How air pollution is monitored in the UK
Air pollution monitoring networks and how they measure air pollution in the UK.
The Department for Environment, Food and Rural Affairs (Defra) monitors air pollution to:
- understand what pollutants are in the air and how levels change over time
- provide the public with air quality forecasts and air pollution data
- inform policies to protect human health and the environment
These are legal requirements in the:
- Air Quality standards Regulations 2010
- Environmental Targets (Fine Particulate Matter) (England) Regulations 2023
How air pollution is monitored
Air pollution levels are recorded by monitoring stations that measure pollutants in outdoor (ambient) air. The monitoring stations are part of national monitoring networks that measure different air pollutants.
The Environment Agency manages the UK’s national monitoring networks for Defra and the devolved governments in Northern Ireland, Scotland and Wales.
Defra will add other monitoring networks to this page during 2026.
Defra's near real-time, automatic data
Automatic networks use instruments that operate continuously. They produce frequent measurements, often every hour. These measurements:
- support long-term analysis
- show whether air quality standards and targets are being met
- allow data from across the UK to be managed consistently, using agreed methods and quality checks
Automatic networks publish provisional data every hour on the Get air pollution data service, which is then checked and verified.
The Automatic Urban and Rural Network is the UK’s largest automatic air pollution monitoring network.
Defra’s near real-time, automatic monitoring networks
Defra's non-real-time, non-automatic data
Non-automatic networks do not automatically publish data. Some non-automatic networks use instruments that operate continuously, but their data is collected and processed differently to automatic networks.
Monitoring stations in these networks gather air pollution samples in a filter, tube or bottle which Defra collects and takes to a laboratory for analysis. This happens weekly, fortnightly, monthly or quarterly. Defra publishes the data after analysis on the Get air pollution data service.
Defra’s non-automatic air pollution monitoring networks:
- provide trends for pollutants that are best measured over weeks, months or years, because levels change slowly
- monitor pollutants that cannot easily be measured using automatic instruments
- monitor pollutants that need specialist chemical analysis or processing (for example, heavy metals and polycyclic aromatic hydrocarbons)
- complement automatic data by providing information from different locations
Defra will add more non-automatic monitoring networks to this page during 2026.