Air quality monitoring is an essential tool for understanding air pollution, tracking trends, and understanding the impacts of policy action taken to improve air quality.

London has one of the most comprehensive air quality monitoring networks of any city in the world with over 100 reference grade air quality monitoring sites and over 1800 passive diffusion tubes, managed by the London boroughs, along with the Breathe London Network. The reference sites provide accurate continuous air quality monitoring data which is crucial for research and regulatory reporting.

The Breathe London Network aims to make air quality monitoring and reliable air quality data accessible by providing a lower-cost, easy-to-install and maintain, alternative for monitoring air quality in London, to supplement the existing essential reference monitoring network.

The network

The Breathe London network is run by the Environmental Research Group at Imperial College London - the same group that run the London Air Quality Network. The group combines air pollution science, toxicology and epidemiology to determine the impacts of air pollution on health and has over 20 years of experience running large urban air quality monitoring networks.

Breathe London network is a high-density network of multi-parameter sensor nodes; combining aerosol and physico-chemical sensor capability. The network consists of over 600 measurement locations within Greater London. It is a hybrid approach, where data from selected high-resolution reference monitoring sites are used to improve the accuracy of a larger network of low-cost sensor nodes.

The measurements are used to characterise pollutant levels and their variability, in order to assess local variations, as well as to demonstrate operational network approaches in complex environments.

The data

All the data from the Breathe London network is publicly available in near real-time on the Breathe London website. The website provides a map of current air quality, graphs for each site and enables the hourly data for each site to be downloaded for all to use. An application programming interface (API) is available for developers/researchers to access the data directly.

The programme empowers communities by enabling them to monitor air pollution in their neighbourhoods and use the data to lobby for change.

Quality assurance and quality control

The Environmental Research Group has developed a unique two-stage calibration and correction procedure. The sensors have complex and interdependent responses to changes in real-world atmospheric composition and conditions that require ongoing analysis to correct for.

This calibration method is specifically designed to react to changes throughout the lifetime of the network deployment.


The Breathe London Network is providing local, reliable and accurate air quality data to communities across London. The network has grown rapidly since its launch in 2021, from 136 initial sites to now over 600 in two years. The breadth of partner organisations makes the network unique, including schools, hospitals, boroughs, cultural institutions, and community groups.

Breathe London shows that as a hybrid network it is a paradigm shift in air quality monitoring and one which we hope will serve as a blueprint for cities around the world - changing the way Air Quality is monitored globally.

I’d like to join the network, what do I do?

There are two ways to join the network:

For groups, individuals and organisations with funding, you can head straight to the Breathe London Shop.

Alternatively, the Breathe London Community Programme is open for groups to apply for up to 60 fully funded Nodes over the next three years.