In-Depth: Atmotube Pro

It will please some of you to know that I am going to compare Atmotube Pro with other Particulate Matter sensors and monitors. First with an outdoor monitor and in this case the Luftdaten DIY and second the AirVisual which is more of an indoor monitor.

Before I begin with the comparisons I want to dive a bit deeper and tell you that apart from exporting the .csv from the app directly, you can also access Atmotube’s .csv files (in case you have an iPhone) from the File Sharing service iTunes provides when you connect your phone with your computer (macOS & Win). This way you have more control over which days you upload to your computer.

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Call for Volunteers

Thanks to uRADMonitors generosity and determination to beat air pollution I am going to give away 10 uRADMonitor SMOGGIE.

I am searching for Volunteers all around the world who are willing to install an Air Quality Monitor in their backyard or balcony or window or any other outdoor environment in order to build a better air quality network and to help you raise awareness in your neighborhood/ community.

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Review: Atmotube Pro

Wearable or portable devices are not so often considered important in order to protect yourself from air pollution. Most ads claim that we spend 90% indoors and we need an indoor AQ Monitor which is true but we also move around we go to work or we visit friends and family who don’t have an AQM in their house or simple they are not aware of the problem.

Here comes the new Atmotube PRO a small portable AQM equipped with a laser scattering PM1, PM2.5 and PM10 sensor. It also features a VOC sensor and a complete weather station with humidity, temperature and barometric sensor.Read More »

uHoo a Portable AQM?

The idea of having an Air Quality Monitor anywhere you go seems good especially when you can have 9 sensors with you. So here is a tip on how to convert a stationary IoT indoor AQ monitor to a portable one, in this case I will demonstrate it with the uHoo because I really want to measure some NO2 and O3 concentrations in some busy spots of the city.

There two ways to do that, one of which isn’t easy but bear with me.

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Cheap Face Mask, Worth it?

Over the years, I have reviewed some very good face masks on See The Air like the Cambridge Mask and Vogmask. The only backward is the price especially when you have to buy them frequently because you wash them often and you wear them a lot. There is a solution by using masks such as the AirGo which allows you to chance the filters and the neck warmer is durable and washable and the O2 Canada Respirator which allows you to change filter easily. However, I wanted to try a cheap and lightweight face mask for the summer which will cost around $3 and it will have the ability to use exchangeable filters because I want to be able to wash it once a week.

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PurpleAir-II vs Luftdaten

A USA air quality monitor in comparison with a DIY German air quality monitor. How well do they perform with each other? Full disclosure, the software the monitors run is developed in the mentioned countries. The components from both devices are made mostly in China.

  • We already know PA-II’s correlation of coenficency R²≈0.87 with the corresponding FEM GRIMM and FEM BAM.
  • The SDS011 sensor which is most commonly used in the Luftdaten project has a correlation of coenficency  ≈0.84.

The PA-II features a double PMS5003 laser sensor. The PA-II module averages out the values from the two sensors, so in case one of the two sensors registers unexpected high readings, (perhaps some dust or insects etc) this technique makes the readings less questionable. The Luftdaten DIY project as we have mention above mostly uses one SDS011 laser sensor. However, the Luftdaten software supports many PM2.5 sensors including the PMS5003 series among others.

Analysis

My friend Ashley from Plume Plotter has already done a comparison between the Purple Air PA-II, the Luftdaten SDS011 and DEFRA for a complete year of data link.

First of all, by comparing PA-II’s two identical sensors we can see on the graph below that the Sensor B has the tendency to register higher concentrations over time, on my device, maybe another device has a different behavior. So the process of averaging out the concentrations from both sensors has some positive results.

Many scientific papers insist that the PMS5003 and SDS011 sensors are nephelometers and not particle counters. Which means that they are influenced by humidity. Nephelometer comes from the compound Greek word nephelo “Νέφος” which means cloud.

I live in an area with high humidity. Right now the official RH is 83%. The PA-II registers 51.6μg/m3 and Luftdaten 38.3μg/m3. The difference between them is huge. However, both devices are mistaken. Purely for your information the humidity sensor in the Luftdaten device measured RH 94% the PA-II measured RH 53% and AirVisual measured RH 72%. From my experience, I would say that the relative humidity is definitely above 80%.

From the graph below we can see the same results. The PM-II overestimates the PM2.5 concentrations most of the time in comparison with the Lufdaten sensor. Both devices seem to measure the same fluctuations over time so there is some correlation. The humidity that day started low at RH 30% and climbed up to 60% at the end of the day. There is an influence between humidity and how the sensors and especially the PA-II measure PM2.5 concentrations without any doubt.

PA-II Luftdaten 4-02-2019
SeeTheAir: 24h PA-II & Luftdaten side by side

Conclusion

The conclusion that I get from my everyday readings having the two devices side by side and from Plume Plotter’s analysis is that the PA-II overestimates the PM2.5 concentrations especially when relative humidity is above ~55% while the Luftdaten’s readings are more adjacent to the official readings.

Screenshot 2019-02-02 at 18.52.14.png
Plume Plotte: Regression lines for Luftdaten sensor and Purple Air PA-II sensor readings vs. actual (reference instrument) concentrations.