Judgment of the Court (First Chamber) of 26 June 2019

Judgment

1 This request for a preliminary ruling concerns the interpretation of Article 4(3) TEU and the second subparagraph of Article 19(1) TEU, read in conjunction with the third paragraph of Article 288 TFEU, and of Articles 6, 7, 13 and 23 of and Annex III to 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 2008 L 152, p. 1).

2 The request has been made in the context of a dispute between Ms Lies Craeynest, Ms Cristina Lopez Devaux, Mr Frédéric Mertens, Mr Stefan Vandermeulen, Ms Karin De Schepper and ClientEarth VZW, on the one hand, and the Brussels Hoofdstedelijk Gewest (Brussels Capital Region, Belgium) and the Brussels Instituut voor Milieubeheer (Brussels Institute for Environmental Management, Belgium), on the other, regarding the obligation to develop an air quality plan for the Brussels zone (Belgium) and to install the sampling points legally required to monitor air quality.

Legal context

3 Recitals 2, 5 to 7 and 14 of Directive 2008/50 state:

‘(2) In order to protect human health and the environment as a whole, it is particularly important to combat emissions of pollutants at source and to identify and implement the most effective emission reduction measures at local, national and Community level. Therefore, emissions of harmful air pollutants should be avoided, prevented or reduced and appropriate objectives set for ambient air quality taking into account relevant World Health Organisation standards, guidelines and programmes.

…

(5) A common approach to the assessment of ambient air quality should be followed according to common assessment criteria. When assessing ambient air quality, account should be taken of the size of populations and ecosystems exposed to air pollution. It is therefore appropriate to classify the territory of each Member State into zones or agglomerations reflecting the population density.

(6) Where possible modelling techniques should be applied to enable point data to be interpreted in terms of geographical distribution of concentration. This could serve as a basis for calculating the collective exposure of the population living in the area.

(7) In order to ensure that the information collected on air pollution is sufficiently representative and comparable across the Community, it is important that standardised measurement techniques and common criteria for the number and location of measuring stations are used for the assessment of ambient air quality. Techniques other than measurements can be used to assess ambient air quality and it is therefore necessary to define criteria for the use and required accuracy of such techniques.

…

(14) Fixed measurements should be mandatory in zones and agglomerations where the long-term objectives for ozone or the assessment thresholds for other pollutants are exceeded. Information from fixed measurements may be supplemented by modelling techniques and/or indicative measurements to enable point data to be interpreted in terms of geographical distribution of concentrations. The use of supplementary techniques of assessment should also allow for reduction of the required minimum number of fixed sampling points.’

4 Article 1 of Directive 2008/50 provides:

‘This Directive lays down measures aimed at the following:

1. defining and establishing objectives for ambient air quality designed to avoid, prevent or reduce harmful effects on human health and the environment as a whole;

2. assessing the ambient air quality in Member States on the basis of common methods and criteria;

3. obtaining information on ambient air quality in order to help combat air pollution and nuisance and to monitor long-term trends and improvements resulting from national and Community measures;

…’

5 Article 2 of that directive provides:

‘For the purposes of this Directive:

…

1. “level” shall mean the concentration of a pollutant in ambient air or the deposition thereof on surfaces in a given time;

2. “assessment” shall mean any method used to measure, calculate, predict or estimate levels;

3. “limit value” shall mean a level fixed on the basis of scientific knowledge, with the aim of avoiding, preventing or reducing harmful effects on human health and/or the environment as a whole, to be attained within a given period and not to be exceeded once attained;

…

1. “agglomeration” shall mean a zone that is a conurbation with a population in excess of 250 000 inhabitants or, where the population is 250 000 inhabitants or less, with a given population density per km² to be established by the Member States;

…

1. “average exposure indicator” shall mean an average level determined on the basis of measurements at urban background locations throughout the territory of a Member State and which reflects population exposure. It is used to calculate the national exposure reduction target and the exposure concentration obligation;

…

1. “urban background locations” shall mean places in urban areas where levels are representative of the exposure of the general urban population;

2. “oxides of nitrogen” shall mean the sum of the volume mixing ratio (ppbv) of nitrogen monoxide (nitric oxide) and nitrogen dioxide expressed in units of mass concentration of nitrogen dioxide (μg/m³);

3. “fixed measurements” shall mean measurements taken at fixed sites, either continuously or by random sampling, to determine the levels in accordance with the relevant data quality objectives;

…’

6 Article 4 of Directive 2008/50 provides:

‘Member States shall establish zones and agglomerations throughout their territory. Air quality assessment and air quality management shall be carried out in all zones and agglomerations.’

7 Under Article 5(1) of the directive:

‘The upper and lower assessment thresholds specified in Section A of Annex II shall apply to sulphur dioxide, nitrogen dioxide and oxides of nitrogen, particulate matter (PM10 and PM2,5), lead, benzene and carbon monoxide.

Each zone and agglomeration shall be classified in relation to those assessment thresholds.’

8 Article 6 of the directive, entitled ‘Assessment criteria’, is worded as follows:

‘1.

Member States shall assess ambient air quality with respect to the pollutants referred to in Article 5 in all their zones and agglomerations, in accordance with the criteria laid down in paragraphs 2, 3 and 4 of this Article and in accordance with the criteria laid down in Annex III.

2.

In all zones and agglomerations where the level of pollutants referred to in paragraph 1 exceeds the upper assessment threshold established for those pollutants, fixed measurements shall be used to assess the ambient air quality. Those fixed measurements may be supplemented by modelling techniques and/or indicative measurements to provide adequate information on the spatial distribution of the ambient air quality.

3.

In all zones and agglomerations where the level of pollutants referred to in paragraph 1 is below the upper assessment threshold established for those pollutants, a combination of fixed measurements and modelling techniques and/or indicative measurements may be used to assess the ambient air quality.

4.

In all zones and agglomerations where the level of pollutants referred to in paragraph 1 is below the lower assessment threshold established for those pollutants, modelling techniques or objective-estimation techniques or both shall be sufficient for the assessment of the ambient air quality.

…’

9 Article 7 of the same directive, headed ‘Sampling points’, provides:

‘1.

The location of sampling points for the measurement of sulphur dioxide, nitrogen dioxide and oxides of nitrogen, particulate matter (PM10, PM2,5), lead, benzene and carbon monoxide in ambient air shall be determined using the criteria listed in Annex III.

2.

In each zone or agglomeration where fixed measurements are the sole source of information for assessing air quality, the number of sampling points for each relevant pollutant shall not be less than the minimum number of sampling points specified in Section A of Annex V.

3.

For zones and agglomerations within which information from fixed measurement sampling points is supplemented by information from modelling and/or indicative measurement, the total number of sampling points specified in Section A of Annex V may be reduced by up to 50%, provided that the following conditions are met:

1. the supplementary methods provide sufficient information for the assessment of air quality with regard to limit values or alert thresholds, as well as adequate information for the public;

2. the number of sampling points to be installed and the spatial resolution of other techniques are sufficient for the concentration of the relevant pollutant to be established in accordance with the data quality objectives specified in Section A of Annex I and enable assessment results to meet the criteria specified in Section B of Annex I.

The results of modelling and/or indicative measurement shall be taken into account for the assessment of air quality with respect to the limit values.

4.

The application in Member States of the criteria for selecting sampling points shall be monitored by the Commission so as to facilitate the harmonised application of those criteria throughout the European Union.’

10 Article 13 of Directive 2008/50, entitled ‘Limit values and alert thresholds for the protection of human health’, provides in paragraph 1:

‘Member States shall ensure that, throughout their zones and agglomerations, levels of sulphur dioxide, PM10, lead, and carbon monoxide in ambient air do not exceed the limit values laid down in Annex XI.

In respect of nitrogen dioxide and benzene, the limit values specified in Annex XI may not be exceeded from the dates specified therein.

Compliance with these requirements shall be assessed in accordance with Annex III.

…’

11 Article 15 of that directive provides:

‘…

2.

Member States shall ensure that the average exposure indicator for the year 2015 established in accordance with Section A of Annex XIV does not exceed the exposure concentration obligation laid down in Section C of that Annex.

…

4.

Each Member State shall, in accordance with Annex III, ensure that the distribution and the number of sampling points on which the average exposure indicator for PM2,5 is based reflect the general population exposure adequately. The number of sampling points shall be no less than that determined by application of Section B of Annex V.’

12 Article 23(1) of Directive 2008/50 states:

‘Where, in given zones or agglomerations, the levels of pollutants in ambient air exceed any limit value or target value, plus any relevant margin of tolerance in each case, Member States shall ensure that air quality plans are established for those zones and agglomerations in order to achieve the related limit value or target value specified in Annexes XI and XIV.

In the event of exceedances of those limit values for which the attainment deadline is already expired, the air quality plans shall set out appropriate measures, so that the exceedance period can be kept as short as possible. The air quality plans may additionally include specific measures aiming at the protection of sensitive population groups, including children.

Those air quality plans shall incorporate at least the information listed in Section A of Annex XV and may include measures pursuant to Article 24. Those plans shall be communicated to the Commission without delay, but no later than 2 years after the end of the year the first exceedance was observed.

…’

13 Annex III to Directive 2008/50 deals with the ‘assessment of ambient air quality and location of sampling points for the measurement of sulphur dioxide, nitrogen dioxide and oxides of nitrogen, particulate matter (PM10 and PM2,5), lead, benzene and carbon monoxide in ambient air’. Section A thereof, entitled ‘General’, provides in paragraph 1:

‘Ambient air quality shall be assessed in all zones and agglomerations in accordance with the following criteria:

1. Ambient air quality shall be assessed at all locations except those listed in paragraph 2, in accordance with the criteria established by Sections B and C for the location of sampling points for fixed measurement. The principles established by Sections B and C shall also apply in so far as they are relevant in identifying the specific locations in which concentration of the relevant pollutants are established where ambient air quality is assessed by indicative measurement or modelling.’

14 Annex III, Section B, of that directive, entitled ‘Macroscale siting of sampling points’, provides in paragraph 1, entitled ‘Protection of human health’:

• Sampling points directed at the protection of human health shall be sited in such a way as to provide data on the following:

  • the areas within zones and agglomerations where the highest concentrations occur to which the population is likely to be directly or indirectly exposed for a period which is significant in relation to the averaging period of the limit value(s),

  • levels in other areas within the zones and agglomerations which are representative of the exposure of the general population,

• Sampling points shall in general be sited in such a way as to avoid measuring very small micro-environments in their immediate vicinity, which means that a sampling point must be sited in such a way that the air sampled is representative of air quality for a street segment no less than 100 m length at traffic-orientated sites and at least 250 m × 250 m at industrial sites, where feasible;

• Urban background locations shall be located so that their pollution level is influenced by the integrated contribution from all sources upwind of the station. The pollution level should not be dominated by a single source unless such a situation is typical for a larger urban area. Those sampling points shall, as a general rule, be representative for several square kilometres;

…

1. Sampling points shall, where possible, also be representative of similar locations not in their immediate vicinity;

…’

15 Section C of Annex III to Directive 2008/50 provides criteria for the microscale siting of sampling points, such as the distance between the sampling probe and the ground, its location in relation to streets and junctions and other technical requirements.

16 Section D of Annex III to the directive, entitled ‘Documentation and review of site selection’, states:

‘The site-selection procedures shall be fully documented at the classification stage by such means as compass-point photographs of the surrounding area and a detailed map. Sites shall be reviewed at regular intervals with repeated documentation to ensure that selection criteria remain valid over time.’

17 Annex V to that directive lays down the ‘criteria for determining minimum numbers of sampling points for fixed measurement of concentrations of sulphur dioxide, nitrogen dioxide and oxides of nitrogen, particulate matter (PM10, PM2,5), lead, benzene and carbon monoxide in ambient air’. Section A of that annex provides, inter alia:

‘For nitrogen dioxide, particulate matter, benzene and carbon monoxide: to include at least one urban background monitoring station and one traffic-orientated station provided this does not increase the number of sampling points. For these pollutants, the total number of urban background stations and the total number of traffic oriented stations in a Member State required under Section A(1) shall not differ by more than a factor of 2. Sampling points with exceedances of the limit value for PM10 within the last 3 years shall be maintained, unless a relocation is necessary owing to special circumstances, in particular spatial development.’

18 Annex XI to the directive is entitled ‘Limit values for the protection of human health’. Section B thereof sets limit values per pollutant according to its concentration in ambient air measured in different time periods. As regards nitrogen dioxide, this annex provides, in particular:

19 Annex XV to Directive 2008/50 sets out the ‘information to be included in the local, regional or national air quality plans for improvement in ambient air quality’. Among the ‘information to be provided under Article 23 (air quality plans)’, listed in Section A of that annex, the ‘localisation of excess pollution’ is mentioned, which includes information on the region, the city and the ‘measuring station (map, geographical coordinates)’. In addition, among the general information to be provided is an ‘estimate of the polluted area (km²) and of the population exposed to the pollution’.

The dispute in the main proceedings and the questions referred for a preliminary ruling

20 It is apparent from the order for reference that the Brussels Capital Region is a zone subject to air quality assessment and air quality management within the meaning of Article 4 of Directive 2008/50. Air quality is monitored using sampling points. According to the Nederlandstalige rechtbank van eerste aanleg Brussel (Dutch-language Court of First Instance, Brussels, Belgium), the latter must be located, in accordance with Article 7(1) of Directive 2008/50, read in conjunction with Annex III, Section B, paragraph 1(a) thereto, in such a way as to provide, inter alia, data on ‘the areas within zones and agglomerations where the highest concentrations’ of the pollutants covered by that directive ‘occur’.

21 Among the applicants in the main proceedings are four inhabitants of the Brussels Capital Region who are concerned about the quality of the air in their environment. The fifth applicant in the main proceedings is a non-profit-making association governed by English law with a centre of activities in Belgium. One of the objects of that association is to protect the environment.

22 By their action, brought on 21 September 2016, the applicants in the main proceedings asked the referring court to declare that the abovementioned requirement was not complied with in the Brussels Capital Region and to order the latter to establish sampling points at appropriate locations, such as a specific street or junction.

23 The referring court considers that the rules laid down in Directive 2008/50 on the identification or delimitation of ‘areas within zones and agglomerations where the highest concentrations’ of pollutants ‘occur’ confer a margin of discretion on the competent authorities. Consequently, it is not certain whether a court may verify that the sampling points have been correctly located and, if necessary, order those authorities to establish such points in areas that the court itself would determine.

24 The applicants in the main proceedings consider, for their part, that the limit value laid down in Directive 2008/50 for nitrogen dioxide since 1 January 2010 has actually been exceeded in the Brussels Capital Region. For this reason, an air quality plan, as provided for in Article 23 of that directive, should be drawn up by the competent authorities.

25 According to the referring court, if the limit values laid down in Directive 2008/50 are exceeded, the Member States are required to draw up, in accordance with Article 23(1) of that directive, an air quality plan which provides for appropriate measures to ensure that the period in which those values are exceeded is as short as possible. As is apparent from the judgment of 19 November 2014, ClientEarth (C‑404/13, EU:C:2014:2382 ), compliance with that obligation may be subject to judicial review and the court seised has the power to order the competent authorities to draw up such a plan.

26 That court also notes that the parties to the main proceedings do not dispute the values measured at the various sampling points located in the Brussels Capital Region. On the other hand, they disagree on the interpretation of Article 13(1) of Directive 2008/50, from which it follows that the concentration of nitrogen dioxide in the air must not exceed an annual average of 40 μg/m³‘throughout … zones and agglomerations’ of a Member State.

27 The wording of that provision does not make it possible to decide whether, in the Brussels Capital Region, that level was in fact exceeded. It is true that the value of 40 μg/m³ of nitrogen dioxide was exceeded at various sampling points. However, the nitrogen dioxide concentration would remain below the annual average of 40 μg/m³ if it were determined solely on the basis of the average of the values measured at all sampling points located in that region.

28 The applicants in the main proceedings consider that it follows from the wording of Article 13(1) of Directive 2008/50 that the limit values may not be exceeded in any area of a zone, within the meaning of Article 4 of the directive. On the other hand, the Brussels Capital Region and the Brussels Institute for Environmental Management consider that the air quality should be assessed for a zone or agglomeration as a whole.

29 In those circumstances, the Nederlandstalige rechtbank van eerste aanleg Brussel (Dutch-language Court of First Instance, Brussels) decided to stay the proceedings and to refer the following questions to the Court for a preliminary ruling:

• Should Article 4(3) and the second subparagraph of Article 19(1) [TEU], read in conjunction with the third paragraph of Article 288 [TFEU], and Articles 6 and 7 of Directive [2008/50] be interpreted as meaning that, when it is alleged that a Member State has not sited the sampling points in a zone in accordance with the criteria set out in paragraph 1(a) of Section B of Annex III to Directive 2008/50, it is for the national courts, on application by individuals who are directly affected by the exceedance of the limit values referred to in Article 13(1) of that directive, to examine whether the sampling points were established in accordance with those criteria and, if they were not, to take all necessary measures in respect of the national authority, such as an order, with a view to ensuring that the sampling points are sited in accordance with those criteria?

• Is a limit value within the meaning of Article 13(1) and Article 23(1) of Directive [2008/50] exceeded in the case where an exceedance of a limit value with an averaging period of one calendar year, as laid down in Annex XI to that directive, has been established on the basis of the measurement results from one single sampling point within the meaning of Article 7 of that directive, or does such an exceedance occur only when this becomes apparent from the average of the measurement results from all sampling points in a particular zone within the meaning of Directive 2008/50?’

Consideration of the questions referred

Costs

69 Since these proceedings are, for the parties to the main proceedings, a step in the action pending before the national court, the decision on costs is a matter for that court. Costs incurred in submitting observations to the Court, other than the costs of those parties, are not recoverable.