A3: Concentrations of fine particulate matter (PM2.5) in the air
Short Description
This indicator is an assessment of clean air (reporting the condition of the atmosphere as an asset). It measures the level of people’s long-term exposure to airborne fine particulate matter (PM2.5). Long-term exposure to particulate matter contributes to the risk of developing diseases such as cardiovascular disease and lung cancer. The main sources of PM2.5 pollution are combustion in the residential, public and commercial sectors; industrial processes; road transport and agriculture.
The Environmental Targets (fine particulate matter) (England) Regulations 2023 set 2 targets for PM2.5 in England to be met by the end of 2040. One, is a minimum level of reduction in the average concentration people are exposed to. The other, is a maximum concentration level which should not be exceeded. Both targets are based on measurements of PM2.5 concentrations taken at national monitoring sites throughout England. Interim targets for 2028 were published in the Environmental Improvement Plan 2023.
Readiness and links to data
This indicator has been revised in the 2025 update of the Outcome Indicator Framework. The new data, presented here for the first time in 2025, are published annually on the PM2.5 Targets (PERT and AMCT) page of the UK-AIR website. These data are used to assess compliance with the Population Exposure Reduction Target (PERT) and the Annual Mean Concentration Target (AMCT) for PM2.5, although the assessments used to monitor progress towards the former (see Methodology for calculating progress towards the PM2.5 targets) differ from the trend assessments reported in this indicator.
The PM2.5 data used to update this indicator in previous years up to and including 2024, continue to be published annually at UK Air Information Resource, Modelled background pollution data.
Notes on indicator
Population exposure to PM2.5 is represented by the population exposure indicator (A3i), calculated using measurements of annual mean concentrations of PM2.5 at representative Automatic Urban and Rural Network (AURN) monitoring sites. The monitoring sites are spread geographically across England, they reflect population density and are located in areas where concentrations are typical of where most people in that region live. Monitoring sites characterised as ‘urban background’ (and, in some instances, ‘suburban background’) meet these criteria. Other considerations, such as representing areas of deprivation, are also taken into account when establishing new sites. This enables the indicator to account for most of the population living in densely populated urban areas, where concentrations are likely to be greatest.
The calculation approach (see Methodology for calculating progress towards the PM2.5 targets) incorporates a statistical method recommended by experts to account for the large change in the number of PM2.5 monitoring sites expected as a result of the ongoing expansion of the AURN. A decrease in the population exposure indicator represents a reduction in the risk to the nation’s health from PM2.5.
The annual mean concentration of PM2.5 (A3ii) indicates the concentration at a particular location, and it varies from year-to-year due to a range of factors such as weather conditions, as well as pollutant emissions. A reduction in the maximum annual mean concentration measured and a reduction in the number of locations above the annual mean concentration target shows that concentrations are reducing in the areas where they are the highest.
Indicator components
Figure A3i: Population exposure to fine particulate matter (PM2.5) in England, 2018 to 2023
Table A3i: Population exposure to fine particulate matter (PM2.5) in England, 2018 to 2023
| Year | Value |
|---|---|
| 2018 | 10.09 |
| 2019 | 10.02 |
| 2020 | 9.41 |
| 2021 | 8.68 |
| 2022 | 8.11 |
| 2023 | 7.86 |
Trend description for A3i
The population exposure indicator for PM2.5 in England has fallen from 10.1 micrograms per cubic metre (μg per m3) in 2018 to 7.9 μg per m3 in 2023, a decrease of 2.2 μg per m3, or 22.1% over the latest 5 years for which data are available.
Assessment of change
Concentrations of PM2.5 have shown a decrease (improvement) over the short-term assessment period. The time series is not yet long enough to make a trend assessment over the medium and long-term time periods. This assessment does not consider whether these improvements are on a sufficient scale for meeting any targets; however, information on how the data in this indicator are used to measure progress towards the Environment Act PM2.5 targets can be found on the UK-Air website.
Change since 2018 has also been assessed, and in this instance, both the baseline year and the results for this assessment (an improvement) are the same as those for the short-term assessment.
Further information on this assessment, along with details on the methodology, is provided in the Assessment background page. Summaries by 25 Year Environment Plan goal and information on indicator links are presented in the Assessment results pages.
Table A3i: Assessment of change
| Component | Period | Date range | Percentage change | Smoothing function | Assessment of change |
|---|---|---|---|---|---|
| A3i | Short term | 2018 to 2023 | -22.10 | Moving average data | Improvement |
| A3i | Medium term | N/A | N/A | N/A | Not assessed |
| A3i | Long term | N/A | N/A | N/A | Not assessed |
Note that percentage change refers to the difference seen from the first to last year in the specified date range. Assessment results presented here may differ from those used to monitor progress towards the PERT (see PM2.5 Targets (PERT and AMCT)) because the latter accounts for changes in the number of monitoring sites over time, whereas the former does not.
Figure A3ii: Concentrations of fine particulate matter (PM2.5) at AURN monitoring sites in England, 2011 to 2023
Table A3ii: Concentrations of fine particulate matter (PM2.5) at AURN monitoring sites in England, 2011 to 2023
| Year | 4 µg/m3 | 5 µg/m3 | 6 µg/m3 | 7 µg/m3 | 8 µg/m3 | 9 µg/m3 | 10 µg/m3 | 11 µg/m3 | 12 µg/m3 | 13 µg/m3 | 14 µg/m3 | 15 µg/m3 | 16 µg/m3 | 17 µg/m3 | 18 µg/m3 | 19 µg/m3 | 20 µg/m3 | 21 µg/m3 | 24 µg/m3 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2009 | - | - | - | - | - | 3 | 1 | 4 | 5 | 6 | 8 | 2 | 1 | - | 1 | - | - | - | - |
| 2010 | - | - | - | - | - | 4 | 3 | 3 | 1 | 5 | 7 | 4 | 4 | 4 | - | 1 | - | - | - |
| 2011 | - | - | - | - | - | - | 2 | 2 | 5 | 3 | 6 | 3 | 10 | 3 | - | 2 | - | - | 1 |
| 2012 | - | - | - | - | - | 1 | 4 | 8 | 5 | 8 | 6 | 4 | 5 | 2 | 1 | - | - | 1 | - |
| 2013 | - | - | - | - | - | 4 | 4 | 5 | 8 | 8 | 6 | 4 | 3 | 1 | 1 | - | 1 | - | - |
| 2014 | - | - | - | - | 1 | 2 | 2 | 5 | 8 | 7 | 7 | 3 | 1 | - | 1 | - | - | - | - |
| 2015 | - | - | - | 5 | 1 | 6 | 16 | 11 | 9 | 1 | - | 1 | 1 | - | - | - | - | - | - |
| 2016 | - | - | - | 2 | 3 | 5 | 13 | 10 | 11 | 2 | - | 1 | 1 | - | - | - | - | - | - |
| 2017 | - | - | - | 6 | 5 | 11 | 8 | 13 | 4 | - | 1 | 1 | 1 | - | - | - | - | - | - |
| 2018 | - | - | - | 1 | 3 | 13 | 14 | 9 | 6 | 1 | 1 | 1 | 1 | - | - | - | - | - | - |
| 2019 | - | - | - | - | 6 | 14 | 14 | 13 | 7 | 1 | 2 | 1 | - | - | - | - | - | - | - |
| 2020 | - | - | 1 | 11 | 25 | 11 | 6 | 2 | 1 | - | - | - | - | - | - | - | - | - | - |
| 2021 | - | - | 1 | 16 | 17 | 11 | 2 | 2 | 2 | 1 | - | - | - | - | - | - | - | - | - |
| 2022 | - | - | - | 6 | 19 | 18 | 6 | 4 | 2 | - | - | - | - | - | - | - | - | - | - |
| 2023 | 1 | 1 | 9 | 28 | 24 | 6 | 4 | - | 1 | - | - | - | - | - | - | - | - | - | - |
Trend description for A3ii
Trends for each monitoring site vary, but in general concentrations have been decreasing at the majority of sites. In 2009, the highest annual average concentration of PM2.5 at an English AURN site that met the required data capture threshold was 18 micrograms per cubic metre (µg per m3) and 13% of sites (4 individual AURN sites) were equal to or below the 10 µg per m3 annual mean concentration target. By 2023, the highest measured annual mean concentration of PM2.5 at an English AURN site had fallen to 12 µg per m3 and 99% of sites (73 individual sites) were equal to or below the target. This is equivalent to a 6 µg per m3 (33%) reduction in the highest recorded concentrations of PM2.5 over the 14 years for which data are available.
Assessment of change
No assessment of change was undertaken for this indicator component as it is based on the same underlying data that are already assessed in A3i.