Research and analysis

Nickel compliance assessment 2025

Published 9 October 2026

This compliance assessment is part of Air pollution in the UK 2025. There is a page for each of 12 pollutants.

This page provides the UK’s compliance assessment for 2025 against the nickel target value set for the protection of health.

The compliance criteria is set in the Air Quality Standards Regulations (2010).

The Air Quality Standards Regulations (2010) require reporting of compliance on an annual basis. This report continues the series of annual compliance reporting.

1. Nickel pollution and its impacts

Nickel (Ni) is a metallic element found in ambient air as a result of releases from oil and coal combustion, metal processes, manufacturing and other sources such as cigarette smoke.

A small number of UK zones have historically exceeded applicable target values for annual mean concentrations of nickel in ambient air, due to local industrial emissions. There are annual plans published which report the actions and measures already taken or planned, to help the UK meet the target values in the future.

Nickel and its compounds are toxic by inhalation, ingestion and skin contact. Long-term inhalation exposure to nickel compounds can cause adverse respiratory effects, including irritation and inflammation, and increase the risk of lung and nasal cancers as reported by the UK Health Security Agency.

In the environment, nickel can pollute soil and water, leading to exposure via these routes.

2. Sources of nickel pollution

The release of pollutants into the atmosphere is known as emissions. Annual UK emissions of nickel are estimated each year in the National Atmospheric Emissions Inventory (NAEI). The NAEI provides estimates of the total amount emitted during a calendar year. The latest estimates currently available are for 2024.

The NAEI reports emissions of nickel from human activities in the UK, but there are a few exceptions included as memo items, such as international shipping and aviation. The information presented here does not include memo items.

Figure 1 shows the split of nickel emissions in 2024 between various sources. Domestic combustion, specifically the burning of petroleum coke and solid fuels containing petroleum coke, was the largest single contributor of nickel emissions in 2024.

Figure 1: UK annual emissions of nickel by 2024 major emission source: 1990, 2005, 2023 and 2024

Notes:

1. ‘Domestic combustion’ refers to households burning a variety of fuels, for example in stoves and fireplaces.
2. ‘Industrial processes and product use’ refers to specific industrial production processes, including some where fuel combustion is a necessary part of the process, such as the production of steel. ‘Industrial combustion’ refers to the burning of fuels on manufacturing and construction sites, to generate energy for industrial use, for example to drive mobile machinery or to create heat or electricity for industrial processes.
3. Sources are ordered by emissions in 2024 from highest to lowest, excluding ‘Other’.
4. Further detail on emission source categories is available in the latest Methods for NAEI emissions data document.

3. Trends in nickel pollution

How nickel concentrations have changed over time since 2004 is shown in Figure 2. While there have been some fluctuations, average measured nickel concentrations have remained relatively stable in the last 20 years.

The average concentration has been calculated from all stations in the Heavy Metals Monitoring Network that had an annual data capture greater than or equal to 75 per cent. The shaded areas represent the 90 per cent confidence interval.

Trends over time can be influenced by changes to the number of monitoring sites and their locations. The pattern shown here will therefore exhibit some effect of changes to the structure of the monitoring network over time.

Figure 2: Annual mean concentrations of nickel in the UK, 2004 to 2025

4. Spatial variation of nickel pollution

Figure 3 shows modelled annual mean nickel concentrations for 2025 for each 1x1km grid square of the UK. The data comes from the CMAQ-Urban Model used for supplementary assessment against the target value set for nickel, as set out in Section 6 and 7. The majority of the UK experiences nickel concentrations less than 5 ng/m3. However, there are localised areas of elevated concentrations around Sheffield and Swansea, due to known industrial activities.

Historically there have been long-term exceedances in the Swansea valley within the South Wales non-agglomeration zone and in the Tinsley area of Sheffield which is close to zone boundaries and so spans the Yorkshire & Humberside non-agglomeration zone and the Sheffield Urban Area agglomeration zone. Reports on measures taken to address these exceedances have previously been published. 

Figure 3: Modelled annual mean nickel concentrations for 2025

5. Nickel target value

This section outlines the target value set for nickel concentrations.

Compliance against the nickel target value is assessed within each zone of the UK; for further information on the definition of agglomeration and non-agglomeration zones see the methods for 2025 Air Quality Standards Regulations (2010) compliance assessment.

Table 1: Nickel compliance criteria

Description	Averaging period	Metric
Nickel target value for health	Annual mean	20 ng/m3

Note 1: target value relates to the total content of nickel in the PM10 fraction.

The rules for assessing compliance are set out in the Air Quality Standards Regulations (2010), as amended.

6. Evidence used for assessing compliance

See the methods for 2025 Air Quality Standards Regulations (2010) compliance assessment

The evidence base for the annual assessment of compliance against the Air Quality Standards Regulations (2010) is underpinned by a combination of measurements and the results of modelling assessments.

The use of models enables air quality to be assessed at locations without monitoring sites. It has the added benefit of providing additional information on source apportionment and projections to support the development and implementation of air quality policies.

For further information on the measurements and the models used in the 2025 compliance assessment, and to download the data, see the air quality compliance assessment 2025: results and data tables. 

Monitoring

In 2025, there were 19 monitoring stations from Heavy Metals Network which met the data quality requirements for assessment against the nickel target value. This includes:

• 12 background stations
• one roadside monitoring station
• 5 industrial monitoring stations
• 6 rural background monitoring stations

Some nickel monitors are strategically placed around industrial locations to capture exceedances and help to evaluate modelling .

Modelling

The CMAQ-Urban Model was used for compliance assessment in 2025.

For assessment against the target value for nickel, 2 model outputs were calculated:

• annual mean nickel concentrations for each 1x1km grid square of the UK
• detailed modelling was conducted at a finer spatial scale around industrial locations known to cause exceedances of nickel – this provides additional evidence on whether concentrations are high in the areas that the public may be exposed

For more information on the modelling methods and for access to the data, please see the air quality compliance assessment 2025: modelled data and reports.

Modelled data is also made available in accessible formats within the air quality compliance assessment 2025: results and data tables.  

7. Compliance assessment for 2025

Not every zone was compliant with the annual mean nickel target value in 2025. 40 zones met the target value for Ni, but the 3 zones that exceeded this target value were:                                                                                                 

• Sheffield Urban Area
• Yorkshire & Humberside
• South Wales

The exceedances in the 2 zones in England are associated with the same industrial sources, since the industrial sources are close to the boundary between the 2 zones. These sources are a mixture of industrial point sources (a source at a known location) and fugitive sources (leaks or other releases) from a wide range of metal processing operations.

The exceedance in South Wales is generally attributed to emissions from a metal processing site.

The results of the assessment are also made available within the air quality compliance assessment 2025: results and data tables.

8. Changes in compliance over time

This section provides information on non-compliances in previous years from 2008 onwards. The target value for nickel was set in 2004 under the 4th Air Quality Daughter Directive, which was subsequently transposed into UK legislation by the Air Quality Standards Regulations (2010).

Figure 4 summarises the numbers of zones with exceedances of the target value for nickel in previous years. In 2017 there were no zones that exceeded the target value for nickel, but in all other years there have been between 2 and 4 zones in exceedances.

Since 2008, the exceedances have been limited to the following 4 zones:

• Sheffield Urban Area
• Yorkshire & Humberside
• Swansea Urban Area
• South Wales

In 2025, exceedances continue to be recorded in:

• Sheffield Urban Area
• Yorkshire & Humberside
• South Wales

The Air Quality Standards Regulations (2010) require the UK to report on measures in place to address exceedances of the annual mean nickel target value. The latest reports on measures provide detail on the assessment of these exceedances and report the action and measures that have already been taken or are planned to help the UK meet the target value.

Figure 4: Number of zones not compliant with nickel target value (2008 to 2025)