Citizen science to monitor pollution with iPhones

Aerosols and pollutants have an increasingly damaging impact on health, the environment and the economy. The Institute of Physics, UK, helped to run a citizen science measuring particles in the atmosphere.

The curious English phrase ‘pea-souper’ emerged in the 19th Century to describe the thick, greeny-yellow fog that appeared as the UK industrialized.  The word ‘smog’ was coined in the 20th Century, a kind of smoky fog in cities partly due to the use of domestic coal, but also famously in the case of Los Angeles due to emissions from cars that reacted with other pollutants. Photographs of the London ‘pea-souper’ of 1952 that is estimated to have killed 4,000 people show streets and citizens wrapped in thick fog, while the images of the Los Angeles smog made the case for environmental activists.  In 2015 in the West, pollution is often less obvious but its impact is significant. 

This is why the iSPEX citizen science project, which originated in the Netherlands at the University of Leiden in 2013, became a Europe-wide initiative in autumn 2015. Using technology developed for the iPhone, people in Athens, Barcelona, Belgrade, Berlin, London, Copenhagen, Manchester, Milan and Rome were invited to take measurements of air pollution. The UK partners are the University of Manchester and the Institute of Physics, and funding for the iSPEX project currently comes from a European Union Horizon 2020 grant as part of the International Year of Light 2015. Manisha Lalloo, Public Engagement Manager at the Institute of Physics explains, “We got involved through the International year of Light, they were looking for a citizen science project to get involved in.” 

Damage to crops, buildings and health

Part of the Institute of Physics’ commitment is to encourage learning about physics in culture, and involves ‘reaching out to people who are not necessarily schoolchildren [and] also those who are less well served by outreach projects, independent adults, it’s a nice project for us to get involved in from that perspective,’ says Lalloo. While air pollution might not be as immediately and extravagantly visible as in the past, the impact on health and the economy are increasingly visible. The European Commission has estimated that ‘direct costs to society from air pollution, including damage to crops and buildings, amount to about €23 billion per year, and the external costs from health impacts alone are estimated at €330-940 billion (3-9% of EU GDP).’   

The iSPEX project uses citizens to get a map of how clear the atmosphere is, measuring aerosols, or atmospheric particles in the atmosphere. 90 percent of these aerosols are from nature, such as soot, sea salt, volcanic ash, or sand from sandstorms. The remaining 10 percent are manmade, produced by industry, cars or the burning of fossil fuels and biomass.  Generally light-coloured aerosols act to cool the climate reflecting sunlight, while dark-coloured aerosols absorb it. The aerosols interact with clouds, and this, according to the International Panel on Climate Change is, ‘the largest source of uncertainty in climate sensitivity estimates.’ Aside from the health and economic impact of air pollution, the impact of aerosols on climate change is uncertain. 

Instant readout

The iSPEX project involves citizens downloading an app for their iPhone, and a small plastic device, called a spectropolarimeter which is ‘like little penguins that you slot onto your phone,’ explains Manisha Lalloo. ‘It has a lens and when you download the app it uses the camera though the device.’

Citizens were asked to go outside on a clear cloudless day, and point the app to the sky. ‘They had to hold their iPhone out directly above them,’ says Lalloo, ‘it looked at the atmospheric particles in the air via the polarization of the light being picked up by the camera on your iPhone.’ The data, including time and location, was then shared with a central database with measurements from other European cities. ‘The way that this is measuring pollutants and aerosols in the air is different to the more high-tech devices stationed in fixed places run by scientists and looked at by researchers,’ says Lalloo. ‘This is to supplement that, to give a bit of a wider view of what pollution is looking like in cities.’ 

While the data itself is really useful at getting people involved, the project amplifies the message and makes the issue more visible. ‘It gets people more involved and gives them a picture of their local area too. When you do the measurement you get an instant readout on the phone,’ explains Lalloo. We mightn’t use words such as ‘pea-souper’ or ‘smog’ to visualize pollution in our 21st Century atmosphere. But increasingly Citizen Science is giving us a different way to explain and connect. Projects such as iSPEX aren’t just about generating wider data, they are about socializing science, making science a tool of daily life, enriching our understanding of our world and giving us a sense of how we can make the world a better place.