About this data

Source: Defra, Air quality statistics in the UK, 1987 to 2025

• Measurements come from the Automatic Urban and Rural Network (AURN), the UK's highest-quality network of air quality monitoring stations. Each line is the average across all stations of that type that met the data capture threshold that year.
• Roadside stations sit close to busy roads; urban background stations are in towns and cities away from direct traffic; rural background stations are in the countryside.
• The number of stations changes over time, and grew sharply in 2025 as the network was expanded, which can affect the averages from one year to the next.
• PM2.5 has been measured consistently since 2009 and PM10 since 1992. Ozone is not measured at roadside stations, and particulate matter has too few rural stations for a reliable average.
• The legal limit for nitrogen dioxide is the annual average limit value in the Air Quality Standards Regulations 2010. The PM2.5 target is set in the Environmental Targets (Fine Particulate Matter) (England) Regulations 2023 and applies to every monitoring station in England.

This chart appears in Air pollution.