Accredited official statistics

Summary

Updated 27 June 2025

Accredited Official Statistics

Air quality statistics in the UK, 1987 to 2024 - Summary

Updated 26th June 2025

1. Summary

This summary provides a selection of the key information from the full publication, ‘Air quality statistics’. This publication contains statistics which help describe the trends in concentrations of five air pollutants using a variety of metrics for the period 1987 to 2024. Data comes exclusively from the Automatic Urban and Rural Network (AURN), one of the UK’s air quality monitoring networks. The latest monitoring data is available from the UK-AIR website which also contains information about monitoring networks for other UK air pollutants.

The full publication is available here: Air quality statistics in the UK.

Information on the trends in concentrations of specific pollutants are available from the following links:

Air quality statistics in the UK, 1987 to 2024 – Nitrogen dioxide

Air quality statistics in the UK, 1987 to 2024 – Particulate matter (PM10 and PM2.5)

Air quality statistics in the UK, 1987 to 2024 – Ozone

Air quality statistics in the UK, 1987 to 2024 – Days with ‘Moderate’ or higher air pollution (includes sulphur dioxide)

The data used in this publication can be found in the accompanying tables.

Please email us with your feedback to help us make the publication more valuable to you: aqie.correspondence@defra.gov.uk

2. Future Changes

From 2026, the particulate matter section of this publication will include an assessment of progress towards the targets for reducing concentrations of and population exposure to PM2.5 as set out in the Environmental Targets (Fine Particulate Matter) (England) Regulations 2023. More information on these targets is included in the particulate matter section.

3. Contact

Enquiries to: aqie.correspondence@defra.gov.uk

Tel: 03459 33 55 77 (Defra enquiries)

Lead analyst: Neil Ward

Production team: Alex Mouatt, Joseph Grealy, Mohamed Ghalaieny

You can also contact us via X (formerly Twitter): @DefraStats

Air Quality Statistics team,

Department for Environment, Food and Rural Affairs,

Seacole Building,

2 Marsham Street,

London

SW1P 4DF

4. Nitrogen dioxide (NO2)

• Urban background and roadside nitrogen dioxide (NO2) pollution has shown long-term improvement.

• In 2024, annual mean concentrations of NO2 showed a decrease of 8 per cent at urban background sites and a decrease of 6 per cent at roadside sites from 2023 levels.

• In 2024, the number of hours of ‘Moderate’ or higher NO2 pollution at roadside sites remained similar to 2023, which was the lowest in the time series. Overall there has been a reduction in short-term ‘Moderate’ or high NO2 pollution since 2007, mainly due to reductions in this measure at monitoring sites in London.

• In 2024, as in previous years, NO2 pollution tended to peak in the rush hours and during weekdays, particularly for roadside sites. Concentrations at roadside sites in 2024 were 23 per cent greater during the working week compared to the weekend. This pattern of concentrations follows the daily and hourly trends in road traffic.

5. Particulate matter (PM10/PM2.5)

• Urban background and roadside particulate pollution (PM10 and PM2.5) has shown long-term improvement despite a period of relatively little change between 2015 and 2019.

• In 2024 annual mean concentrations of PM2.5 at urban background showed a decrease of 1 per cent and roadside sites showed a decrease of 3 per cent compared to 2023, reaching the lowest levels recorded.

• In 2024, annual mean concentrations of PM10 for both urban background and roadside locations showed a decrease of 4 per cent, reaching the lowest levels recorded.

• The number of hours of ‘Moderate’ or higher levels of particulate matter (PM10/PM2.5) pollution has reduced in the long term. In 2024, the number of hours of ‘Moderate’ or higher pollution recorded was the lowest in the time series for both PM2.5 urban background and roadside as well as for both PM10 urban background and roadside.

• In 2024, the highest monthly mean concentrations of PM2.5 in urban areas tended to occur during the spring and late autumn.

• Residential combustion of wood and coal in stoves and open fires is a large contributor to emissions of particulate matter both in the UK, and across Europe, and is a large contributor towards elevated concentrations in late autumn and winter months and during the evenings.

• A peak in early spring is typical for PM2.5 concentrations, as elevated concentrations of nitrates are transported from agricultural operations across continental Europe.

6. Ozone (O3)

• Ozone is a secondary pollutant, it is created in the air, in the presence of sunlight, from the reactions of its precursors, nitrogen oxides (NOx) and volatile organic compounds (VOCs). The formation of ozone is sensitive to changes in the balance of its precursor compounds and to levels of sunlight.

• Urban background concentrations of O3 have shown a long-term increase of 66 per cent since 1992, this is mostly driven by local level changes in the balance of ozone production and removal from the air in addition to high ozone concentrations across the northern hemisphere. Rural background ozone pollution has shown a slow increase of 8 per cent since 2012.

• In 2024 concentrations at urban background sites showed a decrease of 1 per cent from 2023, but was the second highest value in the time series. Rural background sites showed a decrease of 3 per cent from 2023.

• There were on average fewer hours of ‘Moderate’ or higher ozone pollution in 2024 compared with 2023 at both rural background and urban background sites. The number of hours of ‘Moderate’ or higher ozone pollution at both site types has been generally high since 2018, with the exception of 2021.

• Ozone pollution is strongly linked to hot, sunny conditions and prolonged instances of such conditions during the summers in most years since 2018 likely contributed to the higher incidences of ‘Moderate’ or higher ozone pollution observed during these periods.

• In 2024, concentrations of ozone at both urban and rural background sites built up over the first five months of the year, peaking in May, then decreasing in June and July. This was followed by a second lower peak in September. After this, concentrations of ozone decreased towards the lowest point in November before rising slightly again towards the end of the year.

7. Days with ‘Moderate’ or higher air pollution (includes sulphur dioxide in addition to the pollutants reported above)

• There were on average 6 days of ‘Moderate’ or higher pollution at urban pollution monitoring sites in 2024, down from 9 days in 2023.

• The number of days with ‘Moderate’ or higher air pollution at rural monitoring sites peaked in 2018. Levels have fluctuated since then, with noticeable drops in 2021 and 2024, when the number of days with 'Moderate' or higher air pollution fell to the lowest level since 2016.

• Since 2015 the mean number of days of ‘Moderate’ or higher pollution has been higher at rural sites than urban sites due to ozone pollution. There were on average fewer days of ‘Moderate’ or higher pollution at rural pollution monitoring sites in 2024 compared with 2023 (19 days in 2023, 11 days in 2024).

• In 2024, as in previous years, ozone was responsible for a large proportion of the ‘Moderate’ or higher pollution days at rural sites. The increase in ozone pollution in most years since 2018 was in part due to the prolonged hot and sunny conditions experienced in the UK in the summer of these years.

8. Sections in this release

Background to concentrations of air pollutants

Concentrations of nitrogen dioxide

Concentrations of particulate matter (PM10 and PM2.5)

Concentrations of ozone

Days with ‘Moderate’ or higher air pollution (includes sulphur dioxide)

Compliance with the Code of Practice for Statistics and Defra group Statistics quality principles, and recent changes to the publication

Statistical tables (ENV02 – Air quality statistics)