European Citizens Measure Air Pollution With Their Smartphones

Press Release From: Leiden University
Posted: Monday, September 7, 2015

The successful Dutch iSPEX-project [1] that enlisted the general public to contribute to the understanding of air pollution is being scaled up and running its first Europe-wide citizen campaign: iSPEX-EU. From 1 September to 15 October 2015, thousands of citizens in major European cities take to their streets, squares and parks to measure air pollution with their smartphone. Participating cities include: Athens, Barcelona, Belgrade, Berlin, Copenhagen, London, Manchester, Milan, and Rome.

iSPEX-EU distributes small devices that can be attached to smartphones [2] to turn them into optical sensors. These add-ons are “spectropolarimeters” that, in combination with the phone’s camera, sensors, computing and communications capabilities can be used to measure tiny particles in our atmosphere. These particles can be of natural origin, such as sea salt or tiny ash particles from forest fires or volcanic eruptions, through human-made soot particles produced by traffic and industry, and contribute to air pollution and its impacts on our environment and health in an as-yet poorly understood way. For example, they form one of the largest uncertainties in our current estimates of climate change.

The application of iSPEX is two-fold: 1) It enables crowd-sourced measurements of tiny atmospheric particles, also known as aerosols, at locations and times that are not covered by current air pollution monitoring efforts. 2) It makes atmospheric science accessible to everyone, by active participation in scientific measurements.

The iSPEX app instructs participants to scan the cloud-free sky while the phone’s built-in camera takes pictures through the add-on. Each picture taken through the iSPEX add-on contains information on both the spectrum and the linear polarization of the sunlight. The measurements taken using the phone camera can provide unique information about the properties of the particles in the air, including the amount of particles, their size distribution and the type of particles. This type of measurement is crucial in assessing the impacts of atmospheric aerosols on environment and health.

With the advent of smartphones and the development of iSPEX, citizens can now contribute to these crucial measurements and together form a flexible network that can deliver measurements from cities across Europe, even where no specialised equipment is available, and at any daylight hour —under cloud-free conditions. The active involvement of citizens in an important and real scientific experiment, pioneering a new form of citizen science where participants carry out complex, simultaneous mass-measurements, is the most important aspect of this project.

The citizen science approach was successfully trialled at national level in the Netherlands in 2013. Organised by the Dutch iSPEX-project, the initiative involved three national measurement days with thousands of citizen scientists throughout the country performing measurements of their cloud-free sky. This led to the assembling of atmospheric particle maps of the Netherlands that achieved higher detail than those available from satellite monitoring and filled blind spots of established ground-based atmospheric measurement networks [3]. This success resulted in iSPEX-EU, the European expansion of this citizen science approach in contribution to an improved understanding of air pollution and its various impacts.

For the setup of this campaign the iSPEX-EU team, led by Leiden Observatory [4], works closely with local partners [5] in all cities, including research organisations and environmental protection agencies. These partners are taking up the co-ordination of the citizen science campaign in their city. They play a crucial role in recruiting and motivating citizens to actively participate by performing numerous iSPEX measurements throughout the campaign period, which is the key to a successful iSPEX-EU campaign.

iSPEX-EU is organised as part of the EU-funded project LIGHT2015 [6] and is one of the many activities running during the International Year of Light and Light-based Technologies 2015 [7], a worldwide celebration of light and light-based technologies this year.

For more information visit and Follow also the twitter @ispex_eu and @LIGHT2015Europe accounts for the latest updates.

Image and animation:
Hi-res images and animated introduction film:


[1] The iSPEX project is a collaboration between Leiden University (LU), the Dutch Research School for Astronomy (NOVA), SRON Netherlands Institute for Space research, KNMI Royal Netherlands Meteorological Institute, and RIVM National Institute for Public Health and the Environment, all in The Netherlands. The iSPEX add-ons were produced by Bright Led Solutions and the app was programmed by DDQ, both in the Netherlands. For the initial Dutch campaign of the iSPEX project in 2013, Longfonds, CNG Net, KIJK and Avantes helped recruiting participants. The iSPEX project was first made possible with the support the €100’000 award from the Academische Jaarprijs 2012.

[2] The iSPEX add-on currently fits on the iPhones 4, 4S, 5 and 5S.

[3] The scientific results of the initial campaign of the Dutch iSPEX project in 2013 are published in this article:
Mapping atmospheric aerosols with a citizen science network of smartphone spectropolarimeters
Frans Snik, Jeroen Rietjens, Arnoud Apituley, Hester Volten, Bas Mijling, Antonio Di Noia, Stephanie Heikamp, Ritse C. Heinsbroek, Otto Hasekamp, Martijn Smit, Jan Vonk, Daphne Stam, Gerard van Harten, Jozua de Boer, Christoph Keller, & 3187 iSPEX citizen scientists. Geophysical Research Letters 41. doi: 10.1002/2014GL061462

[4] Leiden Observatory is part of Leiden University, one of Europe’s foremost research universities and lead institute of the iSPEX project. Its astronomical instrumentation researchers have developed the iSPEX smartphone add-on. Leiden Observatory is the world’s oldest university observatory and is one of the world’s leading astronomical institutes with over 25 faculty and over 70 PdD students. Leiden Observatory plays an active role in astronomical outreach activities at local, national and international levels. It hosts the Universe Awareness (UNAWE) programme, which educates and inspires young children. With iSPEX add-on and app for the smartphone, Leiden Observatory introduces a new measurement technique for tiny atmospheric particles that make significant part of air pollution, but more important, also a modern measurement philosophy: citizen science.

[5] The iSPEX-EU campaign is organised by the iSPEX and LIGHT2015 projects in close co-orporation with local partners in nine European cities. These partners include the National Observatory of Athens (NOA/IAASARS), ICFO- the Institute of Photonic Sciences, the Centre for Research in Environmental Epidemiology (CREAL), the Institute of Physics Belgrade (IPB), MINT Impuls, Freie Universität Berlin (FUB), the Danish Environmental Protection Agency, The Institute of Physics (IOP), the Science & Technology Facilities Council at the Rutherford Appleton Laboratory (STFC-RAL), the University of Manchester, the Italian Aerosol Society (IAS), Cittadini per l’Aria, the Institute of Atmospheric Sciences and Climate at the National Research Council of Italy (ISAC-CNR).

[6] LIGHT2015 is a European project funded through the European Union’s Horizon 2020 research and innovation programme of the European Commission. It aims to promote the importance of photonics to young people, entrepreneurs and the general public in all Member States of the EU during the International Year of Light and Light-based Technologies 2015 (IYL 2015). LIGHT2015 activities will include LIGHTtalks, a series of inspirational events, which will take place throughout the European Union in different cities at different times for the whole duration of the project in order to bring photonics closer to students and entrepreneurs. A specific series of events targeted to local industry and entrepreneurs, will take place during the period 25-28 September 2015 to take advantage of the international “100 Hours / Weekend of Light” of the global IYL 2015 programme. Another highlight of LIGHT2015 will be a community experiment on smartphone photonics where thousands of participants from throughout the EU will carry out optical measurements of the sky to yield information related to air pollution. To aid teachers and to inspire students, photonics kits will be distributed to schools around Europe to support the scientific education at secondary schools. LIGHT2015 partners include the European Physical Society (EPS), the European Optical Society (EOS), ICFO- the Institute of Photonic Sciences, Politecnico di Milano (POLIMI), the National University of Ireland Galway (NUI), Leiden University (LU), and EYESTvzw.

[7] The International Year of Light and Light-Based Technologies (IYL 2015) is a global initiative adopted by the United Nations (A/RES/68/221) to raise awareness of how optical technologies promote sustainable development and provide solutions to worldwide challenges in energy, education, agriculture, communications and health. With UNESCO as lead agency, IYL 2015 programs will promote improved public and political understanding of the central role of light in the modern world while also celebrating noteworthy anniversaries in 2015—from the first studies of optics 1,000 years ago to discoveries in optical communications that power the Internet today. The IYL Global Secretariat is located at the Abdus Salam International Centre of Theoretical Physics (ICTP). The Founding Partners of IYL 2015 are the American Institute of Physics (AIP), the American Physical Society (APS), the Deutsche Physikalische Gesellschaft (DPG), the European Physical Society (EPS), the Abdus Salam International Centre of Theoretical Physics (ICTP), the IEEE Photonics Society (IPS), the Institute of Physics (IOP), Light: Science and Applications, the International Network, 1001 Inventions, The Optical Society (OSA) and the International Society for Optics and Photonics (SPIE). Patron Sponsors include Bosca, the International Association of Lighting Designers (IALD), Royal Philips Lighting, Thorlabs and UL.

// end //

More news releases and status reports or top stories.

Please follow SpaceRef on Twitter and Like us on Facebook.