I love portable devices and miniaturisation is a thing of the future. In this post, I am going to compare Flow 2 and Atmotube Pro side by side. Both devices are two portable Air Quality Monitors that can easily be carried around and help you see the air you breathe.

This is a preliminary test and I will compare the devices between each other. I have promised you an extensive comparison between the portable monitors and an official reference station, however, it will take a bit longer in order to sort things out with the local AQ department − paperwork which needs time from their end.

Tech SPECS Comparison

Atmotube Pro

• Weight: 93 grams / 0.2lbs
• Dimensions: 84х45×22 mm / 3.3×1.7×0.8 inches
• PM 1.0
• PM 2.5
• PM 10
• MEMS TVOC sensor with automatic calibration
• Barometer
• Temperature
• Humidity
• Bluetooth 5.0
• Up to 10 days on a single charge

Flow 2

• Weight: 70 grams / 0.1lbs
• Dimensions: 125x40x35 mm / 4.9×1.5×1.3 inches
• PM 1.0
• PM 2.5
• PM 10
• NO2 sensor
• VOC sensor
• Bluetooth 5.0
• Up to 3 days on a single charge

Comparison

If something is important for a portable AQ monitor is the weight especially if you carry it on you and you don’t attach it to your bike. The winner here is Flow 2 which is 23gr lighter than the Atmotube Pro.

Flow 2 has an extra gas sensors for Nitrogen Dioxide (NO2) monitoring, which Atmotube Pro doesn’t have, but on the other hand, Atmotube Pro has a temperature, humidity and atmospheric pressure sensor that makes it more suitable for those who want to measure the environmental parameters, I will call it a tie here.

Some users complain about the battery performance of the Flow 2, it lasts for about 3 days but the problem is that it turns off the sensors to save energy when it sensing that you don’t move it around a lot. If you really think about it, it makes some sense the way it functions as it is a portable device and it was designed to take measurements on the go, for this reason, I think the company includes the base. The base gives a solution to this problem. Atmotube Pro can last up to 10 days and the user can choose how often he wants to take measurements. I think Atmotube Pro is the winner here as it offers some options to the users.

The sensors

The VOC data between the two monitors are not easy to compare, they are two different sensors and basically, it is very hard to determine what each of them measures. Some users have complained about weird measurements from both devices, and I have tried to explain to them (see explanation below) that this is normal and for the current technology of the low-cost gas sensors.

Gas sensors like the NO2 and VOC are very susceptible to interference by other gases, as a result, low-cost gas sensors are very bad at measuring accurately the concentration of the desired pollutants. Another common problem they face is that pollution gas molecules stuck on the surface of the sensors and keep exciting the sensor for a longer time. Finally, some sensors, especially the VOCs, are black-boxes which means the manufacturers don’t disclose technical information to the developers in order for them to create the appropriate software or to improve the firmware. Over time, I have suggested that companies have to change the way the devices display the pollution concentration for VOC and other gases when they use low-cost sensors. Instead of an exact value, like 120ppb, which most likely will be inaccurate, they have to create an index value with ranges for different concentrations. That way the margin of error is low and users don’t get confused.

Here, I want to mention that some companies, like the Fraunhofer- EMFT, have developed some MEMS micropumps which are able to forces gas molecules away from sensor surface, as a result, it eliminated sensor drift. It will be a nice idea to see future devices with these micropumps.

There is a small issue with the graph above and below as Atmotube uses ppm and PlumeLabs uses ppb. 1ppm=1000ppb which makes the graph really hard to compare. However, I kept both measurements on the same scale, out of curiosity to see if there is any correlation. There is a correlation but I don’t understand how can measure more or less the same concentrations but on such a different scale. I think there is a mistake with the log file (.csv) were measurements are saved, maybe the developer mistyped ppb or ppm.

The particulate matter sensors tell a different story as they seemed to follow the same trajectory but with the difference that Flow has more fluctuations during the measurements. Both sensors seem that they can’t reach zero concentrations and the lowest concentration for PM2.5 is 2μg/m³. Something else that I noticed is that when the PM1 output is 1μg/m³ the PM2.5 output is 2μg/m³ and the PM10 output of the sensor is 3μg/m³ for both devices.

 

The Apps

Most users and I agree that Flow’s user experience (UX) is better than Atmotube’s UX, don’t get me wrong Atmotube’s app is nice too but has a different logic behind it. Flow bases the measurements histogram to the location of the device, as a result, it creates nice maps and you can easily pinpoint the location which you have to avoid in the future. On the other hand, Atmotube has real-time visualisation of the pollutants, temperature, humidity, and pressure and makes it more useful at the time you are exposed to air pollution plus there are a ton of options in Settings. I will call it a tie as it depends on what is important to you.

Conclusion

All in all, I see both devices equally good, the build quality is nice and I think both devices serve a different approach to air pollution. Which one do you think is better for your needs?

Stay tuned for the next article with an official in-depth comparison.