of the circle lights represents the AQI (green, yellow, red, purple).

It is worth noting however, that due to the many holes in the device required for allowing air through, that the Flow 2 is not water proof and can be damaged by water. Therefore, it is important to protect it from rain. Luckily, rain cleans the air and during these times the air quality should be far better than normal!

Flow 2 App

Plume Labs Flow 2 App

At the heart of the Flow device is the app. Since no data can be read from the device itself, the app will be how you can access the data from the device and how you can map your neighbourhood. 

Luckily then, the app is one of the better air quality apps that I have tested. Plume Labs has always made decent apps, and the Flow application is no exception. While simple, the app lets you quickly access all of the data that you might need. 

However, the app won’t provide you with the full details. For this, you will need to export the data and open it in some form of graphing software. While the app does allow you to map the data, the best views will come from exporting. 

The app will allow you to measure each of the five supported readings as well as to see the overall AQI.

Is Flow 2 Worth it?

Flow 2 Outdoors

Overall, I have been pleasantly surprised by the Flow 2. Despite being one of the lower priced air pollution monitors on the market, this device provides accurate readings in an easy to understand format. 

The device also features all of the most modern connections and is the only air pollution device that I have tested this far to do so. While this may not matter for many people, it was a big deal for me. Being able to have all of my devices using the same connection (USB C) is something that I dream of. 

Even further though, I believe that the Flow is a great device to allow individuals to monitor the impact of air pollution on their personal lives. While it’s easy to distance ourselves from air pollution and to believe that it doesn’t impact us… Well, it does.

The flow allows you to monitor air pollution not only in your local area, but within your direct vicinity. This has a multitude of real life applications and it makes the Flow a unique device among other air pollution monitors. 


  • The Flow 2 is one of the few affordable portable air quality monitors on the market.
  • AQI readings are accurate within 10% and usually within 5%.
  • Fantastic connectivity options that provide a stable connection.
  • App is clean, functional, and fast.
  • The Flow 2 is elegantly designed and the strap allows for easy attachment to bags, bikes, and other devices.
  • Decent battery life, especially for such a small device.


  • GPS functionality is linked to your phone. While I understand why the GPS functionality is tied to the smartphone, it means that you must always have your phone on you.
  • Battery life can be hard to manage. Since the idle function requires manual input, it can be hard to always remember. It would be nice to have some kind of functionality that allows the device to recognise when it’s not in use.

Purchase Flow 2 by Plume Labs here!

Flow 2 FAQ

How Is Flow 2 Better than Flow?

Flow 2 features a new PM1.0 sensor, greater accuracy, battery management (you can disable recording for set periods of time to maintain batter), and the ability to export data.

Is Flow 2 Accurate?

When lab tested, the Flow 2 was found to be accurate within 5% for nitrogen dioxide, within 1% for VOCs and around 10% for PM1 and PM2.5. PM10 readings were found to have 83% correlation to the reference device. This means that overall the device is accurate to within 10%, with the exception of PM10 readings which can differ more.

Are There Any Flow 2 Alternatives?

There are a few other devices out there that function similarly to the Flow 2. The most popular is the Atmotube Pro.

Do I Need an Air Quality Monitor?

Not everyone needs an air quality monitor. However, the truth is that air pollution is a major issue and something that everyone should be aware of. A device like the Flow 2 allows you to identify the quality of the local air that you are breathing – local air quality varies a lot, and a regional air quality monitor does not always accurately represent the air you are breathing. Flow 2 allows you to see exactly what you are breathing.

Where Can I Buy Flow 2?

You can purchase Flow 2 from their international website.

Read 9 Comments on 'Flow 2 Review – Air Pollution Monitor'

  1. Thanks for the review of the Flow 2.

    But I would not be so positive about the Flow without cross checking with other portable devices like the AtmoTube PRO, which I find more reliable. I explain why.

    I have bought three Flows in the last 12 months: two of the first generation, and one Flow Gen 2. I lost the Flow Gen 2 while riding the bicycle just one month after I bought it, because the silicon strap is not as safe as the leather/plastic strap of Flow 1st gen.

    The two Flows 1st Gen have serious issues: one is reading the NO2 all over the place, very very high, and the second does the same with the PM2.5 and PM10. And there is no way to reset them. So they are not reliable in the real world.

    My AtmoTube Pro instead, which I carry with me on my bag every day since more than 1 year now, is still reading the PM2.5, PM1 and PM10 very accurately (I know this because I can I compare with other air monitors that I have at home like the Uhoo, PurpleAir, iQAir and others). It is therefore more reliable than the Flows, but it does not have a NO2 sensor and doesn’t have the very helpful map feature.

    Also, I have been writing to the Flow team about the issues with my Flows, but they don’t care to reply, so I am not trusting this company anymore. Not to mention that the Flow 2 costs now 199 Euro when it used to cost 159 Euro until just a month ago. That’s too expensive now. Too bad because I really would like to have a Flow monitor that can work properly, because with its features I find that it would be a perfect air monitor if it worked properly.

    1. Hello Andrea, thank you for taking the time to give your thoughts on the matter. It’s always good to hear other opinions and experiences.

      I will definitely look into reviewing other similar devices when I get the chance – I have reached out to Atmotube but have yet to get a reply. Once I can test one myself, I will definitely compare the products.

      I am sorry to hear about the issues that you have had. My Flow 2 is still relatively new, and I will be using it a lot over the coming months. I will make sure to keep this post updated in regards to the wear on the straps.

      From my personal experience, though, testing them compared to official monitors, Flow 2 did appear to be accurate within a small percentage. I have also tested it against other monitors that I have access to (uHoo and laser Egg) and have always found it to be quite similar in reading.

      Of course, these are just my experiences and I can only write from what I have experienced. However, I will make sure to keep this article updated with my future thoughts on the product and if anything changes it will be reflected in this article.

      I am trying to find a way to get access to a lab quality monitor for future comparison, but so far that is proving very hard. I am doing my best though, as I want to improve the quality of my reviews in the future.

      Again, thank you for taking the time to offer your personal experiences. I will work on keeping this review updated and accurate and as soon as I have other (hopefully lab tested) devices to compare to, I will.

  2. Dear Ethan, thank you for the excellent reviews of the Flow 2, the Atmotube Pro and others. One thing I liked about your Atmotube Pro was that you described the brand of sensors used inside the product, and linked to a page Atmotube had on their site showing the exact brand model numbers of the internal sensors (for example, it uses the Sensirion SPS30 for PM1, PM2.5, PM10 measurements.) This info is SUPER HELPFUL when evaluating a device, because a) we can see which devices use which sensors and b) we can also read independently about what those makes / models of sensor are good at or bad at. (For example, the Sensirion has a unique design which keeps dust particles from building up and causing unnaturally high readings.)

    Would you update your Flow 2 review in these comments with information about what brand / model of sensors it uses inside? Thank you!

  3. Thanks for posting this review. I’ve had a Flow 2 for about 6 weeks now and I agree that the app could do better at showing/graphing the data over time. I have my data exported from Plume now and can see it in the spreadsheet. Do you have any recommendations for how to convert this info into graphs?

  4. I’m sorry to report that I’ve had a similar experience to Andrea with the Flow. The lack of response to questions and inquiries from their dedicated help-desk sounded especially familiar, and made me start wondering how reliable their other data might be. Here in Okinawa, the Japan Meteorological Agency and IQ Air consistently report lower levels of pollution than Plume labs or the Flow device. Compared with other Japanese prefectures, Okinawa almost certainly has the highest pollution levels, but very low levels of public awareness. For this reason, I would very much like to be able to share accurate information.

Leave a Reply

If you want a quick reply, ask on the forum instead!