Nature and Biodiversity

5 ways new monitoring technologies can help cities combat air pollution

The City of London on a smoggy morning.

The City of London on a smoggy morning. Image: Reuters/Kieran Doherty

Elizabeth Fonseca
Senior Manager, Air Quality, Environmental Defense Fund Europe
Matt Whitney
Head of Data, Clean Air Fund
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• Air pollution is damaging our health, but there is often a lack of local data made available to identify solutions.

• A world-leading pilot project in London deployed and tested new monitoring technologies that can help to fill these data gaps.

• A detailed blueprint has launched to help cities take forward the lessons learned to better understand and reduce air pollution.

Around the world, nine out of 10 people breathe unhealthy air. This statistic is alarming, particularly given new information about how air pollution is damaging people’s health and shortening lives. The health impacts of poor air quality go far beyond heart and lung disease, with new research identifying how it is linked to a wide range of other health impacts including eyesight issues, infertility and long-term cognitive impacts

Yet there is a lack of data that is inhibiting targeted, meaningful action to lower pollution. OpenAQ – a non-profit dedicated to sharing open air-quality data – found that only half of the world’s governments produce or share such data.

Local pollution data can provide policy-makers with actionable information, but the financial resources and expertise needed to deliver this information aren’t accessible to many cities. That’s why we undertook the Breathe London pilot project: to demonstrate how lower-cost monitors and mobile monitoring can generate useful data and insights about air pollution, and to package everything we’ve learned into an accessible blueprint to help cities achieve their clean air goals.

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London was an ideal place to test emerging monitoring technologies. The city already has an extensive regulatory network, comprised of reference-grade air-quality monitors, as well as support from the Mayor of London and existing policies aimed at reducing air pollution. One of these policies is the world-leading Ultra Low Emission Zone (ULEZ), which charges the most polluting vehicles to enter the city centre.

The Breathe London pilot sought to use London as a testbed to advance the science around lower-cost air quality monitoring and help make invisible pollution visible. With 100 lower-cost sensor “pods” and two specially equipped Google Street View cars, the Breathe London pilot project complemented London’s existing regulatory network and was used to help measure the impact of the ULEZ.

The use of low-cost monitoring equipment allowed Breathe London to compile more localized pollution data
The use of low-cost monitoring equipment allowed Breathe London to compile more localized pollution data Image: Breathe London

Over the course of two years, the Breathe London pilot team compiled critical lessons learned and important scientific insights into how to establish, maintain and use data from a lower-cost monitoring network. We produced a guide with these key lessons and behind-the-scenes knowledge that can help other cities interested in using new monitoring approaches to tackle air pollution.

Here are five ways emerging technology can help cities advance clean air action:

1. Target the timing of action

Emerging monitoring technology can enable leaders to better understand when people are most exposed to air pollution to inform targeted actions that can reduce exposure. Lower-cost monitors are cheaper and more portable than traditional air quality monitors, and so can be fixed at many locations across a city to provide continuous data that shows how pollution rises and falls over time, which can be particularly useful in places where vulnerable people live, work and visit.

NO2 levels outside a London school by hour
NO2 levels outside a London school by hour Image: Breathe London

For example, one-third of the Breathe London pilot project’s monitors were sited at schools. Data from these monitors revealed pollution is typically highest during a weekday morning. An example 24-hour graph at one of the Breathe London schools (see above) shows how levels fell approximately 30% during the middle of the day from a morning peak, before climbing to an evening peak. Armed with this type of information, decision-makers can reduce students’ exposure by planning recess and outdoor activities at times with the least pollution.

2. Find pollution hotspots

If cities want to reduce air pollution but don’t know the best location in the city to start, they can use lower-cost monitors and mobile monitoring to identify pollution hotspots. During the Breathe London pilot, one of the monitors was consistently measuring higher NO2 pollution levels than the rest of the network (see below), as much as more than 100% higher during morning and evening peaks. The monitor was near the entrance of a bus garage, at the end of a residential street.

NO2 levels outside a London bus garage
NO2 levels outside a London bus garage Image: Breathe London

After we shared the data with the responsible government entity, they immediately began working with the bus operator to find ways to reduce pollution at this hotspot, including stopping buses idling outside the garage, alongside the planned upgrade of some of the bus fleet. Data shows that pollution levels have since gone down, reducing the exposure of those living around the bus garage to harmful air pollution. Once again, continuous monitoring allowed us to see which times of the day the pollution levels were at their worst, so actions could be targeted accordingly.

3. Measure the impact of an intervention

Cities can use lower-cost sensors and mobile monitoring to estimate air quality improvements brought about by interventions, or actions to reduce air pollution. With Breathe London data, we examined the impact of the ULEZ on air pollution and found a 25% drop in nitrogen dioxide (NO2) levels at monitoring sites inside the zone near roads.

After the COVID-19 pandemic hit, we also assessed the impact of London’s “lockdown” measures on air pollution in March 2020 and found the greatest pollution reductions were between 6.00 and 22.00, with NO2 falling by nearly one-third during these hours inside the ULEZ boundary (see below).

The impact on London pollution of the first COVID-19 lockdown
The impact on London pollution of the first COVID-19 lockdown Image: Breathe London

4. Raise awareness

Emerging monitoring technology provides local air quality data that can raise awareness and help people better understand pollution where they live. Through the Breathe London pilot, we provided the public with both current and historic pollution levels – as well as street-by-street pollution data from our mobile monitoring – together on one user-friendly, interactive platform that centred a real-time map (see map at top). The map showed people when pollution was elevated, as well as how pollution had changed at each monitor over the past 24 hours. This type of platform is just one way to use hyperlocal data to raise awareness. Marketing and communications experts can help cities identify the target audiences and determine which messages will speak to those audiences.

5. Provide a powerful tool for producing air quality data

Breathe London’s lower-cost monitors produced robust data, allowing us to make insights comparable to reference-grade monitors across the network and helping provide a more detailed understanding of London’s pollution. For all of the national governments that want to collect or share open air-quality data, lower-cost sensors and mobile monitoring are valid options for generating useful, reliable data.


What is the World Economic Forum doing to ensure smart cities?

Emerging technology has an essential role to play in tackling the air pollution crisis and protecting people’s health. The Breathe London pilot project demonstrated that lower-cost sensing technology can help cities target their resources to paint a clearer picture of air quality. With hyperlocal data showing when and where pollution is elevated, cities can implement targeted interventions and ensure funds go to the communities most burdened by the health impacts of air pollution.

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Nature and BiodiversityUrban TransformationFourth Industrial Revolution
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