Live In The EU? Now Your Phone Is An Air-Quality Monitor

If you have a smartphone, you’re now a citizen scientist.

If you see somebody in Europe spinning around, snapping photos of the pale blue skies with their phone, don’t worry for their sanity. They’re (probably) just measuring pollution. iSPEX-EU is a large-scale project that lets citizens measure air quality all over the continent.


The six-week project runs until October 15 and is based on the success of a one-day trial in the Netherlands. To take part, participants need a little lens–called a spectropolarimeter–that clips over their phone’s camera. Then, using the provided app, they snap several photos of the sky, all in different directions.

The app measures three things. The light spectrum, the polarization of the light, and the exact position and direction the picture was taken in. This data is aggregated at iSPEX HQ, where it is used to make maps.

Fine dust in the atmosphere, called aerosols, scatters and polarizes sunlight as it passes through. Depending on the size and makeup of these particles, the remaining light “changes” color. It’s the same phenomenon that gives us spectacular sunsets in polluted cities. iSPEX uses this information to make detailed maps of particulates suspended over the participating cities, including Athens, Barcelona, Belgrade, Berlin, Copenhagen, London, Manchester, Milan, Rome, and Toulouse.

The project exploits the proliferation of pocket computers that we all carry today, and it helps augment existing data because the sensors (citizens with phones) are mobile, not locked down to fixed spots. All that’s needed is a clear sky and a spare moment.

iSPEX complements projects like the Smart Citizen, a network of fixed sensors which measure carbon dioxide, nitrogen dioxide, temperature and humidity, light, and sound. Smart Citizen gives hyper-local data–you can check the air-quality on a single street, for example–but also requires special equipment. Other projects, like the Air Quality Egg, have had to shut down after funding ran dry.

But however it is gathered, citizen-sourced data is a valuable counterpoint to government data. First, it can fill in the gaps in official data, going where government sensors can’t or won’t. And it can also act as a way to double check official data–not that the government is organized enough to hide things, but a second pair of eyes always helps keep thing honest.


The next logical step would be to make all this environmental data available in one place. Our weather apps already source shared data from around the world, and apps like BreezeoMeter make a decent stab at aggregating data from U.S. air quality sensors, so why not a global air-quality forecast? The data is there. Someone just needs to put it all together.

About the author

Previously found writing at, Cult of Mac and Straight No filter.