Benzene compliance assessment 2025
Published 9 October 2026
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This publication is available at https://www.gov.uk/government/publications/air-pollution-in-the-uk-2025/benzene-compliance-assessment-2025
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 benzene limit 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. Benzene pollution and its impacts
Benzene (C6H6) is an organic chemical compound. It is a hydrocarbon (that is, composed of carbon and hydrogen) and is a natural component of fossil fuels like crude oil and coal. Ambient benzene arises from domestic and industrial combustion processes, in addition to road transport. Tobacco smoking is a significant source of exposure to benzene in smokers.
Benzene is known to cause leukaemia and potentially other cancers in humans. No safe level can be specified for benzene in ambient air; however, the risk increases with increased exposure.
In the environment, benzene can pollute soil and water, leading to exposure via these routes.
2. Sources of benzene pollution
The release of pollutants into the atmosphere is known as emissions. Annual UK emissions of benzene 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 benzene 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 benzene emissions in 2024 between various sources. Domestic combustion was the largest single contributor of benzene emissions in 2024. Total UK emissions of benzene have reduced from between 1990 and 2024.
Figure 1: UK annual emissions of benzene by 2024 major emission source: 1990, 2005, 2023 and 2024
Notes:
- ‘Domestic combustion’ refers to households burning a variety of fuels, for example in stoves and fireplaces.
- ‘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.
- Sources are ordered by emissions in 2024 from highest to lowest, excluding ‘Other’.
- Further detail on emission source categories is available in the latest Methods for NAEI emissions data document.
3. Trends in benzene pollution
How benzene concentrations have changed over time since 1993 is shown in Figure 2. Average measured benzene concentrations have decreased from an annual mean of 6.0 µg/m3 in 1993, to 0.5 µg/m3 in 2025.
The average concentration has been calculated from all stations in the Hydrocarbons 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. The intervals narrow over time because of an increase in the number of monitoring stations and a reduction in the variation between annual means at monitoring stations.
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.
Significant drivers of the reduction in benzene concentrations have been the introduction of catalytic converters on car exhausts in the 1990s, and reductions in the maximum benzene content of petrol from 5 per cent to 1 per cent in 2000.
Figure 2: Annual mean concentrations of benzene in the UK, 1993 to 2025
4. Spatial variation
Figure 3 shows modelled annual mean benzene concentrations in 2025 for each 1x1km grid square of the UK. The vast majority of the UK experiences benzene concentrations below 1 µg/m3, with higher concentrations limited to an industrial area in Yorkshire & Humberside. The data comes from the CMAQ-Urban Model used for supplementary assessment against the benzene limit value set for the protection of health, as set out in section 6.
Figure 3: Modelled annual mean benzene concentrations for 2025
Note that Figure 3 shows the modelled annual average background concentration of benzene in each 1x1km grid square of the UK. Within the grid squares, there may be local areas of higher concentration close to specific emission sources.
5. Benzene limit value
This section outlines the limit value set for benzene concentrations.
Compliance against the benzene limit 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: Benzene compliance criteria
| Description | Averaging period | Metric |
|---|---|---|
| Benzene limit value for health | Annual mean | 5 µg/m3 |
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 modelling.
Modelling enables air quality to be assessed at locations without monitoring sites. It also provides additional information about the sources of pollution 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 33 monitoring stations from the Hydrocarbons Network which met the data quality requirements for assessment against the benzene limit value. This includes:
- 17 background stations
- 12 roadside monitoring stations
- 4 industrial monitoring stations
Modelling
The CMAQ-Urban Model was used for compliance assessment in 2025.
For assessment against the benzene limit value, 2 model outputs were calculated:
- annual average benzene concentration (µg/m3) for each 1x1km grid square of the UK
- annual average concentrations of benzene at the roadside for each major urban road in the UK
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 benzene limit value in 2025. 42 zones met the limit value for benzene and one – Yorkshire & Humberside – exceeded it.
This exceedance is reported from modelling. However, there is a significant level of uncertainty about the benzene concentrations modelled at complex industrial locations.
Modelled concentrations are higher than those modelled in previous years at this industrial location and also higher than historic measurements. In addition, one of the refinery installations in the vicinity of the modelled exceedance ceased operation in summer 2025. This is likely to have reduced benzene emissions in the area and could have led to the model overpredicting benzene concentrations in the area.
Work will commence at pace with the Environment Agency (as environmental regulators of the industrial sites) to investigate this exceedance and establish the accuracy of the modelling.
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. 2008 is the year that limit values for pollutants were set in the EU Air Quality Directive, which was subsequently transposed into UK legislation by the Air Quality Standards Regulations (2010).
The UK has been compliant with the limit value for benzene between 2008 and 2024 (inclusive) for all zones. 2025 is the first year that concentrations in any zone have been above the limit value.