About the project

What is the Breathe London project?

Using a comprehensive network of air quality monitors, Breathe London maps pollution at the street level to paint a clearer picture of the city’s air quality.

With cutting-edge sensor technology and research, Breathe London’s three complementary projects will help us understand what’s happening at the ground-level where people live, work and play:

  1. Breathe London installed a network of 100 state-of-the-art sensor pods on lampposts and buildings throughout the city, continuously transmitting air quality measurements.
  2. Specially equipped Google Street View cars used mobile sensors to measure air pollution on a variety of London roadways, taking readings approximately every 30-60 metres in representative areas of the city.
  3. In a linked study funded by the Greater London Authority, King’s College London used wearable sensors that allowed schoolchildren and teachers to monitor air quality during their journey to and from school.

Who is involved in the project?

Managed by Environmental Defense Fund Europe, Breathe London is a multi-partner project funded by C40 Cities, the Children’s Investment Fund Foundation and Clean Air Fund.

Breathe London brings together some of the UK’s top health and scientific experts with leading technology companies and the seasoned, science-driven advocacy experience of Environmental Defense Fund.

Together, Breathe London partners have unparalleled expertise in air quality measurement, technology design, atmospheric modelling and civic engagement. They include the Mayor of London, Air Monitors Ltd., Cambridge Environmental Research Consultants, Google Earth Outreach, National Physical Laboratory, King’s College London and the University of Cambridge.

Why collect air pollution data?

Millions of Londoners face health threats every day because of air pollution. Although the city has one of the world’s best air quality monitoring systems, there is still a lot it can’t tell us.

By mounting sensors to vehicles, lampposts and existing buildings, Breathe London can help identify pollution ‘hotspots’ that the existing network of fixed monitors cannot currently capture.

Measuring harmful pollution at thousands of locations informs data-driven solutions to clean up our dirty air and foster healthier, stronger communities.

How long will the Breathe London project last?

The sensors are collecting data from late 2018 to mid-2020, with all findings and data made public on our project website as it becomes available. The Google Street View cars collected data through October 2019.

Who is funding the project?

Through a competitive grant application, the project initially received funding from C40 Cities and The Children’s Investment Fund Foundation. The extension of the project received funding from Clean Air Fund. In addition, multiple partners have contributed grants and in-kind resources to support the implementation of this project.

Are you monitoring air pollution in other cities in the United Kingdom?

At the moment, we are not monitoring air pollution in other cities in the UK. However, we are testing innovative air monitoring methods that can potentially be replicated in other cities.

Who should I contact about media requests?

For media requests, please email media@breathelondon.edf.org or call +44 203 310 5912.

Data collection, methodology and results

What pollutants are you measuring and why?

All pollutants we measure are harmful to human health and have known association with adverse health outcomes. Some of the pollutants are also important contributors to climate change.

See our Air Pollution webpage for more information about sources and health effects of these pollutants.

Stationary Monitoring: Carbon dioxide (CO2), nitric oxide (NO), nitrogen dioxide (NO2), particulate matter (PM) in various size cuts (PM2.5 and PM10 are reported) and, in some locations, ozone (O3).

Mobile Monitoring: Black carbon (BC), CO2, NO, NO2, O3, PM2.5 (and other PM size cuts) and ultrafine particles (UFP).

How does the Breathe London network compare to the existing air-pollution monitoring network?

Breathe London’s approach reveals the locations and potential sources of pollution at a more granular spatial resolution than the traditional government monitoring networks.

The European Air Quality Directive has defined Data Quality Objectives (DQOs) for various air-pollution monitoring methods. The DQOs mandate that regulation and enforcement use regulatory-grade monitors, which provide higher certainty than lower-cost sensors like Breathe London’s AQMesh pods. However, the directive also recognises that indicative measurements – such as those made with the AQMesh pods – are useful in identifying geographic and temporal trends.

Therefore, the sensor pods complement the existing monitors and add another, more localised layer of air pollution information. EDFE, our technical partners and the Greater London Authority believe filling in this spatial gap in London’s air monitoring network is a critical, near-term step to tackling the city’s air pollution problem.

How can I access the data?

Near real-time data from the stationary monitors will appear on the Breathe London map as it becomes available. You can download the stationary monitoring dataset for NO2 here and PM 2.5 here. You can download mobile monitoring data from the Google Street View cars here.

You can also view and download the data on Environmental Defense Fund’s Air Quality Data Commons, which seeks to accelerate solutions to air pollution by standardizing and sharing air quality data.

Breathe London’s air pollution data API is now available for public use. If you are interested in developing your own third-party app and/or service please contact the project team on hello@breathelondon.edf.org with details of your request. Further information and instructions can be found via the API documentation.

Where does the data for the pollution sources on the map come from?

The Breathe London map shows the contribution of different sources of NOx pollution at monitoring sites across the city. The data on the map is based on the ADMS model setup for a ‘standard’ emissions scenario, using 2013 London Atmospheric Emissions Inventory (LAEI)* data for 2018 modelling hourly concentrations in µg/m3 from 1st April 2019 to 12th December 2019; this is described in more detail on the Methodology page under the topic ‘Identifying local pollution sources’.

The following table shows the 5 pollution source categories that can be explored on the map and a brief description of each source that was modelled.

Pollution Source Category Sources Description
Road Transport
Taxis, Other Cars and Motorcycles Includes petrol and hybrid cars, taxis, and motorcycles.
Diesel Cars Diesel cars used to transport people.
Vans Diesel and petrol light goods vehicles (LGVs).
Lorries Large, heavy goods vehicles (HGVs).
Buses and Coaches Transport for London (TfL) buses, non-TfL buses and coaches.
Industrial & Construction
Industrial Processes Sources of pollution related to industries including waste management and energy production.
Non-Road Mobile Machinery Industrial Includes mobile machines and transportable industrial equipment fitted with an internal combustion engine.
Non-Road Mobile Machinery Construction Includes mobile construction machines fitted with an internal combustion engine like diesel generators and excavators
Other Transport
Aviation Pollution from aircraft.
Rail Pollution from diesel fueled trains, including regional and national.
River Pollution from ships.
Domestic heat and power Pollution from the combustion of gas and other fuels to produce heat and power for homes.
Commercial heat and power Pollution from the combustion of gas and other fuels to produce heat and power for commercial buildings.
Outside London Air pollution that is not produced in London but is transported into the city by the wind from further away. This component is also known as ‘background’.
Residual Residual pollution includes other sources such as home and garden activities and sewage treatment.

*The 2013 LAEI was published in 2016.

Air pollution and health

What have you learned about London air quality so far?

Air quality can vary substantially depending on where you are in the city. The project team is currently assessing the preliminary data and will share insights on a regular basis. Initial analysis from the first 9 months of operation indicated that nearly half of the sites measured by Breathe London are at risk of illegal air pollution levels for nitrogen dioxide..

Please sign up for updates or follow us on Twitter at @Breathe_London.

Do the observed air pollution levels meet regulatory guidelines?

At each sensor site, we provide the current average pollution levels, as well as pollution levels measured since the beginning of the project. We also provide the World Health Organisation’s (WHO) short-term guidelines (recommended limits for daily or hourly exposure to a given pollutant) and long-term guidelines (limits for annual exposure). Most of the stationary data presented here are averaged over an hour.

Breathe London refers to the WHO guidelines as they are the most protective available. Although the WHO guidelines are not legally binding, they have been developed by public health experts based on substantial research to help the UK and other governments set pollution limits for protecting human health. See more at WHO Air Quality Guidelines.

The Breathe London project is studying the accuracy of these lower-cost sensors to better understand how they compare to more costly and bulky ‘reference monitors.’ Until the study is complete, the data is provisional and comparison to any health criteria guidelines should be considered indicative only.

What does this data tell me about how air pollution affects my health?

Millions of Londoners face health threats every day because of air pollution. WHO recommends maintaining concentrations of air pollution that are as low as possible, especially to protect sensitive groups such as children, older people or people with pre-existing health conditions. Recent evidence indicates that exposure below the standards may also affect health.

Breathe London’s granular, local monitoring is essential for designing the targeted, robust and durable solutions needed to reduce pollution. That’s the next step, but we have to collect the data first to make London a safer place for kids and people of all ages to live.

What will you do if you find a pollution “hotspot?”

When the Breathe London monitoring network identifies a likely hotspot, the relevant local authorities (the Greater London Authority, borough council or other) can perform further testing as needed, and then take action via immediate remediation or a longer term policy solution.

What can this data be used for?

Analysis of data from this project can be used to assess and inform new policies and other solutions for reducing air pollution. The Breathe London project team plans to use a combination of stationary and mobile monitoring data along with air quality models to:

  • Provide baseline data to paint a clearer picture of air pollution across London.
  • Provide information on sources and what is driving air pollution concentrations across the city.
  • Measure air pollution within and outside central London before and after the implementation of the Ultra Low Emission Zone (ULEZ), in order to help assess the effectiveness of this flagship policy from the Mayor.
  • Improve London’s current air quality models, providing a more accurate picture of the pollution Londoners are exposed to throughout the day.
  • Improve the ability to forecast episodes of high pollution; design policies that respond to these episodes, such as tighter controls on fossil fuel burning or restrictions on access to urban areas for polluting vehicles.

Data from the Breathe London project could also be used in a variety of other ways to assess and improve air quality. Some examples include:

  • Measure the impacts of a variety of policy interventions – including School Streets street closures, low-emission neighborhoods, low-emission bus zones and others.
  • Inform air quality plans to help local authorities and schools in the most polluted areas reduce pupils’ exposure to hazardous pollution.
  • Support development of planning policy to ensure new schools and other buildings used by vulnerable populations are not located in areas of poor air quality.
  • Inform controls on air pollution from construction sites and other sources.
  • Highlight the areas where new interventions are needed most.
  • Improve clean air route mapping and transport choices.

How can I find out more about the Ultra Low Emissions Zone (ULEZ)?

Introduced in April 2019, the ULEZ charges most older vehicles – which have less efficient engines and pollute more – extra to enter Central London. The ULEZ builds on London’s existing efforts to curb traffic and improve air quality, including the congestion charge that was introduced in 2003. Learn more.

What does an air quality alert mean and what health advice should I follow?

The air quality alerts provided on our map are based on forecasts of expected air quality produced by CERC’s ADMS-Urban air quality model. These alerts use Defra’s Daily Air Quality Index (DAQI) which tells you about levels of air pollution and provides recommended actions and health advice.

The Breathe London map incorporates air quality alerts that show forecasts for tomorrow and the day after for each London borough. You can also sign up here to receive these free airTEXT alerts and forecasts.

The alerts are separated into different levels (including ‘no alert’, ‘moderate’, ‘high’ and ‘very high’) based on the highest concentration of five different air pollutants: Nitrogen Dioxide (NO2), Particulate Matter (PM10), fine Particulate Matter (PM2.5), ozone and Sulphur Dioxide (SO2).

Air quality alerts are designed to help ensure you can plan ahead and, if possible, reduce your exposure. If you suffer from a medical condition, like asthma, which can be made worse by air pollution, these alerts also provide some notice so that you may have any necessary medication at hand. The air pollution levels and health advice shown in the table below are based on Defra’s DAQI and provide two sets of advice, one for at-risk individuals* and the other for the general public.

The 3 steps below are recommended to use the DAQI.

Step 1: Determine whether you (or any children or adults under your care) are likely to be at-risk from air pollution. You may find more information here and your doctor may be able to give you advice.

Step 2: If you may be at-risk, and are planning strenuous activity outdoors, check the air pollution forecast.

Step 3: Use the health messages in the table below corresponding to the highest forecast level of pollution as a guide.

Air Pollution Level Accompanying health messages for at-risk individuals* Accompanying health messages for the general population
No alert Enjoy your usual outdoor activities. Enjoy your usual outdoor activities.
Moderate Adults and children with lung problems, and adults with heart problems, who experience symptoms, should consider reducing strenuous physical activity, particularly outdoors. Enjoy your usual outdoor activities.
High Adults and children with lung problems, and adults with heart problems, should reduce strenuous physical exertion, particularly outdoors, and particularly if they experience symptoms. People with asthma may find they need to use their reliever inhaler more often. Older people should also reduce physical exertion. Anyone experiencing discomfort such as sore eyes, cough or sore throat should consider reducing activity, particularly outdoors.
Very High Adults and children with lung problems, adults with heart problems, and older people, should avoid strenuous physical activity. People with asthma may find they need to use their reliever inhaler more often. Reduce physical exertion, particularly outdoors, especially if you experience symptoms such as cough or sore throat.

*Adults and children with heart or lung problems are at greater risk of symptoms. Follow your doctor’s usual advice about exercising and managing your condition. It is possible that very sensitive individuals may experience health effects even on “no alert” air pollution days.

Long-term effects of air pollution

While the air pollution alerts and health advice above are geared towards the effects from short-term exposure to high levels of pollution, it is important to note that long-term exposure to air pollution can cause chronic conditions which may lead to reduced life expectancy. You may find more information on the long-term health effects of air pollution in the 2018 Guidance published by Public Health England.

Community action

Can I have a monitor in my neighborhood?

Unfortunately, the project locations have already been selected and it is not possible at this stage to add any additional monitors.

Contact hello@breathelondon.edf.org for more information.