Addressing ground-level ozone pollution in Europe

This overview of ground-level (or tropospheric) ozone pollution in Europe is based on data reported by EU Member States (EU-27) and is published in the context of the revised Ambient Air Quality Directive. Country-specific factsheets have been prepared for all EU-27 countries.

Key messages

Ozone affects human health and ecosystems; in 2023, 63,000 deaths could be attributed to it in the European Union (EU) and it caused billions of euros of damage due to crop losses.

Despite reductions in the emissions of pollutants that contribute to ozone, ground-level ozone levels have not decreased significantly.

The revised Ambient Air Quality (AAQ) Directive requires countries to take additional action to address the risks from ozone. Global action is also required to reduce transboundary pollution, which can limit the impact of national and local actions.

A deeper understanding of the role of different volatile organic compounds (VOCs) is required to identify the most effective mitigation measures to address ozone levels; this would also support the development of effective air quality plans for ozone.

Efforts to reduce nitrogen oxides (NO_X) should take into account international shipping emissions in addition to road traffic, particularly in coastal areas.

Understanding ozone formation

Ground-level ozone is a secondary pollutant; this means that it is not emitted directly but is formed in the atmosphere. To address its impacts effectively, it is essential to understand how it forms as well as its precursor emission sources and transport patterns.

As shown in Figure 1, ozoneis formed when sunlight initiates photochemical reactions between various precursors such as NO_X and VOCs. Temperature influences the rate of these reactions.

VOCs are diverse: they have different lifetimes in the atmosphere and different capacities to form ozone. They also originate from various sources. A significant proportion comes from biogenic emissions, both in the form of methane — emitted, for instance, by wetlands — and non-methane VOCs (NMVOCs) — emitted by vegetation.

Depending on the proportions of NO_X and VOCs, ozone in the atmosphere can be produced or destroyed (titration). This is why precursor emission reductions may not always lead to reductions in local ozoneconcentrations (ETC HE, 2025).

The chemical regime describes how ozone formation responds to changes in precursor emissions, indicating whether NO_X or VOC reductions are more effective for lowering ozone levels. It identifies regions as NO_X-sensitive, VOC-sensitive or transitional, depending on which precursor limits ozoneproduction (Real et al., 2024).

Figure 1. Ozone formation

Please select a resource that has a preview image available.

Lifetime and spatial scale are particularly relevant when considering methane mitigation and its impact on ozone levels. For example, methane contributes critically to hemispheric ozone, but local VOCs and NO_X play a significant role in ozone episodes (pollution peaks), as highlighted in the EEA methane, climate change and air quality in Europe briefing.

This current briefing focuses on the obligations introduced under the revised AAQ Directive (EU, 2024b). It also reviews recent trends in concentrations of ground-level ozone and the reduction in emissions of key ozoneprecursors. Additionally, it assesses existing air quality plans and provides country factsheets with key ozone-related information for each Member State.

Why is action on ozone necessary?

Ozone is a strong oxidant and can damage both human health and the environment. It also plays an important role in climate change, as it is a greenhouse gas (GHG) acting as a short-lived climate forcer (IPCC, 2023). In addition, ozone can contribute indirectly to climate change since it can negatively affect how much carbon dioxide can be absorbed by carbon sinks (EEA, 2025f).

Climate change is expected to worsen ozone pollution in Europe by increasing the frequency and intensity of heat-related meteorological conditions that enhance ozone formation (ETC HE, 2025). Moreover, the atmosphere’s oxidising capacity — which ozone helps to regulate — also affects the lifetime of methane, meaning that changes in ozone levels can also influence methane concentrations (Brasseur and Gaubert, 2025).

Health impacts

Ozone exposure is associated with respiratory disease and mortality both in the short and long term; in 2023, it caused an estimated 63,000 premature deaths in the EU-27 (EEA, 2025e). Ozone is the second leading cause of mortality among ambient air pollutants in the EU, after fine particulate matter (EEA, 2025e).

For regulatory purposes for the protection of human health, the ozone target value is defined as the maximum daily eight-hour mean (MDA8) in the EU. Under the revised AAQ Directive (EU, 2024b) this target value remains at 120 micrograms per cubic metre of air (µg/m³) (in line with the 2008 AAQ Directive (EU, 2008)) but the number of allowable exceedances has been reduced from 25 to 18 days per year, averaged over three years.

The revised AAQ Directive also strengthens the long-term objective for human health, aligning it with the World Health Organization (WHO) short-term eight-hour averaged guideline of 100µg/m³, to be achieved by 2050. In comparison, the 2008 directive set a long-term objective of 120µg/m³ as the MDA8.

In addition to the MDA8 value, the latest WHO Global Air Quality Guidelines (AQG) (WHO, 2021) includes a long-term peak-season AQG level of 60µg/m³based on evidence of the long-term effects of ozone on total mortality and respiratory mortality.

In 2023, ozone concentrations in the EU generally remained above the levels recommended by the WHO: 97% of those living in the EU’s urban areas were exposed to ozone concentrations above the peak-season AQG (EEA, 2025a). Reducing ozone levels to this WHO AQG could potentially have prevented around 63,000 premature deaths in the EU-27 in 2023 (EEA, 2025e).

Map 1 gives a visualisation of mortality attributable to long-term exposure to ozone in the EU-27 in 2023, expressed as years of life lost per 100,000 inhabitants. The countries with the highest mortality risk in 2023 were Hungary, Croatia, Lithuania, Latvia, Greece and Italy (in decreasing order).

Map 1. Mortality attributable to long-term exposure to ozone in 2023

Impacts on ecosystems

Ozone has significant impacts on vegetation, including agricultural crops and forests. It reduces the growth rates and yields of crops and has negative impacts on biodiversity and ecosystem services across Europe (EEA, 2024a). In 2023, 12.5% of Europe’s agricultural lands were exposed to ozone levels above the target value thresholdset for the protection of vegetation in both the revised AAQ Directive (EU, 2024b) and the 2008 AAQ Directive (EU, 2008). This target value, accumulated ozone exposure over a threshold of 40 parts per billion (AOT40), is set at 18,000μg/m³.hour, calculated over five years. In addition, the long-term objective, set at 6,000μg/m³.hour, was not met in 90.8% of agricultural lands (EEA, 2025d).

The phytotoxic ozone dose (POD), used under the United Nations Economic Commission for Europe (UNECE) Air Convention, estimates the ozone dose absorbed by plants through their stomata (CLRTAP, 2024). The EEA uses this metric to estimate ozone impacts on agricultural production and associated economic losses.

Crop losses in 2023 due to the impact of ozone across the EU-27 were estimated at over 17 million tonnes of wheat, corresponding to approximately EUR 3.75 billion in value. The highest relative wheat yield losses that year were estimated as being in Luxembourg (19.7%), Austria (17.7%), Belgium (17.7%) and Czechia (16.9%); they exceeded 4% in 20 EU countries.

The significance of the losses varies across regions, depending on the level of ozone and the absolute production of the respective crop. Absolute losses (Map 2) were highest in France (EUR 1,492 million) and Germany (EUR 837 million) (ETC HE, forthcoming).

Map 2. Crop losses due to the impact of ozone in 2023

Ozone trends

Ozone levels show strong geographical variability across Europe, with south and central Europe typically experiencing higher concentrations due to a combination of environmental and atmospheric conditions that strongly favour ozone formation. These include more intense solar radiation, higher temperatures and meteorological patterns that reduce dispersion and promote the accumulation of ozone and its precursors.

The long-term evolution of ozone concentrations in Europe is primarily influenced by three factors (ETC HE, 2025):

emissions of short-lived precursors (NO_X and NMVOCs) within Europe;
transboundary pollution, including methane, from outside Europe;
year-to-year meteorological variability.

Unlike other air pollutants, observed levels of ozone have not followed the downward trends seen for precursor emissions. Between 2005 and 2023, NO_X, NMVOC and methane emissions in Europe declined by around 53%, 35% and 22%, respectively (Figure 3). Over the same period, ozone peaks declined, while annual mean concentrations remained stable or increased (Figure 2).

More specifically, at rural EU-27 stations, annual average ozone concentrations increased by about 2%, while peak levels fell by 9%. Higher ozone concentrations are generally observed in rural areas compared to urban and suburban locations; this is due to atmospheric transport of ozone and precursors as well as a lower titration effect further from the sources.

At urban stations, annual average ozone rose by about 13% and ozone peaks decreased by 6%. At urban and suburban locations, decreasing NO_X emissions are expected to drive an increase in annual mean ozone concentrations, particularly where titration was previously dominant. Regional trends within Member States may diverge from this analysis of the European averages.

Figure 2. Ozone levels in EU-27, 2005-2023

Emission trends for ozone precursors

Interpreting emission trends in relation to ozone formation is challenging for a number of reasons:

ozone chemistry is nonlinear;
VOCs differ greatly in terms of their reactivity and lifetimes;
some biogenic NMVOC emissions, particularly those produced by vegetation and which can be considerable, are not reflected in emission inventories.

Member States report anthropogenic methane emissions under the Energy Governance Regulation (EU, 2018d) and NMVOC and NO_X emissions under the National Emission reduction Commitments (NEC) Directive (EU, 2016).

The accompanying European Topic Centre on Human Health and the Environment (ETC HE) report (ETC HE, 2026) presents a detailed analysis of emissions of the main ozone precursors (methane, NMVOC and NO_X), including a trend analysis by Member States for the 1990-2022 period detailing the underlying reasons for the relative change, trends by sectors, an analysis of relevant policies and measures at MS level, reflection on the methodologies used to calculate emissions, outlook on future emission trends, relevant policies at the EU level and recommendations on potential solutions to reduce precursors emissions.

Figure 3 presents the emission trends for these precursors (2005-2023) and the contribution of each EU‑27 Member State to total reported emissions in 2023. In the 2005-2023 period, Europe achieved substantial reductions in precursor emissions:

NO_X emissions fell by 53%;
NMVOCs by 35%;
methane by 22%.

France, Germany, Italy, Spain and Poland accounted for the largest shares of these emissions in 2023.

Figure 3. Emission trends for ozone precursors in the EU 27, 2005-2023, and emission shares by Member State, 2023

Methane

Among the ozone precursors, methane stands out for its significant climate impact, with a global warming potential 28 times higher than carbon dioxide, when considered over a 100‑year time horizon (IPCC, 2013). Cutting methane emissions could deliver rapid benefits for both climate and air quality due to the relatively short — for a GHG — atmospheric lifetime of methane of around 12 years.

All methane emissions, including from agricultural sources, are covered under the Effort Sharing Regulation (EU, 2018c). Emissions from the energy and waste sectors are targeted via the Regulation on the reduction of CH₄ emissions in the energy sector (EU, 2024c), the revised Industrial and Livestock Rearing Emissions Directive (IED2.0) and waste legislation. Regulation (EU) 2024/1787 (EU, 2024c) obliges fossil energy operators to measure and minimise emissions, while the expansion of biogas must be accompanied by strict leakage prevention measures. The IED2.0 (EU, 2024a) also regulates the release of methane from refineries, the chemical industry and large combustion plants, along with emissions from intensive pig and poultry production. Additionally, the common agricultural policy includes measures aimed at lowering overall GHG emissions, including methane.

Methane emissions from waste are tackled indirectly through the Waste Framework Directive (EU, 2018a), the Landfill Directive (EU, 1999) and other circular economy policies (EC, 2025b). Global mitigation efforts are also reflected in the Global Methane Pledge, a voluntary commitment launched at the 26th United Nations Climate Change Conference (COP26) by the EU and the United States to reduce global anthropogenic methane emissions by at least 30% from 2020 levels by 2030 (Climate and Clean Air Coalition, 2021).

EU‑27 methane emissions fell by 22% between 2005 and 2023 (41% between 1990 and 2023) (EEA, 2025b). The largest cuts came from the waste sector — supported by the EU Landfill Directive (EU, 2018b) — and from declining fugitive emissions linked to coal phase‑out and improved gas infrastructure (ETC HE, 2026).

Nonetheless, despite reductions in Europe, global atmospheric methane continues to rise; in 2023, it reached around 1,900 parts per billion (ppb), more than two and a half times pre-industrial levels (722 ppb) (Copernicus, 2023). This highlights the need for more stringent global measures.

Figure 4 indicates that agricultural activities and waste management were major contributors to methane emissions in EU Member States in 2023.

Figure 4. Methane emissions by sector in the EU‑27, 2023

Under the Energy Governance Regulation (EU, 2018d), Member States have reported more than 700 measures related to methane mitigation, mainly in agriculture and waste management. These include:

improved feeding practices and additives;
expanded biogas production from manure;
extended grazing;
organic farming;
separate biowaste collection;
reduced landfilling;
landfill gas recovery;
broader circular economy initiatives.

According to the Fourth Clean Air Outlook, NMVOC emissions are projected to have declined by 37% in 2030 relative to 2005 under the baseline scenario (EC, 2025c).

Further reductions could come from more systemic actions: dietary shifts that lower demand for meat and dairy, improved manure management and genetic selection, and tackling fugitive emissions from fossil fuel extraction through better monitoring and a progressive fossil fuel phaseout. In the waste sector, pretreatment of organic waste, aerated composting and closed anaerobic digestion can complement waste prevention measures to limit methane formation (ETC HE, 2026).

NMVOCs

NMVOCs play a major role in shaping the oxidation capacity of the atmosphere and in tropospheric air quality, as they contribute to the formation of ozone and secondary organic aerosols. In emission inventories, total anthropogenic NMVOCs are reported as an aggregate and no speciation is generally available.

A range of EU and international policies address NMVOC emissions, either directly or indirectly, to reduce the formation of ozone. At the continental scale, the amended Gothenburg Protocol to Abate Acidification, Eutrophication and Ground-level Ozone under the UNECE Air Convention establishes national emission reduction commitments for sulphur dioxide, NO_X, NMVOCs and ammonia for the year 2020 and beyond (UNECE, 2012).

At the EU level, the NEC Directive (EU, 2016) establishes binding national reduction commitments for five pollutants, including NMVOCs; these are aligned with those of the amended Gothenburg Protocol under the UNECE Air Convention. Additional EU legislation supports NMVOC mitigation. This includes:

IED 2.0 (EU, 2024a), which aims to prevent industrial pollution and promotes investment in cleaner and more innovative techniques;
the Paints Directive (EU, 2021), which limits VOC content in paints, varnishes and vehicle refinishing products to reduce emissions from consumer use;
the Fuel Quality Directive (EC, 2009) which sets strict fuel quality requirements, such as limits on aromatic compounds and polycyclic aromatic hydrocarbons.

EU-27 NMVOC emissions decreased by 35% between 2005 and 2023 (63% between 1990 and 2023) (EEA, 2025h), with all Member States reporting reductions. While road transport was the main source of NMVOCs in 1990, residential heating (mainly wood burning), solvent use, coating applications, other industrial processes and manure management accounted for 78% of EU NMVOC emissions in 2023 (Figure 5).

Figure 5. NMVOC emissions by sector in the EU‑27, 2023

Nearly 500 measures related to NMVOCs have been reported (EEA, 2024b), focusing on:

expanding renewable energy;
improving building efficiency;
switching to lower-carbon fuels;
applying abatement technologies.

According to the Fourth Clean Air Outlook, NMVOC emissions are projected to have declined by 52% in 2030 relative to 2005 emissions under the baseline scenario (EC, 2025c).

Additional mitigation potential lies in transforming energy systems and product use. Replacing fossil fuel-based residential heating with renewable energy-based technologies and deep renovation can reduce emissions linked to combustion and products containing solvents. In industry, wider adoption of best available technologies and low solvent formulations would also decrease emissions. Further gains could be achieved by reducing the use of domestic products that contain VOCs. Additionally, agriculture contributes to NMVOCs, so improvements in manure management and reducing the consumption of animal products would lower these emissions.

NOx

NO_X include nitric oxide (NO) and nitrogen dioxide (NO₂); they originate mainly from fuel combustion. Various measures regulate these pollutants at the EU level, including:

The amended Gothenburg Protocol (UNECE, 2012) has established international commitments.
The NEC Directive (EU, 2016) sets binding national emission reduction commitments.
IED2.0 (EU, 2024a) promotes best available techniques.
The Medium Combustion Plants Directive (EU, 2015) sets emission limits.
European emission standards (EU, 2005) regulate road vehicle emissions.

Figure 6 indicates that in 2023 emissions of these pollutants mainly related to transport, energy production and agriculture. EU-27 NO_X emissions decreased by 53% between 2005 and 2023 (67% between 1990 and 2023) (EEA, 2025h), with all Member States reporting reductions.

Figure 6 NO_x emissions by sector in the EU‑27, 2023

Figure 6 is derived from totals for emissions reported by Member States based on the data required by the NEC Directive (EU, 2016), so it does not reflect the contribution from international shipping and aviation. Excluding emissions from international maritime sources may not provide an accurate reflection of the extent to which shipping activities affect concentrations of air pollutants (EC, 2025b).

NO_X emissions reported by Member States in 2023 for shipping and aviation totalled 1,561 kilotonnes (kt) (1,055.2 kt for shipping and 506 kt from aviation); these were higher than the total for road transport (1,426 kt) (EEA, 2025g). This is particularly relevant in coastal areas (EC, 2025b), specifically in the Mediterranean where higher concentrations occur.

Furthermore, the relative contribution from different sectors is expected to change in the coming years. Shipping emissions are projected to surpass road traffic as the leading source of transport air pollution in coastal cities by 2030 (EEA and EMSA, 2025).

Member States have reported more than 500 measures related to NO_X (EEA, 2024b), primarily targeting transport and energy. Current strategies include:

demand management;
promoting alternative fuels and electric vehicles;
shifting to public transport and improving transport infrastructure.

Industrial installations already widely apply abatement technologies such as selective catalytic reduction and exhaust gas recirculation. According to the Fourth Clean Air Outlook, NO_X emissions are projected to have declined by 73% in 2030 relative to 2005 emissions under the baseline scenario (EC, 2025c).

Long-term reductions, however, will require further structural changes such as (ETC HE, 2026):

replacing fossil fuels with renewable energy to eliminate NO_X formation from combustion;
accelerating electrification of the vehicle fleet;
reducing car dependence through sustainable urban planning;
expanding high-quality public transport networks.

Current air quality plans for ozone

Under the 2008 AAQ Directive (EU, 2008), Member States were required to take all necessary measures to meet the target values and long-term objectives — as long as they did not entail disproportionate costs. Member States were also required to set out measures for reducing precursor (NMVOC and NO_X) emissions in the programmes prepared under the NEC Directive (EU, 2016).

However, it was not mandatory to prepare dedicated ozone air quality plans. Only limited information on ozone-specific air quality plans is currently available in the EEA database. To address this gap, an Eionet consultation was launched in 2025 within the Eionet Thematic Group on Air to collect information on national and regional ozone plans, ongoing scientific studies and policies targeting ozone pollution across EEA member countries.

Twelve countries responded. Of these, only Croatia, France and Spain have developed or implemented air quality plans explicitly focused on ozone. Most participating countries reported scientific work aimed at improving forecasting for ozone concentration, understanding formation processes, assessing precursor contributions and conducting source apportionment. Several also reported communication and public-awareness initiatives.

Croatia has developed ozone action plans for the cities of Rijeka (OIKON, 2016) and Pula (OIKON, 2022); it has implemented additional measures in cities such as Pićan, Labin and Zagreb. Several municipalities also have protocols for ozone exceedances of the information and alert thresholds. The Pula plan includes measures targeting traffic, port operations, shoreside electricity for ships and energy efficiency. Monitoring data indicate a slight reduction in the number of days above the target value to protect human health in the 2019-2023 period (ETC HE, 2026).

France addresses ozone within its regional atmosphere protection plans (PPAs) and territorial climate air energy plans (PCAETs), which follow a multipollutant approach. Some PPAs include measures specifically focused on reducing NMVOC emissions. For example, the Strasbourg PPA includes one NMVOC-related action, while the Bouches du Rhône and Var (PACA region) PPA include measures to control industrial NMVOC emissions and improve understanding of ozone formation and its climate impacts. Since 2012, most French regions have reported ozone-related measures to the EEA.

Spain is affected by high ozone levels and has commissioned an in-depth scientific assessment to support the development of the upcoming National Ozone Plan (MITECO, 2026). The study (MITECO, 2025) classifies Spain into four ozone basins or regions (R1-R4) based on ozone pollution patterns.

R1 and R2 have the lowest ozone levels and are mainly affected by long-range transport. R3 and R4 include the country’s main hotspots, where exceedances are driven by strong local formation.

The study identifies the NMVOCs most relevant for ozone formation in each basin and shows, through modelling, that reducing emissions of ozone precursors generated by road traffic and maritime transport are key to lowering ozone concentrations. It also states that national measures alone are insufficient to meet the long-term EU objective without coordinated international action, such as the inclusion of methane in the Gothenburg Protocol and designating the Mediterranean as an Emission Control Area for NO_X (MITECO, 2026).

Additional ozone measures under the revised AAQ Directive

The revised AAQ Directive (EU, 2024b) establishes stricter air quality standards, expands monitoring obligations for ozone and its precursors, and reinforces requirements for air quality plans and cooperation on transboundary pollution. The stricter ozone target values applicable from 2030 are likely to lead to a higher number of exceedances, as indicated by the benchmark analysis against the standards in the revised AAQ Directive.

Expanded monitoring requirements for ozone

For ozone, the minimum number of sampling points based on population is unchanged in the revised AAQ Directive (EU, 2024b), but the required number of monitoring stations has been affected, for two main reasons.

First, the assessment threshold has been lowered to 100μg/m³ (maximum eight-hour mean) aligning it with the WHO short‑term ozone AQG (WHO, 2021). Second, there is no longer a differentiation on the minimum number of sampling points required for agglomerations and other air zones (suburban or rural).

An analysis for Germany, the Netherlands, Norway and Spain shows that these changes will increase the need for sampling points. This is particularly the case in densely populated zones (ETC HE, 2026).

Expanded monitoring requirements for VOC precursors

The revised AAQ Directive (EU, 2024b) substantially broadens the list of VOCs that could be monitored, from 30 to 46 species, including methane. This expansion reflects the need for a more complete understanding of ozone formation, including the role of biogenic emissions and oxygenated compounds. The explicit inclusion of methane acknowledges its growing relevance in ozone production.

Monitoring VOCs serves several purposes, including:

tracking temporal trends;
assessing emission reduction policies;
verifying inventories;
improving understanding of ozone and secondary organic aerosol formation;
validating models;
identifying major emission sources.

The reactivity, and therefore the atmospheric lifetime, of VOCs varies widely and this factor significantly affects their impact on ozone concentration. An ETC HE study (ETC HE, 2026) provides an analysis of all the VOCs listed in Annex VII of the revised AAQ Directive (EU, 2024b), including their atmospheric lifetimes, ozone formation potential expressed as maximum incremental reactivity (MIR) and their relevance for atmospheric processes. This information is essential for determining which NMVOCs are most relevant in different regions, depending on local emission sources, chemical regimes and meteorological conditions.

It also highlights the need to monitor both short-lived VOCs — which drive local ozone formation — and long-lived species — which influence background levels and remote oxidation capacity. Measures to address ozone can be made more effective and targeted by utilising this more detailed information on specific VOCs and their contributions to ozone formation.

At the European level, domestic solvent use, coating applications and other industrial processes accounted for 42.7% of EU NMVOC emissions in 2023 (Figure 5). When focusing specifically on solvent use and coating applications, monitoring strategies should prioritise BTEX, trimethylbenzenes and key ketones in urban and industrial areas (EEA, 2023). These compounds are highly relevant for ozone formation and are robust indicators of anthropogenic sources.

The ETC HE report (ETC HE, 2026) also recommends implementing BTEX monitoring more broadly across Europe, as these compounds pose a significant health burden (Bolden et al., 2015), have high ozone formation potential and are good indicators of petrochemical and wood-burning emissions. Additional specialised monitoring may be needed for biogenic VOCs (e.g. terpenes), although their reactivity means that it is costly to measure them.

Multiple instruments, specialised expertise and access to calibration standards are required to monitor all the recommended VOCs. This contributes to disparities in measurement capacity across Member States.

A technical support document on the use of reference and non-reference methods (EC, 2025a) provides an overview of current knowledge and best practices for air quality monitoring for NMVOCs. Additionally, a European Committee for Standardization (CEN) standard is currently being developed, supported by EU funding (EC, 2019), to harmonise the measurement of VOCs included in the 2008 Directive (EU, 2008).

Satellite remote sensing, combined with inverse modelling, is essential for tracking VOC distributions. Methane and formaldehyde are currently measured from space, but limited formaldehyde observations hinder the validation of data derived from satellites. Expanding in-situ monitoring would strengthen both modelling and satellite analyses. For methane, monitoring should focus on agricultural regions with high livestock density (as agriculture remains the dominant source, with enteric fermentation contributing the largest share of emissions), growing biogas infrastructure, landfills and areas with remaining fossil fuel production infrastructure.

Refining the approach to VOC monitoring

Current reporting to the EEA (EEA, 2026) is dominated by aromatic hydrocarbons, particularly benzene — as would be expected for a regulated pollutant — and toluene. Methane, oxygenates (formaldehyde) and highly reactive species (isoprene, α-pinene) remain insufficiently monitored. Overall, the number of NMVOC time series being reported has declined over the past decade. Only a few highly reactive species, such as toluene and m,p-xylene, are measured consistently.

Programmes have played a pivotal role in establishing systematic observations of VOCs; such as the Co-operative Programme for Monitoring and Evaluation of the Long-range Transmission of Air Pollutants in Europe (EMEP) (EMEP, 2026) and the VOC monitoring activities under the Global Atmosphere Watch Programme (GAW) (WMO, 2025). EMEP, GAW and more recently the Aerosol, Clouds, and Trace Gases Research Infrastructure (ACTRIS) (ACTRIS, 2026) have been instrumental in developing measurement methodologies and quality assurance/quality control procedures for VOC observations in regional and remote areas across Europe. Data from all these programmes are included in the EBAS database.

Germany is currently the only country that reports methane concentrations to the EEA e-reporting air quality database on a voluntary basis. However, existing research infrastructures already provide a strong basis for expanding methane monitoring: ICOS delivers high-quality GHG observations, EMEP (EMEP, 2026) and GAW (WMO, 2025) ensure long-term background measurements, and the Total Carbon Column Observing Network (TCCON) offers essential reference data for validating satellite‑derived products.

In this context, a tiered VOC monitoring network that integrates different levels of measurement complexity and fully leverages existing infrastructures and tools could offer the most effective approach (ETC HE, 2026). Such a network would enable Member States to strengthen their understanding of the key drivers of ozone formation. It would also allow Member States to better support the development of robust ozone mitigation strategies across Europe. This tiered network should combine different approaches including:

core continuous monitoring sites (e.g. urban and regional background stations such as the new supersites) equipped with advanced online instruments for targeted NMVOC speciation (BTEX, trimethylbenzenes, key alkenes (ethylene, propene, 1,3‑butadiene), ketones (e.g. acetone), formaldehyde and methane) supported by protocols from ACTRIS, EMEP and GAW;
supplementary low-cost sites to enhance spatial coverage for relevant VOCs in each specific region/country;
integration with European research infrastructure to optimise costs, ensure methodological harmonisation and maintain the continuity of long-term data;
combined use of satellite and ground-based observations, supported by inverse modelling, to expand spatial coverage and enable top-down verification of emission inventories.

Overall, establishing a more effective European VOC monitoring system is technically feasible, but would require (ETC HE, 2026):

key precursors to be prioritised;
methane and formaldehyde observations to be expanded;
coverage of highly reactive VOCs in both urban and rural environments to be improved.

Air quality plans for ozone

The revised AAQ Directive (EU, 2024b) maintains the link with precursor reduction measures under the NEC Directive (EU, 2016); however, it also introduces a new mandatory requirement for ozone-specific air quality plans and roadmaps. Member States must prepare these plans unless they can demonstrate either of the following conditions:

There is no significant potential to reduce ozone levels due to geographical or meteorological conditions.
Available measures would involve disproportionate costs.

If an air quality plan or roadmap is not prepared, Member States must provide a detailed, publicly available justification explaining why ozone reductions are not achievable. This justification must also be submitted to the European Commission and updated at least every five years.

For these plans, the revised AAQ Directive (EU, 2024b) refers to territorial units, which may include several air quality zones. This approach acknowledges that reducing local precursor emissions does not always translate into lower local ozone levels and that effective action often requires coordinated measures at a regional or broader geographic scale.

Short-term action plans must also be prepared. These must set out emergency measures to reduce the immediate risk or shorten the duration of any exceedance of the ozone alert threshold.

Air quality plans for ozone must include a source apportionment analysis that identifies the main emission sources responsible for exceedances, quantifies their emissions and assesses their contribution at the city, regional, national and transboundary scales. These analyses must be based on information from the NEC Directive (EU, 2016) and national air pollution control programmes.

A cross-cutting review shows that most existing plans lack ozone-specific approaches and insufficiently account for transboundary contributions. This reflects the complexity of the nonlinear chemistry of ozone and the need for stronger European coordination (ETC HE, 2026).

Transboundary contributions

The revised AAQ Directive (EU, 2024b) recognises that ozone pollution is inherently transboundary by establishing clearer mechanisms for notification, cooperation and coordinated action between Member States. This broader approach is essential given that local reductions in emissions alone are often insufficient to achieve ozone targets.

Tools for developing air quality plans

To support more effective planning, tools such as the CAMS Policy Support Service Air Control Toolbox (ACT) (Colette et al., 2022) can offer daily diagnostics for major European cities. It can attribute ozone-related impacts to traffic, industrial, residential, agricultural, shipping and other sources of emissions (including solvents, aviation, offroad, waste and the Gridded Nomenclature for Reporting (GNFR) sector ‘others’).

Based on this tool, a new dashboard allows interactive browsing through the sectoral contributions to ozone in the updated EEA city viewer (EEA, 2025c). The dashboard extracted ozone source contributions for the cities included in the burden of disease assessment (EEA, 2025e), using 2024 data and the ozone peak‑season indicator.

Furthermore, the EU-27 country factsheets , developed by the ETC HE, provide a comprehensive overview of the state, trends and future projections of ozone concentrations in each Member State. They draw on validated monitoring data and modelling tools, such as CHIMERE and the EMEP/MSC‑W chemistry‑transport models to present a range of information including:

long‑term ozone concentration trends at the national level (2005-2023);
changes in precursor emissions (NO_X, NMVOCs and methane);
an example of sectoral contributions to the station with the highest ozone concentration (peak season and peak MDA8) and transboundary contributions at the national level;
analyses of chemical regimes at air quality stations exceeding the ozone target value to protect human health and projections to 2050 under different emission scenarios.

Taken together, these country factsheets could help identify the key drivers of ozone pollution, highlight priority sectors for mitigation and allow for the assessment of the potential for ozone reduction at the national level.

EEA Briefing 08/2026:

Title: Addressing ground-level ozone pollution in Europe

HTML: TH-01-26-019-EN-Q - ISBN: 978-92-9480-773-1 - ISSN: 2467-3196 - doi: 10.2800/7093761

The European Environment Agency (EEA) would like to thank its partners from the European Environment Information and Observation Network (EEA member countries and European Topic Centres) for their valuable contributions and input.

ACTRIS, 2026, ‘| ACTRIS’ (https://actris.eu/) accessed 27 January 2026.

Bolden, A. L., et al., 2015, ‘New Look at BTEX: Are Ambient Levels a Problem?’, Environmental Science & Technology 49(9), pp. 5261-5276 (DOI: 10.1021/es505316f).

Brasseur, G. P. and Gaubert, B., 2025, ‘The atmospheric oxidizing capacity and the methane budget’, National Science Review 12(9), p. nwaf347 (DOI: 10.1093/nsr/nwaf347).

Climate and Clean Air Coalition, 2021, ‘Global Methane Pledge: Fast action on methane to keep a 1.5°C future within reach’ (https://www.globalmethanepledge.org/) accessed 3 February 2026.

CLRTAP, 2024, Manual on Methodologies and Criteria for Modelling and Mapping Critical Loads and Levels and Air Pollution Effects, Risks, and Trends - Update 2024,.

Colette, A., et al., 2022, ‘Air Control Toolbox (ACT_v1.0): a flexible surrogate model to explore mitigation scenarios in air quality forecasts’, Geoscientific Model Development 15(4), pp. 1441-1465 (DOI: 10.5194/gmd-15-1441-2022).

Copernicus, 2023, ‘Greenhouse gas concentrations’, Observations of greenhouse gases (https://climate.copernicus.eu/esotc/2023/greenhouse-gas-concentrations) accessed 3 February 2026.

EC, 2009, Directive 2009/30/EC of the European Parliament and of the Council of 23 April 2009 amending Directive 98/70/EC as regards the specification of petrol, diesel and gas-oil and introducing a mechanism to monitor and reduce greenhouse gas emissions and amending Council Directive 1999/32/EC as regards the specification of fuel used by inland waterway vessels and repealing Directive 93/12/EEC (Text with EEA relevance) (OJ L).

EC, 2019, Commission implementing decision on a standardisation request to the European Committee for Standardisation as regards methods for the measurement of volatile organic compounds that are ozone precursor substances in ambient air in support of Directive 2008/50/EC of the European Parliament and of the Council ( C(2019)4281), (https://ec.europa.eu/transparency/documents-register/detail?ref=C(2019)4281&lang=en).

EC, 2025a, Air quality monitoring for air quality policy: technical support document on the use of reference and non reference methods, and on the quality assurance process to meet relevant data quality objectives for regulated air pollutants: final version, Publications Office of the European Union (https://data.europa.eu/doi/10.2779/6569975) accessed 15 January 2026.

EC, 2025b, Evaluation of the National Emission Reduction Commitments Directive, (https://environment.ec.europa.eu/publications/evaluation-national-emission-reduction-commitments-directive_en) accessed 23 March 2026.

EC, 2025c, Support to the development of the fourth clean air outlook: final report, Publications Office of the European Union (https://data.europa.eu/doi/10.2779/8768689) accessed 18 March 2026.

EEA, 2023, EMEP/EEA air pollutant emission inventory guidebook 2023, EEA Report No 06/2023 (https://www.eea.europa.eu/en/analysis/publications/emep-eea-guidebook-2023) accessed 26 January 2026.

EEA, 2024a, ‘Impacts of air pollution on ecosystems in Europe’ (https://www.eea.europa.eu/en/analysis/publications/impacts-of-air-pollution-on-ecosystems-in-europe) accessed 2 February 2026.

EEA, 2024b, ‘National Emission reduction Commitments Directive — Policies and Measures (PaMs) to reduce air pollutants emissions’ (https://www.eea.europa.eu/en/analysis/maps-and-charts/overview-of-compliant-air-pollution-policies-dashboards) accessed 20 March 2026.

EEA, 2025a, Air quality status report 2025 (https://www.eea.europa.eu/en/analysis/publications/air-quality-status-report-2025/ozone) accessed 10 February 2026.

EEA, 2025b, ‘EEA greenhouse gases’ (https://www.eea.europa.eu/en/analysis/maps-and-charts/greenhouse-gases-viewer-data-viewers) accessed 25 March 2026.

EEA, 2025c, ‘European city air quality viewer’ (https://www.eea.europa.eu/en/topics/in-depth/air-pollution/european-city-air-quality-viewer) accessed 20 January 2026.

EEA, 2025d, ‘Exposure of Europe’s ecosystems to ozone’ (https://www.eea.europa.eu/en/analysis/indicators/exposure-of-europes-ecosystems-to-ozone) accessed 2 February 2026.

EEA, 2025e, ‘Harm to human health from air pollution in Europe: burden of disease status, 2025’ (https://www.eea.europa.eu/en/analysis/publications/harm-to-human-health-from-air-pollution-burden-of-disease-status-2025) accessed 12 January 2026.

EEA, 2025f, ‘Methane, climate change and air quality in Europe: exploring the connections’ (https://www.eea.europa.eu/en/analysis/publications/methane-climate-change-and-air-quality-in-europe-exploring-the-connections) accessed 12 January 2026.

EEA, 2025g, ‘National air pollutant emissions data viewer 2005-2023’ (https://www.eea.europa.eu/en/topics/in-depth/air-pollution/national-air-pollutant-emissions-data-viewer-2005-2023) accessed 25 March 2026.

EEA, 2025h, National Emission reductions Commitments (NEC) Directive emission inventory data, 1980-2023 ver 2.0, (https://sdi.eea.europa.eu/catalogue/srv/api/records/b35bb038-6ba6-46c2-a66f-0592e5385b10?language=all) accessed 25 March 2026, European Environment Agency.

EEA, 2026, ‘Air Quality Download Service’ (https://eeadmz1-downloads-webapp.azurewebsites.net/) accessed 3 February 2026.

EEA and EMSA, 2025, European Maritime Transport Environmental Report 2025, EEA-EMSA Joint Report No 15/2024 (https://www.eea.europa.eu/en/analysis/publications/maritime-transport-2025) accessed 15 June 2025.

EMEP, 2026, ‘EMEP’ (https://emep.int/) accessed 27 January 2026.

ETC HE, 2025, European surface ozone: the potential of mitigating methane and other precursors, ETC HE Report No 2024/16 (https://www.eionet.europa.eu/etcs/etc-he/products/etc-he-products/etc-he-reports/etc-he-report-2024-16-european-surface-ozone-the-potential-of-mitigating-methane-and-other-precursors) accessed 5 February 2025.

ETC HE, 2026, Ozone levels in relation to its precursors: NOx, NMVOCs and CH4, ETC HE Report No 2025/12 (https://www.eionet.europa.eu/etcs/etc-he/products/etc-he-products/etc-he-reports/etc-he-report-2025-12-ozone-levels-in-relation-to-its-precursors-nox-nmvocs-and-ch4/view).

ETC HE, forthcoming, Wheat and potato yield loss in 2023 in Europe due to ozone exposure, ETC HE Report 2026.

EU, 1999, Council Directive 1999/31/EC of 26 April 1999 on the landfill of waste (OJ L 182, 16.7.1999, pp. 1-19).

EU, 2005, Commission Directive 2005/78/EC of 14 November 2005 implementing Directive 2005/55/EC of the European Parliament and of the Council on the approximation of the laws of the Member States relating to the measures to be taken against the emission of gaseous and particulate pollutants from compression-ignition engines for use in vehicles, and the emission of gaseous pollutants from positive ignition engines fuelled with natural gas or liquefied petroleum gas for use in vehicles and amending Annexes I, II, III, IV and VI thereto (OJ L 313, 29.11.2005, pp. 1-93).

EU, 2008, Directive 2008/50/EC of the European Parliament and of the Council of 21 May 2008 on ambient air quality and cleaner air for Europe (OJ L 152, 11.6.2008, pp. 1-44).

EU, 2015, Directive (EU) 2015/2193 of the European Parliament and of the Council of 25 November 2015 on the limitation of emissions of certain pollutants into the air from medium combustion plants (OJ L 313, 28.11.2015, pp. 1-19).

EU, 2016, Directive (EU) 2016/2284 of the European Parliament and of the Council of 14 December 2016 on the reduction of national emissions of certain atmospheric pollutants, amending Directive 2003/35/EC and repealing Directive 2001/81/EC (OJ L 344, 17.12.2016, pp. 1-31).

EU, 2018a, Directive 2008/98/EC of the European Parliament and of the Council of 19 November 2008 on waste and repealing certain Directives (OJ L 312 22.11.2008, p. 3).

EU, 2018b, Directive (EU) 2018/850 of the European Parliament and of the Council of 30 May 2018 amending Directive 1999/31/EC on the landfill of waste (OJ L 150, 14.6.2018, pp. 100-108).

EU, 2018c, Regulation (EU) 2018/842 of the European Parliament and of the Council of 30 May 2018 on binding annual greenhouse gas emission reductions by Member States from 2021 to 2030 contributing to climate action to meet commitments under the Paris Agreement and amending Regulation (EU) No 525/2013 (OJ L 156, 19.6.2018, pp. 26-42).

EU, 2018d, Regulation (EU) 2018/1999 of the European Parliament and of the Council of 11 December 2018 on the Governance of the Energy Union and Climate Action, amending Regulations (EC) No 663/2009 and (EC) No 715/2009 of the European Parliament and of the Council, Directives 94/22/EC, 98/70/EC, 2009/31/EC, 2009/73/EC, 2010/31/EU, 2012/27/EU and 2013/30/EU of the European Parliament and of the Council, Council Directives 2009/119/EC and (EU) 2015/652 and repealing Regulation (EU) No 525/2013 of the European Parliament and of the Council (OJ L 328, 21.12.2018, pp. 1-77).

EU, 2021, Directive 2004/42/EC of the European Parliament and of the Council of 21 April 2004 on the limitation of emissions of volatile organic compounds due to the use of organic solvents in certain paints and varnishes and vehicle refinishing products and amending Directive 1999/13/EC (OJ L 143 30.4.2004, p. 87).

EU, 2024a, Directive 2010/75/EU of the European Parliament and of the Council of 24 November 2010 on industrial and livestock rearing emissions (integrated pollution prevention and control) (Recast) (OJ L 334 17.12.2010, p. 17).

EU, 2024b, Directive (EU) 2024/2881 of the European Parliament and of the Council of 23 October 2024 on ambient air quality and cleaner air for Europe (recast) (OJ L, 2024/2881, 20.11.2024).

EU, 2024c, Regulation (EU) 2024/1787 of the European Parliament and of the Council of 13 June 2024 on the reduction of methane emissions in the energy sector and amending Regulation (EU) 2019/942 (OJ L, 2024/1787, 15.7.2024).

IPCC, 2013, Climate Change 2013: The Physical Science Basis (https://www.ipcc.ch/report/ar5/wg1/).

IPCC, 2023, Climate Change 2021: The Physical Science Basis, Working Group I Contribution to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press (https://www.ipcc.ch/report/ar6/wg1/).

MITECO, 2025, Bases cientifícas para un Plan Nacional de Ozono: Resumen de los resultados de las investigaciones realizadas entre 2019 y 2024 (https://libreria.miteco.gob.es/libro/bases-cientificas-para-un-plan-nacional-de-ozono-2019-2024_3390/) accessed 15 January 2026.

MITECO, 2026, Plan Nacional de Ozono (https://www.miteco.gob.es/content/dam/miteco/es/calidad-y-evaluacion-ambiental/sgalsi/atm%c3%b3sfera-y-calidad-del-aire/participaci%c3%b3n-p%c3%bablica-/calidad-del-aire/Proyecto%20de%20un%20Plan%20Nacional%20de%20Ozono.pdf).

OIKON, 2016, Action Plan for the Reduction of ground-level ozone pollution in the City of Rijeka (https://www.rijeka.hr/wp-content/uploads/2016/04/Akcijski-plan-za-smanjenje-one%C4%8Di%C5%A1%C4%87enja-prizemnim-ozonom-za-grad-Rijeku-.pdf) accessed 19 January 2026.

OIKON, 2022, Action Plan for the Reduction of ground-level ozone pollution for City of Pula (https://www.pula.hr/media/filer_public/96/03/9603d1f5-46e8-4aaf-a808-d40b8434c940/akcijski_plan_ozon_grad_pula_svibanj_2022_zadnje.pdf) accessed 19 January 2026.

Real, E., et al., 2024, ‘Atlas of ozone chemical regimes in Europe’, Atmospheric Environment 320, p. 120323 (DOI: 10.1016/j.atmosenv.2023.120323).

UNECE, 2012, 1999 Protocol to Abate Acidification, Eutrophication and Ground-level Ozone to the Convention on Long- range Transboundary Air Pollution, as amended on 4 May 2012 (ECE/EB.AIR/114), (https://unece.org/sites/default/files/2021-10/ECE.EB_.AIR_.114_ENG.pdf).

WHO, 2021, ‘WHO Global Air Quality Guidelines’ (https://www.who.int/publications/i/item/9789240034228) accessed 28 January 2026.

WMO, 2025, ‘Global Atmosphere Watch Programme (GAW)’, World Meteorological Organization (https://community.wmo.int/site/knowledge-hub/programmes-and-initiatives/global-atmosphere-watch-programme-gaw) accessed 27 January 2026.

set of chemically and physically reactive compounds with atmospheric lifetimes typically shorter than two decades.
^↵
Applicable from 2030.
^↵
99th percentile, i.e. three exceedance days per year.
^↵
Average of MDA8 mean ozone concentration in the six consecutive months with the highest six-month running average ozone concentration.
^↵
The threshold target value is based on a one-year average, not over five years.
^↵
The peak is expressed as the fourth highest value of the eight-hour mean (4MDA8).
^↵
The baseline scenario is consistent with the projected evolution of the energy system in the 2040 climate target assessment and includes the latest EU and national legislation and plans.
^a^b^c
practice of deriving information about pollution sources and the amount they contribute to ambient air pollution levels.
^↵
180μg/m³ to be measured over one hour.
^↵
240μg/m³ to be measured over one hour.
^↵
The level that determines when a fixed sampling point is required.
^↵
99th percentile, i.e. three exceedance days per year.
^↵
Cities or built‑up areas with more than 250,000 inhabitants or smaller areas with a high population density.
^↵
BTEX is a group of VOCs that comprises benzene, toluene, ethylbenzene and xylene.
^↵
These are air quality plans that would need to be adopted ahead of the attainment deadline of limit values and target values and set out policies and measures to comply with those limit values and target values within the attainment deadline.
^↵