Accredited official statistics

Summary

Updated 18 March 2025

Accredited Official Statistics

Air quality statistics in the UK, 1987 to 2023 - Summary

Updated 30th April 2024

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 2023. Data come from the Automatic Urban and Rural Network (AURN), one of the UK’s air quality monitoring networks. The latest monitoring data are 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, 1990 to 2023 – Nitrogen dioxide

Air quality statistics in the UK, 1992 to 2023 – Particulate matter (PM10 and PM2.5)

Air quality statistics in the UK, 1987 to 2023 – Ozone

Air quality statistics in the UK, 2010 to 2023 – Days with ‘Moderate’ or higher air pollution (includes sulphur dioxide)

The data used in this publication can be found in the accompanying tables. Modelled data from Pollution Climate Mapping (PCM) which estimates concentrations across the entirety of the UK are published in the autumn and are not included in this publication.

Please email us with your feedback, or respond to this short survey, to help us make the publication more valuable to you: AQIE.Correspondence@defra.gov.uk

2. Contact

Enquiries to: AQIE.Correspondence@defra.gov.uk

Tel: 03459 33 55 77 (Defra enquiries)

Lead statistician: Ellie Martell

Production team: Alex Mouatt, Neil Ward, Anes Motam

You can also contact us via Twitter:@DefraStats

Air Quality Statistics team,

Department for Environment, Food and Rural Affairs,

Seacole Building,

2 Marsham Street,

London

SW1P 4DF

3. Nitrogen dioxide (NO2)

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

• In 2023, annual mean concentrations of NO2 showed a decrease of 9 per cent at urban background sites and a decrease of 7 per cent at roadside sites from 2022 levels.

• In 2023, the number of hours of ‘Moderate’ or higher NO2 pollution at roadside sites was the lowest in the time series. This continues a decling trend since measurements began, that is largely the result of tighter emission standards for road vehicles, and the switch away from burning coal for power generation.

• In 2023, 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 2023 were 18 per cent greater during the working week compared to the weekend. This pattern follows the daily and hourly trends in road traffic.

• Nitrogen dioxide is a gas mainly produced during the combustion of fossil fuels.

4. Particulate matter (PM10/PM2.5)

• Urban background and roadside particulate pollution (PM10 and PM2.5) has shown long-term improvement despite a period of little change between 2015 and 2023.

• In 2023 annual mean concentrations of PM2.5 at both urban background and roadside sites showed a decrease of 12 per cent, reaching the lowest levels recorded.

• In 2023, annual mean concentrations of PM10 showed a decrease of 12 per cent for urban background and a decrease of 10 per cent for roadside locations, 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 2023, 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 PM10 urban background. For PM10 roadside the number of hours was only slightly higher than the lowest recorded in 2021.

• In 2022, the highest concentrations of PM2.5 in urban areas tended to occur during the spring and winter months.

• Domestic 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 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 UK and continental Europe (e.g., from fertilisers) - see the Air Quality Expert Group report. Although in 2023 there was also a notable peak in September, which coincided with a heatwave across the UK.

5. Ozone (O3)

• Urban background concentrations of O3 have shown a long-term increase, partly due to reductions in other pollutants which limit ozone concentrations. In 2023 urban background concentrations showed an increase of 3 per cent from 2022 reaching 66.8 µg/m3 which is the highest value in the time series. Rural background ozone pollution has shown a slow increase since 2016.

• There were on average fewer hours of ‘Moderate’ or higher ozone pollution in 2023 compared with 2022 at rural background sites, and slightly more hours on average at 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 linked to hot, sunny conditions and the 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 2023, concentrations of ozone at both urban and rural background sites built up over the first few months of 2021, peaking in June then sharply decreasing in July followed by a second lower peak in September. After this, concentrations decreased towards their lowest point in November before rising slightly again towards the end of the year.

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

• There were on average 9 days of ‘Moderate’ or higher pollution at urban pollution monitoring sites in 2023, similar to 2022.

• Since reaching the highest value in the time series in 2018, the number of days of ‘Moderate’ or higher air pollution at rural monitoring sites has remained comparatively high but shows no clear trend.

• 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 2023 compared with 2022 (22 days in 2022, 19 days in 2023).

• In 2023, as in previous years, ozone was responsible for a large proportion of the ‘Moderate’ or higher pollution days. An 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 summers of these years.

7. 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)