Air pollution in the UK 2024: compliance assessment summary
Published 30 September 2025
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1. Executive summary
The UK’s Air Quality Standards Regulations (2010) and the Environment Act (2021) require reporting of compliance and progress made on an annual basis. These data are reported on behalf of the Department for Environment, Food and Rural Affairs (Defra) and the Devolved Administrations of Scotland, Wales and Northern Ireland.
This compliance assessment summary has been prepared to accompany and summarise the UK’s submission on air quality compliance in 2024. It presents a summary of the UK’s compliance with The Air Quality Standards Regulations (2010), based on measurements from national air pollution monitoring networks and supplementary assessment (which includes air pollution modelling).
It includes details of the exceedances of air quality limit values and target values reported in 2024, and a comparison with previous years since 2008. It also presents progress made towards the new PM2.5 targets set in the Environmental Targets (Fine Particulate Matter) (England) Regulations (2023).
This document is an extract from a larger report, ‘Air pollution in the UK 2024’, which, in addition to the compliance summary, also provides background information on the pollutants covered by the above legislation; their sources, effects, how they are measured and modelled in the UK, and details of their spatial distribution and changes over time. The pollutants covered in the main report are:
- nitrogen oxides (NOX) comprising NO and NO2
- PM10 and PM2.5 particulate matter
- ozone (O3)
- sulphur dioxide (SO2)
- carbon monoxide (CO)
- benzene
- 1,3-butadiene
- metals: lead, cadmium, nickel and mercury, and the metalloid arsenic
- benzo[a]pyrene.
For the purposes of air quality monitoring and assessment of compliance with The Air Quality Standards Regulations (2010), the UK is divided into 43 zones. The 2024 results are detailed in section 4 of this report and summarised below:
- the UK met the limit value for hourly mean nitrogen dioxide (NO2) in all 43 zones
- 38 zones met the limit value for annual mean NO2, with five zones exceeding
- all zones required to meet the critical level for annual NOX set for protection of vegetation (non-agglomeration zones) did so. This has been the case since 2008
- all zones met the limit value for daily mean concentration of PM10 particulate matter, without the need for the subtraction of the contribution from natural sources
- all zones met the limit value for annual mean concentration of PM10 particulate matter, without the need for the subtraction of the contribution from natural sources
- all zones met the limit value for annual mean concentration of PM2.5 particulate matter. Subtraction of natural source contribution is not allowed in the case of PM2.5
- the UK continues to meet its 2020 national exposure reduction target for PM2.5, based on the Average Exposure Indicator (AEI) statistic (explained in Section 4 of this report). In 2024, the three-year running mean AEI was 7 µg m-3; this statistic has therefore remained within the National Exposure Reduction Target (which was for the AEI to reduce to 11 µg m-3 by 2020)
- the Environmental Targets (Fine Particulate Matter) (England) Regulations (2023) set a legally mandatory target of 10 µg m-3 for annual mean PM2.5 concentrations to be achieved in England by 2040. Legal compliance is assessed using measurements from monitoring stations in England of all site types. One monitoring station in England exceeded this target in 2024 (London Marylebone Road, a roadside site in central London). However, in 2024 no monitoring stations exceeded the interim target of 12 µg m-3, to be met by January 2028
- the Environmental Targets (Fine Particulate Matter) (England) Regulations (2023) also set a legally mandatory PM2.5 Population Exposure Reduction Target (PERT) of 35% compared to 2018 to be achieved in England by 2040. An interim target of 22% is to be met by January 2028. The population exposure value for 2024 was 7.56 µg m-3, which constitutes a reduction of 25% from the 2018 value. Therefore in 2024 England met the interim PERT of 22%
- for ozone, there are two target values (which are being met) and two long term objectives (where there are exceedances)
- all zones met both the target value based on the daily maximum eight-hour mean, which was set for the protection of human health
- all zones met the target value based on the AOT40 statistic (explained in section 4 of this report), which was set for the protection of vegetation
- 12 zones out of 43 were compliant with the more stringent long-term objective for ozone, set for the protection of human health (31 zones exceeded). This is based on the daily maximum eight-hour mean
- 39 zones out of 43 were compliant with the more stringent long-term objective for ozone, set for the protection of vegetation (4 zones exceeded). This is based on the AOT40 statistic, which is explained in Section 4 of this report.
- there were no measured exceedances of the ozone population information threshold of 180 µg m-3 in 2024
- all zones met the limit values for sulphur dioxide, carbon monoxide, benzene and lead, and the target values for arsenic, cadmium
- 2024 was the first year in which all zones have been compliant with the target value for benzo[a]pyrene
- three zones out of 43 exceeded the target value for nickel
For more information on air quality in the UK go to the following sites:
- Department for Environment and Rural Affairs website
- UK Air Quality website
- Scottish air quality website
- Air quality Wales website
- Air quality Northern Ireland website
2. Introduction
Clean air is vital for people’s health and the environment, essential for making sure our cities are welcoming places for people to live and work now and in the future, and for our prosperity. Improving air quality remains a key priority for the UK. It is therefore important to monitor levels of air pollution.
In the UK, concentrations of a range of pollutants in ambient air are regulated by The Air Quality Standards Regulations (AQSR) (2010) as follows:
-
Air Quality Standards Regulations (2010) (UK Government, 2010) and in England their December 2016 amendment (UK Government, 2016)
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Air Quality Standards (Scotland) Regulations (2010) in Scotland (Scottish Government, 2010), and their December 2016 amendment (Scottish Government, 2016)
-
Air Quality Standards (Wales) Regulations (2010) in Wales (Welsh Government, 2010)
- Air Quality Standards Regulations (Northern Ireland) (2010) (Department of Environment Northern Ireland, 2010) and their January 2017 amendment (DAERA, 2017)
- Air Quality Standards Regulations (Gibraltar) and their December 2016 amendment (HM Government of Gibraltar, 2016)
These Regulations have their origins in the following European Union legislation:
-
Directive 2008/50/EC of 21 May 2008, on Ambient Air Quality and Cleaner Air for Europe (European Parliament and Council of the European Union, 2008)
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Directive 2004/107/EC of 15 December 2004 (European Parliament and Council of the European, 2004).
The AQSR (2010) set ‘limit values’, ‘target values’, ‘long-term objectives’ and ‘critical levels’ for ambient concentrations of pollutants. These are explained below, as well as provisions regarding monitoring, and reporting of data.
Limit values must not be exceeded. They are set for individual pollutants and comprise a concentration value, an averaging period for the concentration value, a number of exceedances allowed (per year) and a date by which this must be achieved. Some pollutants have more than one limit value, for example relating to short-term average concentrations (such as the hourly mean) and long-term average concentrations (such as the annual mean). The UK is legally required to meet the limit values.
Target values are set for some pollutants and are configured in the same way as limit values. The UK is legally required to take all necessary measures not entailing disproportionate costs to meet the target values.
For ozone, there are also Long-Term Objectives (LTOs) as well as target values. These are based on the same statistics as the ozone target values but are more stringent and have no specified date by when they should be met. As with target values, the UK is legally required to take all necessary measures not entailing disproportionate costs to meet the long-term objectives, but achievement is not legally mandatory.
Critical levels are thresholds set for annual mean and winter mean SO2 concentration in rural areas. These are intended for protection of ecosystems and are not applicable to built-up areas.
The AQSR (2010) includes detailed provisions on the monitoring and reporting of air quality, including:
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the division of the UK into zones for the purposes of compliance reporting
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the location and number of sampling points
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the measurement methods to be used
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data quality objectives
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the siting criteria each monitoring station must meet
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provision for reporting compliance
-
provision of information to the public.
The UK has statutory monitoring networks in place to meet the requirements of the above legislation, with air quality modelling used to supplement the monitored data where applicable.
In addition, concentrations of fine particulate matter are regulated by more recent legislation: the Environmental Targets (Fine Particulate Matter) (England) Regulations 2023 (UK Government, 2023). These regulations, which came into force in January 2023, set two new targets: for ambient concentrations of particulate matter measured as PM2.5, and for PM2.5 population exposure reduction over the period between 2018 and 2040.
The meaning of “targets” in this legislation is different to that of “target values” in the AQSR (2010). There is a legal requirement to meet the targets of the Environmental Targets (Fine Particulate Matter) (England) Regulations 2023 in England by the specified dates. In addition, legal compliance with these targets is assessed using measured pollutant concentrations from the Automatic Urban and Rural Network (AURN) only and modelling is not included in the assessment.
Further information on air quality monitoring in the UK can be found on Defra’s online UK Air Information Resource (UK-AIR).
3. Definition of zones
The UK is divided into 43 zones for air quality assessment. There are 28 agglomeration zones (large urban areas) and 15 non-agglomeration zones. Each zone has an identification code (Table 21).
Zones are shown in Figure 21.
Table 21: UK zones for Ambient Air Quality Reporting 2024
| Zone | Zone code | Zone type |
|---|---|---|
| Greater London Urban Area | UK0001 | Agglomeration |
| West Midlands Urban Area | UK0002 | Agglomeration |
| Greater Manchester Urban Area | UK0003 | Agglomeration |
| West Yorkshire Urban Area | UK0004 | Agglomeration |
| Tyneside | UK0005 | Agglomeration |
| Liverpool Urban Area | UK0006 | Agglomeration |
| Sheffield Urban Area | UK0007 | Agglomeration |
| Nottingham Urban Area | UK0008 | Agglomeration |
| Bristol Urban Area | UK0009 | Agglomeration |
| Brighton/Worthing/Littlehampton | UK0010 | Agglomeration |
| Leicester Urban Area | UK0011 | Agglomeration |
| Portsmouth Urban Area | UK0012 | Agglomeration |
| Teesside Urban Area | UK0013 | Agglomeration |
| The Potteries | UK0014 | Agglomeration |
| Bournemouth Urban Area | UK0015 | Agglomeration |
| Reading/Wokingham Urban Area | UK0016 | Agglomeration |
| Coventry/Bedworth | UK0017 | Agglomeration |
| Kingston upon Hull | UK0018 | Agglomeration |
| Southampton Urban Area | UK0019 | Agglomeration |
| Birkenhead Urban Area | UK0020 | Agglomeration |
| Southend Urban Area | UK0021 | Agglomeration |
| Blackpool Urban Area | UK0022 | Agglomeration |
| Preston Urban Area | UK0023 | Agglomeration |
| Glasgow Urban Area | UK0024 | Agglomeration |
| Edinburgh Urban Area | UK0025 | Agglomeration |
| Cardiff Urban Area | UK0026 | Agglomeration |
| Swansea Urban Area | UK0027 | Agglomeration |
| Belfast Metropolitan Urban Area | UK0028 | Agglomeration |
| Eastern | UK0029 | Non-agglomeration |
| South West | UK0030 | Non-agglomeration |
| South East | UK0031 | Non-agglomeration |
| East Midlands | UK0032 | Non-agglomeration |
| North West and Merseyside | UK0033 | Non-agglomeration |
| Yorkshire and Humberside | UK0034 | Non-agglomeration |
| West Midlands | UK0035 | Non-agglomeration |
| North East | UK0036 | Non-agglomeration |
| Central Scotland | UK0037 | Non-agglomeration |
| North East Scotland | UK0038 | Non-agglomeration |
| Highland | UK0039 | Non-agglomeration |
| Scottish Borders | UK0040 | Non-agglomeration |
| South Wales | UK0041 | Non-agglomeration |
| North Wales | UK0042 | Non-agglomeration |
| Northern Ireland | UK0043 | Non-agglomeration |
Figure 21: UK zones for Ambient Air Quality Reporting 2024
Crown copyright. All rights reserved Defra, Licence number 100022861 [2025].
4. Air Quality Assessment for 2024
The air quality assessment for compliance against The Air Quality Standards Regulations (AQSR) (2010) is derived from a combination of measured pollutant concentrations from the Automatic Urban and Rural Network (AURN) and other networks, together with supplementary assessment. Supplementary assessment can be modelling using the Pollution Climate Mapping (PCM) model, NO2 diffusion tube measurements from the UK Urban Nitrogen Dioxide Network (the UUNN), or objective estimation.
This is explained in Defra’s technical report on UK air quality assessment (Pugsley, K. L. et al., 2025). Where both measurements and supplementary assessment results are available for a zone, the assessment of compliance for each zone is based on the higher concentration of the two.
In the case of NO2, an additional rule was introduced in 2021. This is used where there is roadside monitoring (an AURN monitoring site, a UUNN diffusion tube monitoring site, or both) on a major urban road, which is also modelled by the PCM model. This rule determines the order of precedence of these data sources when used in compliance assessment and is described in the section below.
Compliance with the PM2.5 targets set in the Environmental Targets (Fine Particulate Matter) (England) Regulations (2023) is based only on measured pollutant concentrations from the Automatic Urban and Rural Network (AURN) and modelling is not included in the assessment.
4.1 Approach for Nitrogen Dioxide at the roadside
In compliance assessments for years up to and including 2020, the approach taken when assessing NO2 concentrations at roadside locations where both modelled and measured concentrations were available was to report all concentrations, but to always use the highest concentration to determine the compliance status, whether measured or modelled.
This was a conservative approach in which an exceedance was always reported if any of the data indicated one, but it did not consider the quality of the evidence available. The availability of a new source of evidence - measurements from the UUNN, which was established in 2020 - prompted a review of the approach for NO2.
A study led by Defra working closely with members of their independent Air Quality Expert Group (AQEG) compared the quality of modelled NO2 concentrations from the PCM model to measured concentrations from the UUNN and AURN. This concluded that the AURN provides the most accurate assessment of NO2 concentrations, followed by the UUNN, and then the PCM model.
The method for determining compliance with the annual mean limit value for NO2 was therefore adjusted to reflect this. As of 2021, all modelled and measured NO2 concentrations are still reported as part of the assessment, but the order of precedence, for any given major urban road, is as follows:
- If AURN measurements are available, these have been used to assess compliance in preference to values from the UUNN and/or the PCM model for the same major urban road.
- If UUNN measurements (but not AURN measurements) are available, the UUNN measurements have been used to assess compliance in preference to values from the PCM model for the same major urban road.
- If no AURN or UUNN measurements are available, concentrations from the PCM model have been used to assess compliance.
This order of precedence only applies to results for the same major urban road. Therefore, the NO2 compliance status of a given zone could in theory still be determined on the basis of modelling, if the highest concentration for that zone was a modelled value for a location without co-located monitoring.
No change has been made to the method for determining compliance for other pollutants. This means that the most appropriate evidence-based approach is taken for each pollutant.
4.2 Compliance summary
The results of the air quality assessment for 2024 are summarised in the tables below. The tables have been completed as follows:
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where all measurements were within the relevant limit values in 2024, the table shows this as ‘Compliant’
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where locations were identified as exceeding a limit value, target value or long-term objective, this is shown as ‘Exceedance’
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if the compliance or exceedance was determined by supplementary assessment only, this is indicated by ‘[sup]’, i.e. ‘Compliant [sup]’ or ‘Exceedance [sup]’.
There are no longer any zones where margins of tolerance apply.
Sulphur dioxide (SO2): in 2024, all zones and agglomerations within the UK complied with the limit values for 1-hour mean and 24-hour mean SO2 concentration, set for protection of human health. All non-agglomeration zones within the UK also complied with the critical levels for annual mean and winter mean SO2 concentration, set for protection of ecosystems (these are not applicable to built-up areas).
Carbon monoxide (CO), benzene and lead: all zones and agglomerations were compliant with the limit values for these three pollutants in 2024. The 2024 compliance assessment for CO has been based on objective estimation, as explained in Defra’s technical report on UK air quality assessment (Pugsley, K. L. et al., 2025). This is underpinned by NAEI emission trends, AURN measurement trends and historical modelling assessments.
Nitrogen dioxide (NO2): in 2024, not every zone was compliant with all the limit values. The results of the air quality assessment for nitrogen dioxide for each zone are summarised in Table 31.
All zones and agglomerations were compliant with the 1-hour limit value (200 µg m-3) in 2024, with none exceeding this limit value on more than the permitted 18 occasions. Prior to 2020, only a few zones (typically one or two) have exceeded this limit value; 2024 is the fifth consecutive year in which all zones have been compliant.
38 zones met the annual mean limit value for NO2 (40 µg m-3) in 2024. The five zones that exceeded this limit value were:
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West Midlands Urban Area
-
Greater Manchester Urban Area
-
Liverpool Urban Area
-
Bristol Urban Area
-
Coventry/Bedworth
The year 2020 saw a large reduction in the number of zones exceeding the annual mean limit value: just five zones exceeded in 2020 compared to 33 zones in 2019. This was attributed to the reduced road traffic flows brought about by the COVID-19 pandemic lockdown restrictions. In the following year, 2021, 10 zones exceeded this limit value. In 2022, nine zones exceeded this limit value, and in 2023 also, nine zones exceeded this limit value. In 2024 the number of zones exceeding this limit value reduced further, to five.
All non-agglomeration zones within the UK complied with the critical level for annual mean NOX concentration, set for protection of vegetation, as has been the case for many years.
As part of the 2017 UK plan for tackling roadside nitrogen dioxide concentrations (Defra, 2017), local authorities in England with exceedances of the annual mean nitrogen dioxide limit value have been required to develop local plans or studies to consider measures to achieve the statutory limit value within the shortest possible time.
These studies or plans may include local scale modelling and/or monitoring data, and in some cases the local data present different results to the national air quality assessment. This is partly due to local monitoring being sited differently to national monitoring in order to target local pollution hotspots. Where possible, Defra is working to develop and improve the national NO2 compliance assessment to better reflect local level NO2 concentrations. This included establishing the UUNN in 2020, to provide more local NO2 measurement data.
Table 31: Results of Air Quality Assessment for Nitrogen Dioxide in 2024
| Zone | NO2 Limit Value for heath (1hr mean) | NO2 Limit Value for health (annual mean) | NOX critical level for vegetation (annual mean) |
|---|---|---|---|
| Greater London Urban Area | Compliant | Compliant | Not applicable |
| West Midlands Urban Area | Compliant | Exceedance [sup] | Not applicable |
| Greater Manchester Urban Area | Compliant | Exceedance [sup] | Not applicable |
| West Yorkshire Urban Area | Compliant | Compliant | Not applicable |
| Tyneside | Compliant | Compliant | Not applicable |
| Liverpool Urban Area | Compliant | Exceedance [sup] | Not applicable |
| Sheffield Urban Area | Compliant | Compliant | Not applicable |
| Nottingham Urban Area | Compliant | Compliant | Not applicable |
| Bristol Urban Area | Compliant | Exceedance [sup] | Not applicable |
| Brighton/Worthing/Littlehampton | Compliant | Compliant | Not applicable |
| Leicester Urban Area | Compliant | Compliant | Not applicable |
| Portsmouth Urban Area | Compliant | Compliant | Not applicable |
| Teesside Urban Area | Compliant | Compliant | Not applicable |
| The Potteries | Compliant | Compliant | Not applicable |
| Bournemouth Urban Area | Compliant | Compliant | Not applicable |
| Reading/Wokingham Urban Area | Compliant | Compliant | Not applicable |
| Coventry/Bedworth | Compliant | Exceedance [sup] | Not applicable |
| Kingston upon Hull | Compliant | Compliant | Not applicable |
| Southampton Urban Area | Compliant | Compliant | Not applicable |
| Birkenhead Urban Area | Compliant | Compliant | Not applicable |
| Southend Urban Area | Compliant | Compliant | Not applicable |
| Blackpool Urban Area | Compliant | Compliant | Not applicable |
| Preston Urban Area | Compliant | Compliant | Not applicable |
| Glasgow Urban Area | Compliant | Compliant | Not applicable |
| Edinburgh Urban Area | Compliant | Compliant | Not applicable |
| Cardiff Urban Area | Compliant | Compliant | Not applicable |
| Swansea Urban Area | Compliant | Compliant | Not applicable |
| Belfast Urban Area | Compliant | Compliant | Not applicable |
| Eastern | Compliant | Compliant | Compliant |
| South West | Compliant | Compliant | Compliant |
| South East | Compliant | Compliant | Compliant |
| East Midlands | Compliant | Compliant | Compliant |
| North West & Merseyside | Compliant | Compliant | Compliant [sup] |
| Yorkshire and Humberside | Compliant | Compliant | Compliant |
| West Midlands | Compliant | Compliant | Compliant [sup] |
| North East | Compliant | Compliant | Compliant [sup] |
| Central Scotland | Compliant | Compliant | Compliant [sup] |
| North East Scotland | Compliant | Compliant | Compliant [sup] |
| Highland | Compliant | Compliant | Compliant [sup] |
| Scottish Borders | Compliant | Compliant | Compliant |
| South Wales | Compliant | Compliant | Compliant |
| North Wales | Compliant | Compliant | Compliant |
| Northern Ireland | Compliant | Compliant | Compliant [sup] |
The abbreviation [sup] indicates the compliance or exceedance was determined by supplementary assessment only.
Particulate Matter as PM10: all zones and agglomerations were compliant with the annual mean limit value of 40 µg m-3 for PM10. All zones and agglomerations were also compliant with the daily mean limit value of 50 µg m-3, which must not be exceeded more than 35 times a year.
The results of the air quality assessment for PM10 for each zone, with respect to the daily mean and annual mean limit values, are summarised in Table 32.
Table 32: Results of Air Quality Assessment for PM10 in 2024
| Zone | PM10 Limit Value (daily mean) | PM10 Limit Value (annual mean) |
|---|---|---|
| Greater London Urban Area | Compliant | Compliant |
| West Midlands Urban Area | Compliant | Compliant |
| Greater Manchester Urban Area | Compliant | Compliant |
| West Yorkshire Urban Area | Compliant | Compliant |
| Tyneside | Compliant | Compliant |
| Liverpool Urban Area | Compliant | Compliant |
| Sheffield Urban Area | Compliant | Compliant |
| Nottingham Urban Area | Compliant | Compliant |
| Bristol Urban Area | Compliant | Compliant |
| Brighton/Worthing/Littlehampton | Compliant [sup] | Compliant [sup] |
| Leicester Urban Area | Compliant | Compliant |
| Portsmouth Urban Area | Compliant | Compliant |
| Teesside Urban Area | Compliant | Compliant |
| The Potteries | Compliant | Compliant |
| Bournemouth Urban Area | Compliant [sup] | Compliant [sup] |
| Reading/Wokingham Urban Area | Compliant | Compliant |
| Coventry/Bedworth | Compliant | Compliant |
| Kingston upon Hull | Compliant | Compliant |
| Southampton Urban Area | Compliant | Compliant |
| Birkenhead Urban Area | Compliant | Compliant |
| Southend Urban Area | Compliant | Compliant |
| Blackpool Urban Area | Compliant | Compliant |
| Preston Urban Area | Compliant | Compliant |
| Glasgow Urban Area | Compliant | Compliant |
| Edinburgh Urban Area | Compliant | Compliant |
| Cardiff Urban Area | Compliant | Compliant |
| Swansea Urban Area | Compliant | Compliant |
| Belfast Metropolitan Urban Area | Compliant | Compliant |
| Eastern | Compliant | Compliant |
| South West | Compliant | Compliant |
| South East | Compliant | Compliant |
| East Midlands | Compliant | Compliant |
| North West and Merseyside | Compliant | Compliant |
| Yorkshire and Humberside | Compliant | Compliant |
| West Midlands | Compliant | Compliant |
| North East | Compliant | Compliant |
| Central Scotland | Compliant | Compliant |
| North East Scotland | Compliant | Compliant |
| Highland | Compliant | Compliant |
| Scottish Borders | Compliant [sup] | Compliant [sup] |
| South Wales | Compliant | Compliant |
| North Wales | Compliant | Compliant |
| Northern Ireland | Compliant | Compliant |
The abbreviation [sup] indicates the compliance or exceedance was determined by supplementary assessment only.
Particulate Matter as PM2.5: all zones met the annual mean limit value (20 µg m-3 to have been achieved by 1 Jan 2020).
The results of the air quality assessment for PM2.5 for each zone are summarised in Table 33. Subtraction of contributions due to natural sources is not permitted for PM2.5.
Under the AQSR (2010), the UK was required to achieve a National Exposure Reduction Target (NERT) for PM2.5, over the period 2010 to 2020. The UK achieved the NERT in 2016, well before the 2020 target year, but has continued to report compliance annually, even after 2020, to demonstrate that it remains compliant.
Compliance is assessed on the basis of the Average Exposure Indicator (AEI) statistic. The AEI for the UK is calculated as follows:
- each year, the annual arithmetic mean PM2.5 concentration is calculated for the designated AEI subset of urban background sites1
- the mean of the most recent three calendar years’ values is taken as the AEI.
The detailed methodology and results of this calculation are presented in Defra’s technical report on UK air quality assessment (Pugsley, K. L. et al., 2025).
The AEI for the reference year (2010) was 13 µg m-3; based on this, the AQSR set an exposure reduction target of 15%, which equated to reducing the AEI to 11 µg m-3 by 2020.
Most recent annual mean urban background PM2.5 concentrations (to one decimal place) were as follows:
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2022: 8.3 µg m-3
-
2023: 7.3 µg m-3
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2024: 7.2 µg m-3
The three-year running mean AEI for 2024 (calculated as the mean of the above annual values, rounded to the nearest integer), is 8 µg m-3. Therefore, the UK remained compliant with the NERT in 2024.
Table 33: Results of Air Quality Assessment for PM2.5 in 2024
| Zone | PM2.5 annual mean limit value |
|---|---|
| Greater London Urban Area | Compliant |
| West Midlands Urban Area | Compliant |
| Greater Manchester Urban Area | Compliant |
| West Yorkshire Urban Area | Compliant |
| Tyneside | Compliant |
| Liverpool Urban Area | Compliant |
| Sheffield Urban Area | Compliant |
| Nottingham Urban Area | Compliant |
| Bristol Urban Area | Compliant |
| Brighton/Worthing/Littlehampton | Compliant |
| Leicester Urban Area | Compliant |
| Portsmouth Urban Area | Compliant |
| Teesside Urban Area | Compliant |
| The Potteries | Compliant |
| Bournemouth Urban Area | Compliant |
| Reading/Wokingham Urban Area | Compliant |
| Coventry/Bedworth | Compliant |
| Kingston upon Hull | Compliant |
| Southampton Urban Area | Compliant |
| Birkenhead Urban Area | Compliant |
| Southend Urban Area | Compliant |
| Blackpool Urban Area | Compliant |
| Preston Urban Area | Compliant |
| Glasgow Urban Area | Compliant |
| Edinburgh Urban Area | Compliant |
| Cardiff Urban Area | Compliant |
| Swansea Urban Area | Compliant |
| Belfast Metropolitan Urban Area | Compliant |
| Eastern | Compliant |
| South West | Compliant |
| South East | Compliant |
| East Midlands | Compliant |
| North West and Merseyside | Compliant |
| Yorkshire and Humberside | Compliant |
| West Midlands | Compliant |
| North East | Compliant |
| Central Scotland | Compliant |
| North East Scotland | Compliant |
| Highland | Compliant |
| Scottish Borders | Compliant [sup] |
| South Wales | Compliant |
| North Wales | Compliant |
| Northern Ireland | Compliant |
The abbreviation [sup] indicates the compliance or exceedance was determined by supplementary assessment only.
Also, as explained in Section 1, the Environmental Targets (Fine Particulate Matter) (England) Regulations (2023) (UK Government, 2023) contain the following long-term targets for PM2.5:
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an Annual Mean Concentration Target (AMCT) - to reduce maximum annual mean (average) PM2.5 concentrations in England to 10 µg m-3 by 2040
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a Population Exposure Reduction Target (PERT), to reduce population exposure to PM2.5 in England by 35% compared to 2018, by 2040. The PERT is based on an average of measurements from urban background and suburban background monitoring sites.
Compliance with the targets is a legal requirement from 2040 onwards, but there are interim targets which are not legally mandatory. The targets apply only in England.
The AMCT will be considered met if, at every relevant monitoring station, the annual mean (average) concentration of PM2.5 in ambient air, rounded to the nearest whole number of µg m-3, is equal to or less than the target level in the year 2040.
One AURN site in England exceeded the AMCT of 10 µg m-3 in 2024. This was London Marylebone Road, a roadside site in central London. All AURN sites met the interim AMCT in 2024. This is a maximum of 12 µg m-3 to be achieved by January 2028.
Progress towards meeting the PERT is assessed using a ‘Population Exposure Indicator’ (PEIyear) - a measure of average population exposure in the three-year period ending on 31 December in a given year. The reduction in population exposure is found by comparing the PEIyear against the Baseline Population Exposure Indicator (‘PEIbase’) - the average for the three years 2016, 2017 and 2018. PEIbase is 10.09 µg m-3. A statistical method to account for changes in the monitoring network is used in the calculation of the percentage reduction, so the comparison is not direct.
PEI2024 is 7.56 µg m-3. The reduction in population exposure from 2018 to 2024 is 25%: England therefore met the interim PERT of 22% in 2024, though not the long-term target of 35% to be met by December 2040.
How England has progressed towards achieving the AMCT and PERT since 2018 is reported in Section 5.
Ozone: in 2024 all zones of the UK met the target values for health and for protection of vegetation, as they have for many years. However, some zones exceeded the more stringent long-term objectives.
For ozone (O3), the target value for protection of human health is based on the maximum daily 8-hour mean. All 43 zones and agglomerations were compliant with this target value, which is assessed as an average over a three-year period. There is also a more stringent long-term objective for protection of human health, also based on the maximum daily 8-hour mean, assessed over a single year. Twelve of the 43 zones and agglomerations were compliant with the long-term objective (LTO) for health in 2024. The results of the air quality assessment for ozone, in relation to the target value and LTO for human health, are summarised in Table 34.
The target value for protection of vegetation is based on the AOT40 statistic. This statistic (expressed in µg m-3.hours) is the sum of the difference between hourly concentrations greater than 80 µg m-3 (= 40 ppb) over a given period using only the hourly mean values measured between 08:00 and 20:00 Central European Time each day from 1 May to 31 July each year as an average over a five-year period. All 43 zones and agglomerations met the target value based on the AOT40 statistic.
There is also a more stringent long-term objective for protection of vegetation, also based on the AOT40 statistic assessed over a single year; 4 zones exceeded this long-term objective for vegetation in 2024. The results of the air quality assessment for ozone, in relation to the target value and LTO for vegetation, are summarised in Table 35.
Ozone concentrations, and hence the number of zones exceeding the LTOs, fluctuate from year to year as ozone is a transboundary pollutant (travelling long distances across countries) and its formation is influenced by meteorological factors. Ozone is not emitted from sources in the same way as most other air pollutants. It is the product of chemical reactions between other pollutants in the air, both human-made and from natural sources, that occur more frequently during hot and sunny weather. In 2024 there were relatively few periods of elevated ozone concentration, and fewer exceedances of the LTO for vegetation in 2024 than in 2023.
In 2024 there were no exceedances of the population warning threshold of 240 µg m-3 as a 1-hour mean. This is not unusual. However, there were also no measured exceedances of the (lower) ozone population information threshold of 180 µg m-3 (also as a 1-hour mean). This is relatively rare, although the number varies from year to year. For comparison, there were 26 exceedances of the population information threshold reported in the previous year, 2023.
Table 34: Results of Air Quality Assessment for Ozone in 2024: 8-hour Mean Target Value and Long-Term Objective for Human Health
| Zone | O3 8h Mean Target Value for human health | O3 8h Mean Long-Term Objective for human health |
|---|---|---|
| Greater London Urban Area | Compliant | Exceedance |
| West Midlands Urban Area | Compliant | Exceedance |
| Greater Manchester Urban Area | Compliant [sup] | Exceedance [sup] |
| West Yorkshire Urban Area | Compliant [sup] | Exceedance [sup] |
| Tyneside | Compliant | Compliant |
| Liverpool Urban Area | Compliant [sup] | Exceedance [sup] |
| Sheffield Urban Area | Compliant [sup] | Exceedance [sup] |
| Nottingham Urban Area | Compliant | Exceedance |
| Bristol Urban Area | Compliant | Exceedance |
| Brighton/Worthing/Littlehampton | Compliant | Exceedance |
| Leicester Urban Area | Compliant | Exceedance |
| Portsmouth Urban Area | Compliant | Exceedance |
| Teesside Urban Area | Compliant | Compliant |
| The Potteries | Compliant | Exceedance |
| Bournemouth Urban Area | Compliant | Exceedance |
| Reading/Wokingham Urban Area | Compliant | Exceedance |
| Coventry/Bedworth | Compliant | Exceedance |
| Kingston upon Hull | Compliant | Compliant |
| Southampton Urban Area | Compliant | Exceedance |
| Birkenhead Urban Area | Compliant [sup] | Exceedance [sup] |
| Southend Urban Area | Compliant | Exceedance |
| Blackpool Urban Area | Compliant [sup] | Exceedance [sup] |
| Preston Urban Area | Compliant [sup] | Exceedance [sup] |
| Glasgow Urban Area | Compliant | Compliant |
| Edinburgh Urban Area | Compliant | Compliant |
| Cardiff Urban Area | Compliant | Exceedance |
| Swansea Urban Area | Compliant [sup] | Exceedance [sup] |
| Belfast Metropolitan Urban Area | Compliant | Compliant |
| Eastern | Compliant | Exceedance |
| South West | Compliant | Exceedance |
| South East | Compliant | Exceedance |
| East Midlands | Compliant | Exceedance |
| North West and Merseyside | Compliant | Exceedance |
| Yorkshire and Humberside | Compliant [sup] | Exceedance [sup] |
| West Midlands | Compliant | Exceedance |
| North East | Compliant | Compliant |
| Central Scotland | Compliant | Compliant |
| North East Scotland | Compliant | Compliant |
| Highland | Compliant | Compliant |
| Scottish Borders | Compliant | Compliant |
| South Wales | Compliant [sup] | Exceedance [sup] |
| North Wales | Compliant | Exceedance |
| Northern Ireland | Compliant | Compliant |
The abbreviation ‘[sup]’ indicates the compliance or exceedance was determined by supplementary assessment only.
Table 35: Results of Air Quality Assessment for Ozone in 2024: Target Value and Long-Term Objective Based On AOT40 Statistic, for Vegetation
| Zone | O3 Target Value for vegetation (AOT40) | O3 Long-Term Objective for vegetation (AOT40) |
|---|---|---|
| Greater London Urban Area | Compliant | Exceedance |
| West Midlands Urban Area | Compliant | Compliant |
| Greater Manchester Urban Area | Compliant [sup] | Compliant |
| West Yorkshire Urban Area | Compliant [sup] | Compliant |
| Tyneside | Compliant | Compliant |
| Liverpool Urban Area | Compliant [sup] | Compliant |
| Sheffield Urban Area | Compliant [sup] | Compliant |
| Nottingham Urban Area | Compliant | Compliant |
| Bristol Urban Area | Compliant | Compliant |
| Brighton/Worthing/Littlehampton | Compliant | Compliant |
| Leicester Urban Area | Compliant | Compliant |
| Portsmouth Urban Area | Compliant | Compliant |
| Teesside Urban Area | Compliant | Compliant |
| The Potteries | Compliant | Compliant |
| Bournemouth Urban Area | Compliant | Exceedance |
| Reading/Wokingham Urban Area | Compliant | Compliant |
| Coventry/Bedworth | Compliant | Compliant |
| Kingston upon Hull | Compliant | Compliant |
| Southampton Urban Area | Compliant | Compliant |
| Birkenhead Urban Area | Compliant [sup] | Compliant |
| Southend Urban Area | Compliant | Compliant |
| Blackpool Urban Area | Compliant [sup] | Compliant |
| Preston Urban Area | Compliant [sup] | Compliant |
| Glasgow Urban Area | Compliant | Compliant |
| Edinburgh Urban Area | Compliant | Compliant [sup] |
| Cardiff Urban Area | Compliant | Compliant |
| Swansea Urban Area | Compliant [sup] | Compliant |
| Belfast Metropolitan Urban Area | Compliant | Compliant |
| Eastern | Compliant | Compliant |
| South West | Compliant | Exceedance |
| South East | Compliant | Exceedance |
| East Midlands | Compliant | Compliant |
| North West and Merseyside | Compliant | Compliant |
| Yorkshire and Humberside | Compliant [sup] | Compliant |
| West Midlands | Compliant | Compliant |
| North East | Compliant | Compliant |
| Central Scotland | Compliant | Compliant |
| North East Scotland | Compliant | Compliant |
| Highland | Compliant | Compliant |
| Scottish Borders | Compliant | Compliant |
| South Wales | Compliant [sup] | Compliant |
| North Wales | Compliant | Compliant |
| Northern Ireland | Compliant | Compliant |
The abbreviation ‘[sup]’ indicates that the compliance or exceedance was determined by supplementary assessment only.
Arsenic, cadmium, nickel and benzo[a]pyrene: the air quality assessments for arsenic (As), cadmium (Cd), nickel (Ni) and benzo[a]pyrene (B[a]P) are summarised in Table 36. All zones met target values for arsenic and cadmium (as they have for many years). For the first time, all zones also met the target value for benzo[a]pyrene.
Concentrations of Ni exceeded the target value of 20 ng m-3 in three zones: Sheffield Urban Area, Yorkshire and Humberside, and South Wales. These exceedances are attributed to emissions from industrial sources.
Table 36: Results of Air Quality Assessment for As, Cd, Ni and B[a]P in 2024
| Zone | As Target Value | Cd Target Value | Ni Target Value | B[a]P Target Value |
|---|---|---|---|---|
| Greater London Urban Area | Compliant | Compliant | Compliant | Compliant |
| West Midlands Urban Area | Compliant | Compliant | Compliant | Compliant |
| Greater Manchester Urban Area | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant |
| West Yorkshire Urban Area | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant |
| Tyneside | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant |
| Liverpool Urban Area | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant |
| Sheffield Urban Area | Compliant | Compliant | Exceedance [sup] | Compliant |
| Nottingham Urban Area | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant |
| Bristol Urban Area | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant |
| Brighton/Worthing/Littlehampton | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant [sup] |
| Leicester Urban Area | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant [sup] |
| Portsmouth Urban Area | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant |
| Teesside Urban Area | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant |
| The Potteries | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant [sup] |
| Bournemouth Urban Area | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant [sup] |
| Reading/Wokingham Urban Area | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant [sup] |
| Coventry/Bedworth | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant [sup] |
| Kingston upon Hull | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant [sup] |
| Southampton Urban Area | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant |
| Birkenhead Urban Area | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant [sup] |
| Southend Urban Area | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant [sup] |
| Blackpool Urban Area | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant [sup] |
| Preston Urban Area | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant |
| Glasgow Urban Area | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant |
| Edinburgh Urban Area | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant |
| Cardiff Urban Area | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant |
| Swansea Urban Area | Compliant | Compliant | Compliant | Compliant |
| Belfast Urban Area | Compliant | Compliant | Compliant | Compliant |
| Eastern | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant |
| South West | Compliant | Compliant | Compliant | Compliant |
| South East | Compliant | Compliant | Compliant | Compliant |
| East Midlands | Compliant | Compliant | Compliant | Compliant |
| North West and Merseyside | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant |
| Yorkshire and Humberside | Compliant | Compliant | Exceedance [sup] | Compliant |
| West Midlands | Compliant | Compliant | Compliant | Compliant [sup] |
| North East | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant [sup] |
| Central Scotland | Compliant | Compliant | Compliant | Compliant |
| North East Scotland | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant [sup] |
| Highland | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant |
| Scottish Borders | Compliant | Compliant | Compliant | Compliant [sup] |
| South Wales | Compliant | Compliant | Exceedance [sup] | Compliant |
| North Wales | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant [sup] |
| Northern Ireland | Compliant [sup] | Compliant [sup] | Compliant [sup] | Compliant |
‘[sup]’ indicates the compliance or exceedance was determined by supplementary assessment only.
5. Comparison with previous years
This section provides information on non-compliances in previous years from 2008 onwards. 2008 is the year that the Air Quality Directive came into force - which was subsequently transposed into UK legislation by The Air Quality Standards Regulations (AQSR) (2010).
For SO2, Pb, benzene and CO, the UK has been compliant with all limit values set in the AQSR since 2008. For PM2.5, the UK has been compliant with the AQSR limit value (20 µg m-3 to have been achieved by 1 Jan 2020) since 2015. For information on compliance with the 1st and 2nd Daughter Directives for all pollutants in earlier years, see the 2012 or earlier reports in this series.
The UK has been compliant with the limit values for both Pb and CO since 2003, and for benzene since 2007: these limit values are the same as those contained in the 1st and 2nd Daughter Directives, which the Air Quality Directive and the AQSR (2010) superseded.
For nitrogen dioxide, Table 41 summarises the results of the air quality assessment in years from 2008 to 2024. This table shows the numbers of zones exceeding the limit value in each year. In years up to 2014 inclusive, some zones were granted a time extension.
In these cases, the zone was deemed compliant so long as the limit value plus an agreed margin of tolerance (MOT) was not exceeded. The right-hand column of this table lists the number of zones which exceeded the limit value but were compliant within the provisions of the agreed time extension and MOT. The last time extension ended on 1 January 2015.
All non-agglomeration zones within the UK have complied with the critical level for annual mean NOX concentration, set for protection of vegetation, in years 2008 onwards.
For PM10, Table 42 summarises the results of the air quality assessment in years from 2008 to 2024. Time extensions were in place up to the end of 2011 for some zones.
For PM2.5, Table 43 shows no zones in exceedance of the AQSR annual mean limit value (20 µg m-3).
Table 41: Non-Compliances with Limit Values for Nitrogen Dioxide, 2008 to 2024
| Year | Zones Exceeding NO2 LV for health (1hr mean) | Zones Exceeding NO2 LV for health (annual mean) | Additional zones which exceeded the annual mean LV but were covered by time extensions and were within the LV + MOT therefore compliant |
|---|---|---|---|
| 2008 | 3 zones (London, Glasgow, N.E. Scotland) | 40 zones | Not applicable |
| 2009 | 2 zones (London, Glasgow) | 40 zones | Not applicable |
| 2010 | 3 zones (London, Teesside, Glasgow) | 40 zones | Not applicable |
| 2011 | 3 zones (London, Glasgow, South East) | 35 zones | 5 zones |
| 2012 | 2 zones (London, South East) | 34 zones | 4 zones |
| 2013 | 1 zone (London) | 31 zones | 7 zones |
| 2014 | 2 zones (London, South Wales) | 30 zones | 8 zones |
| 2015 | 2 zones (London, South Wales) | 37 zones | 2015 was the first year with no time extensions for NO2: hence the apparent increase in zones exceeding in 2015. |
| 2016 | 2 zones (London, South Wales) | 37 zones | All time extensions ended. |
| 2017 | 2 zones (London, South Wales) | 37 zones | All time extensions ended. |
| 2018 | 2 zones (London, South Wales) | 36 zones | All time extensions ended. |
| 2019 | 1 zone (South Wales) | 33 zones | All time extensions ended. |
| 2020 | None | 5 zones | All time extensions ended. |
| 2021 | None | 10 zones | All time extensions ended. |
| 2022 | None | 9 zones | All time extensions ended. |
| 2023 | None | 9 zones | All time extensions ended. |
| 2024 | None | 5 zones | All time extensions ended. |
Table 42: Non-Compliances with the Limit Values for PM10, 2008 to 2024
| Year | PM10 LV (annual mean) | PM10 LV (daily mean) | Additional Zones with Time Extensions, Compliant with AM LV + MOT after Subtraction of Natural Contribution |
|---|---|---|---|
| 2008 | None | 2 zones (1 zone after subtraction of natural contribution) | Not applicable |
| 2009 | None | 3 zones (1 zone after subtraction of natural contribution) | Not applicable |
| 2010 | None | None (after subtraction of natural contribution) | 1 zone |
| 2011 | None | None (after subtraction of natural contribution) | 1 zone |
| 2012 | None | None (after subtraction of natural contribution) | All time extensions ended. |
| 2013 | None | None (after subtraction of natural contribution) | All time extensions ended. |
| 2014 | None | None (after subtraction of natural contribution) | All time extensions ended. |
| 2015 | None | None (after subtraction of natural contribution) | All time extensions ended. |
| 2016 | None | None | All time extensions ended. |
| 2017 | None | None | All time extensions ended. |
| 2018 | None | None | All time extensions ended. |
| 2019 | None | None | All time extensions ended. |
| 2020 | None | None | All time extensions ended. |
| 2021 | None | None | All time extensions ended. |
| 2022 | None | None | All time extensions ended. |
| 2023 | None | None | All time extensions ended. |
| 2024 | None | None | All time extensions ended. |
Table 43: Non-Compliances with the PM2.5 Annual Mean Limit Value 2008 to 2024
| Year | PM2.5 Annual Mean Limit Value (20 µg m-3) – number of zones |
|---|---|
| 2008 | None |
| 2009 | None |
| 2010 | None |
| 2011 | None |
| 2012 | None |
| 2013 | None |
| 2014 | None |
| 2015 | None |
| 2016 | None |
| 2017 | None |
| 2018 | None |
| 2019 | None |
| 2020 | None |
| 2021 | None |
| 2022 | None |
| 2023 | None |
| 2024 | None |
Figure 41 shows how measured concentrations of PM2.5 are changing over time and compares them to the long-term (2040 target) and interim (2028 target) Annual Mean Concentration Target (AMCT).
This figure illustrates the gradual decrease in measured concentrations, from the situation in 2010 when the majority of sites had annual mean concentrations above the interim 2028 target, to 2024 when all sites were within the interim 2028 target and most also met the target for 2040. One AURN site in England exceeded the 2040 target of 10 µg m-3 in 2024. This was London Marylebone Road, a roadside site in central London. All AURN sites met the interim 2028 target in 2024.
Figure 41: AMCT for PM2.5: progress from 2009 to 2024 (sites by status, per cent of total sites).
Figure 42 illustrates progress towards meeting the PERT (i.e. the 2040 target of a 35 per cent reduction compared to 2018) and the interim target (i.e. the 2028 target of a 22 per cent reduction compared to 2018): the bars indicate the percentage decrease in population exposure since 2018. This illustrates that in 2024, population exposure to PM2.5 across England had reduced by 25 per cent since 2018.
Figure 42: PERT for PM2.5: progress, per cent reduction in population exposure to PM2.5 from 2018 to 2024.
Information on progress towards meeting the PM2.5 targets is available on the UK-AIR website’s progress page and the methodology for the PERT and AMCT can be found on the UK-AIR website’s calculation page.
For ozone, Table 44 summarises annual exceedances of the target value for human health (based on the maximum daily 8-hour mean), the target value for protection of vegetation (based on the AOT40 statistic), and the two long-term objectives (LTOs) based on these two metrics.
For the pollutants formerly covered by the Fourth Daughter Directive, the UK has been compliant with the target values for As and Cd since 2008 or earlier. Table 45 summarises the numbers of zones with exceedances of target values for Ni and benzo[a]pyrene (B[a]P) in previous years.
Table 44: Exceedances of Target Values for Ozone (Health) and Long-Term Objectives, 2008 to 2024
| Year | 8-Hour Mean Target Value | AOT40 Target Value | 8-Hour Mean LTO | AOT40 LTO |
|---|---|---|---|---|
| 2008 | 1 zone measured (Eastern) | None | 43 zones | 41 zones |
| 2009 | None | None | 39 zones | 10 zones |
| 2010 | None | None | 41 zones | 6 zones |
| 2011 | None | None | 43 zones | 3 zones |
| 2012 | None | None | 41 zones | 3 zones |
| 2013 | None | None | 33 zones | 8 zones |
| 2014 | None | None | 32 zones | 3 zones |
| 2015 | None | None | 43 zones | 1 zone |
| 2016 | None | None | 42 zones | 5 zones |
| 2017 | None | None | 34 zones | None |
| 2018 | None | None | 43 zones | 38 zones |
| 2019 | None | None | 43 zones | 6 zones |
| 2020 | None | None | 40 zones | 16 zones |
| 2021 | None | None | 39 zones | 1 zone |
| 2022 | None | None | 43 zones | 11 zones |
| 2023 | None | None | 42 zones | 30 zones |
| 2024 | None | None | 31 zones | 4 zones |
Table 45: Zones Exceeding Target Values for Ni and B[a]P, 2008 to 2024
| Year | Ni | B[a]P |
|---|---|---|
| 2008 | 2 (Swansea, South Wales) | 6 (Yorks and Humberside, Teesside, Northern Ireland, Swansea, South Wales, Belfast) |
| 2009 | 2 (Swansea, South Wales) | 6 (Yorks and Humberside, Northern Ireland, Teesside, Swansea, North East, South Wales) |
| 2010 | 2 (Swansea, South Wales) | 8 (Yorks and Humber, N. Ireland, Teesside, Belfast, W Midlands, North East, South Wales, North Wales.) |
| 2011 | 2 (Swansea, South Wales) | 7 (Yorks and Humberside, N. Ireland, Teesside, Swansea, Belfast, North East, South Wales) |
| 2012 | 2 (Swansea, South Wales) | 8 (Yorks and Humberside, Teesside, Swansea, Belfast, North East, South Wales, North Wales, N. Ireland.) |
| 2013 | 2 (Swansea, South Wales) | 6 (Yorks and Humberside, Teesside, Swansea, East Midlands, North East, South Wales.) |
| 2014 | 3 (Sheffield, Swansea, South Wales) | 6 (Yorks and Humberside, Teesside, Swansea, East Midlands, North East, and South Wales). |
| 2015 | 2 (Swansea, South Wales) | 5 (Yorks and Humberside, Teesside, Swansea, North East and South Wales). |
| 2016 | 3 (Sheffield, Swansea, South Wales) | 4 (Yorks and Humberside, Swansea, South Wales and Northern Ireland). |
| 2017 | None | 3 (Yorks and Humberside, Swansea, South Wales) |
| 2018 | 4 (Sheffield, Yorks and Humber., Swansea, South Wales) | 3 (Yorks and Humberside, Swansea, South Wales) |
| 2019 | 4 (Sheffield, Yorks and Humber., Swansea, South Wales) | 3 (Yorks and Humberside, Swansea, South Wales) |
| 2020 | 4 (Sheffield, Yorks and Humber., Swansea, South Wales) | 3 (Yorks and Humberside, Swansea, South Wales) |
| 2021 | 4 (Sheffield, Yorks and Humber., Swansea, South Wales) | 2 (Swansea and South Wales) |
| 2022 | 3 (Sheffield, Yorks and Humberside, South Wales) | 2 (Swansea and South Wales) |
| 2023 | 3 (Sheffield, Yorks and Humberside, South Wales) | 2 (Swansea and South Wales) |
| 2024 | 3 (Sheffield, Yorks and Humberside, South Wales) | None |
6. Where to find out more
Defra has published a Guide to Air Pollution Information Resources, detailing the types of information that are made available.
Information on the UK’s air quality, now and in the past, is available on UK-AIR, the Defra online air quality resource, and the national repository for historic air quality data. Tools available on UK-AIR include the UK Ambient Air Quality Interactive Map that allows you to look at outputs for the national modelling conducted for this compliance assessment, based on pollutant, background or roadside and geographical location.
UK-AIR also provides a daily air quality forecast, which is further disseminated via email, RSS feeds and X (formerly Twitter).
Latest forecasts are issued daily, at the UK-AIR website’s forecasting page.
Defra also provides a free telephone information service, with current air pollution levels and forecasts updated every hour.
To use this service, call 0800 556677 and follow the instructions.
Similar national online air quality resources have also been developed for Scotland, Wales and Northern Ireland:
Together, these 4 national websites provide a comprehensive resource for data and analyses covering all aspects of air quality throughout the UK and all its regions.
The Devolved Administrations each produce their own short annual report, providing more specific information on air quality in their parts of the UK. These reports are available from the above websites. Additional information from the Devolved Administrations of Scotland, Wales and Northern Ireland can be found at:
-
The Welsh Government Environment and Climate Change web page
-
The Northern Ireland Department of Agriculture, Environment and Rural Affairs (DAERA) web page
Detailed pollutant emission data for the UK are available from the National Atmospheric Emissions Inventory (NAEI).
The Clean Air Hub brings together information on air pollution, how it affects our health, and the actions we can take both to protect ourselves from it, and to help tackle it. There is also information on the annual Clean Air Day. The Clean Air Hub is coordinated by the Global Action Plan.
7. References
DAERA, 2017. The Air Quality Standards (Amendment) Regulations (Northern Ireland) 2017 [Accessed 30 July 2025].
Defra, 2017. UK plan for tackling roadside nitrogen dioxide concentrations [Accessed 31 July 2025].
Department of Environment Northern Ireland, 2010. The Air Quality Standards Regulations (Northern Ireland) 2010 [Accessed 30 July 2025].
European Parliament and Council of the European Union, 2008. Council Directive on ambient air quality and cleaner air for Europe (2008/50/EC) [Accessed 30 July 2025].
HM Government of Gibraltar, 2016. Environment (Air Quality Standards) (Amendment) Regulations 2016 (Legal Notice No. 2016/242) [Accessed 30 July 2025].
Pugsley, K. L. et al., 2025. Technical report on UK supplementary modelling assessment under the Air Quality Standards Regulations 2010 for 2023 [Accessed 30 July 2025].
Scottish Government, 2010. The Air Quality Standards (Scotland) Regulations [Accessed 30 July 2025].
Scottish Government, 2016. The Air Quality Standards (Scotland) Amendment Regulations 2016 [Accessed 30 July 2025].
UK Government, 2010. UK Air Quality Standards Regulations 2010 [Accessed 30 July 2025].
UK Government, 2016. The Air Quality Standards (Amendment) Regulations 2016 [Accessed 30 July 2025].
UK Government, 2023. The Environmental Targets (Fine Particulate Matter) (England) Regulations 2023 [Accessed 30 July 2025].
Welsh Government, 2010. The Air Quality Standards (Wales) Regulations [Accessed 30 July 2025].