Measuring airquality with your Android phone!

Kategorie: Allgemein

Why measure and do this?

This is an english summary of my page about my little air quality sensor.

The story behind it is explained very simply: One day I decided to visit the people of in Stuttgart and have a look at their project. They have cleverly designes a particular matter sensor for both PM10 and PM2.5 that costs less then 30 Euros.

Because of their small size, particles on the order of 10 micrometers or less (PM10) can penetrate the deepest part of the lungs such as the bronchioles or alveoli. Similarly, so called fine PM, (often referred to as PM2.5), tend to penetrate into the gas exchange regions of the lung (alveolus), and very small particles (< 100 nanometers) may pass through the lungs to affect other organs. So these particles are not something you should take lightly. And these particulates are a good indicator for other Air polutants such as NOx. Both are caused by burning stuff, either to heat your house or when you drive around in a car.

The effects of inhaling particulate matter that have been widely studied in humans and animals include asthma, lung cancer, cardiovascular disease, respiratory diseases, premature delivery, birth defects, and premature death.


In Europe PM10 particulates should not exceed 50 µg/m3 on a Daily average for more then 35 days. The worst air in Germany is often found in Stuttgart, but Freiburg beeing in a valley also has problems. Thats why I decided to put upt he first sensor from this citizen science network.

The graphics you see are taken from my sensor outside on my balcony. The grey thing next to my little polar pear houses the sensor. You can build these fairly easy yourself.

These graphics should be refreshed every 15 min. This one shows the measurement over one week. Note 50 µg/m3  are the limit:

To see if the 50 µg/m3 for PM10 has been broken, see this chart:

Besides that the sensor also gives you the value for PM2.5, here the chart for the last 24 hours. The EU hast no limits for particles in that size.

But the sensor also measures temperature:

and humidity:

For more information consult the wiki article.

how it came to this?

One day in January I decided to go to Stuttgart to met with the people from I had heard about their project:

They are building Do-It-Yourself air quality monitors. You can hang on your balcony and the device pushes the data to a central map for everyone to see (

So citizen can measure the air quality in their neighbourhood. In total there are less then 20 measuring points run by the state of Baden-Württemberg all across it’s territory.

So I built this one sensor and took it to Freiburg. And I decided to organise a workshop and send out invitations. I ordered the stuff for ten sensors and thought if I have some to spare I can talk my friends into putting some up.

The first workshop was overrun by more then 30 people, the second workshop was again overrun by more then 30 people. Workshop three and four are already planned. So Freiburg has now more then 20 sensors and more are coming. The side effect is, that people who are usually not interested in these topics start talking about air quality and get involved.

While doing this I met so many people interested in smart city, sensors and environmental quality. So we decided to maker our little project and build a portable air logger, more or less a dosimeter but for particle matter and not for radioactivity. You will be able to take it along when you go through town and measure to which particle matter concentration you are exposed. As soon as this device is ready I will test it while cycling, running or going around town in the ambulance. Maybe I can even lend it out to policemen on the beat, street sweepers, trash collection workers or bike couriers, because currently there is no real data or research about the personal exposure to bad air and how it varies based on lifestyle or occupation.

Several professors at the university already expressed their interest. You can find the project here.

However the website is not yet finished. We are planning to put instructions on this website so that everyone can build such a device himself.

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