In the UK, around 40,000 deaths every year are attributable to exposure to outdoor air pollution, causing health problems that cost the country more than £20 billion annually, according to research from the Royal College of Physicians.

Nowhere is the problem more acute than in London. A King's College London study published in 2015 estimated that over 9,00 people in the capital die early each year due to long-term exposure to air pollution and there is little evidence that the situation is improving. Just a few weeks into 2018, air pollution in the capital had reached the legal limit for the whole year.

© iStock/Roddy1red
© iStock/Roddy1red

The impact has led London's mayor Sadiq Khan to declare that pollution in the British capital is "a public health emergency" and turned to a team of data scientists to help clean up the air.

In January, he unveiled Breathe London, a network of 100 monitoring stations and two Google Street View cars equipped with sensors that will together collect air quality data to create a real-time map of pollution. The mayor's office has called the initiative "the world's most advanced air quality monitoring network".

The network will be implemented by a consortium led by the Environmental Defense Fund (EDF) Europe, a US charity that previously delivered a smaller project of this type in Oakland, California. The results showed that air quality could get eight times worse from one side of a block to the other, a variability that conventional air quality monitoring systems were missing.

"Usually you have a network of stationary quality monitors that are usually operated by either the government or by researchers," Katie Moore, Manager of Air Quality Projects at the EDF, tells Techworld. "They're very expensive, and they can be spread out. The work in Oakland suggested that because there is such variability at a very small scale, there might be a lot that's been missed by those traditional air monitoring networks."

These variations could be the result of anything from traffic at an intersection popular with truck drivers to recycling plants that elevate chemical concentrations close to the facility. 

Her team then conducted a similar study in Houston, Texas, which added further evidence of the need for better monitoring systems. They then moved on to London for an expanded project.

"We have already started driving with the cars," says Moore. "And the London project is really exciting because it involves more than just mobile monitoring. We've also put up 100 stationary monitors, AQ mesh pollution monitors that'll be measuring mat static locations 24-seven.

"And we're also partnering with CERC [Cambridge Environmental Research Consultants], who will be doing some modelling. So we've three different pieces that we can use to understand more about air quality there."

Mapping a city

The Google Street View cars will take pollution readings approximately every 30 metres while they drive through London's streets. Sensor pods mounted on lampposts and buildings close to known air quality hotspots and sensitive locations such as schools and nurseries will also take readings.

Between them, they will collect millions of data points on nitrogen oxides, carbon dioxide, and small particles from areas of different socio-economic conditions and air quality concentrations to identify the connections between policy and pollution. 

The map that they create will help citizens understand the levels of pollution wherever they are but the ultimate objective is to assess the impact of public policy on pollution by analysing data from the areas it affects.

The cars began their journey in autumn 2018 and will continue collecting data for a year but the first results will be publicly released in the coming weeks.

"I think it's incredibly useful for city planners," says Moore. "It can be used in decision making about where to site things or where you might want to do more outreach for public health interventions.

"The hope is that we can provide some robust data that says these sorts of policy interventions work really well and contribute to reductions."