Air pollution monitoring: Automatic, Urban and Rural Network (AURN)
How to get air pollution data from the AURN and the pollutants it measures.
The AURN is the UK’s largest automatic air pollution monitoring network. It provides accurate, high resolution, near-real time data at hourly intervals.
AURN sites meet the strict requirements of The Air Quality Standards Regulations (2010).
Find AURN monitoring stations
There are currently 207 AURN monitoring stations across the UK. Find your nearest AURN monitoring station.
Locations change when stations are:
- added where more monitoring is needed
- removed where monitoring is no longer needed or no longer possible
Monitoring stations are sometimes temporarily inactive because of faults or essential maintenance.
View air pollution data from the AURN
Go to Get air pollution data to view and download data from the AURN.
Go to Check air quality to view current air pollution levels.
Types of site included in the AURN
The AURN monitors air pollution at the following types of site:
- rural background
- rural industrial
- urban background
- urban industrial
- urban traffic
- suburban background
How these site types are classified is explained in the AURN site metadata assessment.
Pollutants the AURN measures
The AURN measures:
- fine particulate matter (PM2.5) (hourly measured, daily measured, uncorrected)
- particulate matter (PM10) (hourly measured, daily measured, uncorrected)
- nitrogen dioxide (NO2)
- nitrogen oxides (NOx) as NO2
- nitric oxide (NO)
- ozone (O3)
- sulphur dioxide (SO2)
- carbon monoxide (CO)
Data is available until 2023 for:
- volatile and non-volatile PM2.5 (hourly measured)
- volatile and non-volatile PM10 (hourly measured)
You can get modelled data for wind direction, wind speed and air temperature at AURN stations on Openair. Openair is a tool that analysts can use to analyse, interpret and understand air pollution data.
How AURN data is used
AURN data is used to:
- check air pollution levels
- do research and analysis
- check compliance with air quality targets and legal standards
- provide air quality information to the public
- provide information for air quality reviews and assessments
- assess long-term trends in air pollution in our air quality statistics
- create air pollution forecasts
- assess if air pollution controls are effective
- develop policies to protect human health and ecosystems
When the AURN started
The AURN started in 1998. It brought together the UK’s existing automatic urban and rural air quality monitoring networks to form a single national network.
This is why some monitoring stations within the AURN have data records going back to 1 July 1972.
How the AURN measures data
The AURN uses:
- BAM (beta attenuation monitors) and FIDAS (fine dust analysis system) with optical light scattering to measure hourly particulate matter (PM2.5 and PM10)
- gravimetric monitors to measure daily particulate matter (PM2.5 and PM10)
- chemiluminescence to measure nitric oxide (NO) and nitrogen dioxide (NO2)
- UV photometry and absorption to measure ozone (O3)
- UV fluorescence to measure sulphur dioxide (SO2)
- NDIR (non-dispersive infrared) absorption to measure carbon monoxide (CO)
How data is checked and verified
The AURN publishes provisional data every hour on Get air pollution data, which is then checked and verified.
Provisional data
Provisional AURN data is automatically published every hour. It’s marked with an ‘unverified’ flag.
The provisional data is automatically screened to exclude any data that’s faulty. These initial checks are very rapid.
After the provisional data is published it goes through full quality control and assurance checks. The data is updated if new information is found.
Any updates to the data are automatically uploaded to Get air pollution data (still marked as ‘unverified’).
Quality control and assurance
Quality control and assurance includes:
- a manual review to exclude any data from faulty instruments or calibrations
- checks for missing data
- data scaling (when numerical features in a dataset are transformed to a common scale so that no single feature dominates an algorithm)
- detailed manual checks every 3 months
The data is also independently audited to UK national and international gas calibration standards. This spots problems like:
- long-term drift in ozone instrument calibration
- faulty (NOx) converters
- drifts in concentrations in the calibration cylinder
- instrument leaks or flow faults
- faulty instrument configuration
- baseline correction for PM2.5 and PM10 where the analyser’s zero response is higher than 3µg m3 (micrograms per cubic meter)
Verified (ratified) data
Data is fully verified for the previous calendar year by 1 June.
Data is only verified after full quality control and assurance checks and a review by an experienced air quality consultant.
The consultant considers:
- the relationships between pollutants
- the impact of air pollution events
- the context of the data in the UK pollution climate
- national and regional pollutant patterns
- long-term trends
When all the checks and corrections are complete the data is reloaded to Get air pollution data with a ‘verified’ flag.
The Quality assurance and quality control procedures for UK air quality monitoring report has more information on data quality requirements for all pollutants.
Changes to verified data
Sometimes data is changed after it’s been verified. For example, if:
- a quality control and assurance audit or investigation has found a problem
- long-term analysis has found an anomaly between expected and measured trends
- research shows that new or tighter quality controls and checks are needed to meet data quality objectives
Search for changes to verified (ratified) data.
Latest AURN annual technical report
View the AURN annual technical report 2024.