1

By its application, the European Commission claims that the Court should:

2

Article 13 of 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), 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.

…’

3

Article 23 of that directive, entitled ‘Air quality plans’, states, in paragraph 1:

‘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 two years after the end of the year the first exceedance was observed.

…’

4

Article 27 of that directive, entitled ‘Transmission of information and reporting’, provides:

‘1.   Member States shall ensure that information on ambient air quality is made available to the Commission within the required timescale as determined by the implementing measures referred to in Article 28(2).

2.   In any event, for the specific purpose of assessing compliance with the limit values and critical levels and the attainment of target values, such information shall be made available to the Commission no later than nine months after the end of each year …’

5

Annex XI to the directive is entitled ‘Limit values for the protection of human health’. According to that annex, the daily limit value for PM10 not to be exceeded more than 35 times per calendar year is 50 micrograms per cubic metre (μg/m3), and the annual limit value is 40 μg/m3 per calendar year. Annex XI states that the date on which those limit values had to be met was 1 January 2005.

6

In its judgment of 5 April 2017, Commission v Bulgaria (C‑488/15, EU:C:2017:267), the Court held that:

the Republic of Bulgaria failed to fulfil its obligations under the provisions of Article 13(1) of, in conjunction with Annex XI to, Directive 2008/50.

7

Furthermore, the Court held that, in view of the fact that the daily and annual limit values for PM10 concentrations in all of the abovementioned zones and agglomerations continued to be exceeded, the Republic of Bulgaria failed to fulfil its obligations under the second subparagraph of Article 23(1) of that directive and in particular the obligation to keep the exceedance period as short as possible, as regards the period from 11 June 2010 to the year 2014 inclusive.

8

Following delivery of the judgment of 5 April 2017, Commission v Bulgaria (C‑488/15, EU:C:2017:267), the Commission requested, by letter of 11 May 2017, that the Republic of Bulgaria provide it with information on the measures taken to comply with that judgment.

9

By several letters dated between 5 June 2017 and 26 September 2018, the Republic of Bulgaria set out for the Commission the various measures taken to comply with that judgment, while stating that certain limit values for PM10 concentrations had now been complied with in several municipalities located in the zones covered by that judgment.

10

On the basis of the raw air quality data for 2015 and 2016, the Commission found that, for those years, the daily limit value for PM10 concentrations had not been complied with in any of the six zones referred to in the Court’s judgment, whereas the annual limit value for those concentrations had been exceeded in all of those zones with the exception of zone BG0003 AG Varna.

11

On 9 November 2018, the Commission then sent the Republic of Bulgaria a letter of formal notice under Article 260(1) TFEU. In that letter, it stated that, approximately a year and a half after the delivery of the judgment of 5 April 2017, Commission v Bulgaria (C‑488/15, EU:C:2017:267), and almost 11 years after the entry into force of Directive 2008/50, the Republic of Bulgaria had still not taken the measures necessary to put an end to the failures to fulfil obligations established by that judgment. Furthermore, it invited that Member State to submit its observations within a period of two months, subsequently extended by a further month until 9 February 2019 (‘the reference date’), and to inform it of any progress made in the meantime.

12

After providing an initial set of information on 8 January 2019, the Republic of Bulgaria replied, by letter of 18 January 2019, to the letter of formal notice before sending, in the form of several letters, additional information between 22 July 2019 and 1 September 2020. In those letters, it stated, inter alia, that the annual limit value had been complied with for 2017 and 2018 in the BG0005 South-West zone, while the annual limit value had not been exceeded in 2019 in the BG0005 South-West, BG0006 South-East and BG0001 AG Sofia zones. It also stated that, in certain municipalities located in those zones, compliance with the limit values for ambient air quality had been maintained, while exceedances continued to decrease in other municipalities. Next, the Republic of Bulgaria stated that it had taken various measures to limit prohibited exceedances, in particular in relation to the main sources of pollution – domestic heating and transport.

13

While provisionally excluding zone BG0003 AG Varna from the pre-litigation procedure, the Commission considered that, in the light of the information provided by the Republic of Bulgaria and the air quality reports submitted pursuant to Article 27 of Directive 2008/50 for the period from 2015 to 2019, that Member State had not taken all the measures necessary to comply with the judgment of 5 April 2017, Commission v Bulgaria (C‑488/15, EU:C:2017:267), because the annual and daily limit values had still not been complied with in the five other zones covered by that judgment and the exceedance period had not been limited to the shortest possible period in those five zones.

14

In those circumstances, the Commission decided to bring the present action.

15

By decision of the President of the Court of 18 August 2021, the Republic of Poland was granted leave to intervene in support of the form of order sought by the Republic of Bulgaria.

16

Considering that the general principles which apply to the pre-litigation procedure referred to in Article 258 TFEU must apply mutatis mutandis to that referred to in Article 260(2) TFEU and noting that, in accordance with the case-law of the Court, in order for a reasoned opinion to be issued pursuant to the first paragraph of Article 258 TFEU a prior failure on the part of the Member State concerned to fulfil an obligation owed by it must be capable of being legitimately alleged by the Commission, the Republic of Bulgaria, supported by the Republic of Poland, infers from this, in its defence, that, in order to be able to send a letter of formal notice under Article 260(2) TFEU, the Commission must allege that the Member State concerned has failed to fulfil its obligation to comply with a judgment of the Court establishing a failure to fulfil obligations.

17

The Republic of Bulgaria asserts that the Commission’s allegation in the letter of formal notice relating to the alleged failure to comply with the judgment of the Court of 5 April 2017, Commission v Bulgaria (C‑488/15, EU:C:2017:267), is based on factual circumstances which occurred before that judgment was delivered, namely data relating to ambient air quality for 2015 and 2016, with the result that, on the date of the letter of formal notice, that is, 9 November 2018, the Commission could not determine with certainty whether there had been a failure to fulfil obligations under Article 260(1) TFEU or, therefore, legitimately allege that the Republic of Bulgaria had not complied with that judgment. Accordingly, the Commission prematurely opened the pre-litigation stage of the procedure laid down in Article 260(2) TFEU, in breach of the requirements of legal certainty.

18

The Republic of Bulgaria, supported by the Republic of Poland, contends that the action is inadmissible.

19

While considering that the material subject matter of the present action for failure to fulfil obligations has been neither extended nor supplemented in the light of the judgment of 5 April 2017, Commission v Bulgaria (C‑488/15, EU:C:2017:267), the Commission recalls, in its reply, the settled case-law of the Court according to which, in the event of a systematic and persistent failure to comply with the provisions of an EU act, additional information may be produced after the reasoned opinion, while the subject matter of the action for failure to fulfil obligations may also extend to facts subsequent to that opinion.

20

The Commission also submits that the data for 2015 and 2016 undeniably show persistent exceedances of the limit values for PM10 concentrations, which the Bulgarian population had to tolerate for several years after the date referred to in the Court’s judgment. In that context, in view of the persistence of the failure to fulfil obligations, the Commission considers that it was entitled to initiate a pre-litigation procedure. Furthermore, the argument that the Commission is formally required to wait several years after the delivery of the Court’s judgment under Article 258 TFEU before ‘being entitled to seek compliance with that judgment’ is fundamentally unacceptable, since such a ‘grace period’ is not provided for either in the Treaties or by the reporting mechanism as provided for in Article 27 of Directive 2008/50, nor does it follow from the principle of legal certainty.

21

In its rejoinder, the Republic of Bulgaria states that it contends that the action is inadmissible in the light not of the substantive aspects of the action, but of the temporal factors which characterise the present case. In particular, the defect vitiating the action for failure to fulfil obligations results not from an extension of the action after the letter of formal notice, but from the initial lack of a basis for initiating the pre-litigation procedure which led to the present action. In those circumstances, the fact that the subject matter of the action concerns the failure to comply with a judgment of the Court finding a ‘persistent’ failure to fulfil obligations cannot remedy such a defect, since the pre-litigation procedure initiated under Article 260(2) TFEU must be lawful in order to guarantee the rights of the Member State concerned.

22

It should be recalled that, under Article 260(1) and (2) TFEU, a Member State in respect of which the Court has found that it has failed to fulfil an obligation under the Treaties is required to take the necessary measures to comply with the judgment of the Court, and the Commission may bring the matter before the Court if it considers, after giving the Member State concerned the opportunity to submit its observations, that such measures have not been taken.

23

That procedure has the objective of inducing a defaulting Member State to comply with a judgment establishing a breach of obligations (judgment of 12 July 2005, Commission v France, C‑304/02, EU:C:2005:444, paragraph 80). That process of compliance must be initiated immediately after the delivery of that judgment and completed as soon as possible (see, to that effect, judgments of 6 November 1985, Commission v Italy, 131/84, EU:C:1985:447, paragraph 7, and of 12 November 2019, Commission v Ireland (Derrybrien wind farm), C‑261/18, EU:C:2019:955, paragraph 123 and the case-law cited).

24

It is also apparent from the case-law of the Court that the reference date which must be used for assessing whether there has been a failure to fulfil obligations under Article 260(1) TFEU, namely a failure to fulfil the obligation to take the necessary measures to comply with the judgment of the Court, is that of the expiry of the period prescribed in the letter of formal notice issued under Article 260(2) TFEU (see, to that effect, judgment of 11 December 2012, Commission v Spain, C‑610/10, EU:C:2012:781, paragraph 67).

25

It must be held that, by analogy with the case-law relating to actions for failure to fulfil obligations based on Article 258 TFEU, in order for a letter of formal notice to be issued pursuant to Article 260(2) TFEU, if the requirements of legal certainty are not to be disregarded, a prior failure to fulfil the obligation to take the necessary measures to comply with the judgment of the Court must be capable of being legitimately alleged by the Commission (see, to that effect, judgment of 5 December 2019, Commission v Spain (Waste management plans), C‑642/18, EU:C:2019:1051, paragraphs 17, 18 and 26 and the case-law cited).

26

In view of the purpose of the procedure referred to in paragraph 23 of the present judgment, that means that the Commission is required not only to ascertain, throughout the pre-litigation procedure and before issuing the letter of formal notice, whether or not the judgment in question has been complied with in the meantime, but also to allege and establish, prima facie, with clarity, in that letter of formal notice, that the judgment remains to be complied with on the reference date.

27

A Member State cannot legitimately be accused of having failed to fulfil its obligation to take the necessary measures to comply with a judgment of the Court if it is not clear from the letter of formal notice that, on the reference date, the obligation to comply with that judgment has continued to exist since its delivery.

28

In the present case, it should be noted that, in the letter of formal notice of 9 November 2018, the Commission did not, with the requisite clarity, allege or establish, prima facie, that the judgment of 5 April 2017, Commission v Bulgaria (C‑488/15, EU:C:2017:267), still had to be complied with on the reference date, that is, 9 February 2019.

29

In that letter, the Commission states that the failures to fulfil obligations established up to 2014 in that judgment, in respect of the zones and agglomerations referred to in that letter, continued during 2015 and 2016, without providing detailed explanations or a factual analysis indicating that the situation identified during those two years continued without any significant improvement during the period between the delivery of the judgment on 5 April 2017 and the reference date, 9 February 2019, thus making it necessary to take measures to comply with that judgment.

30

Neither the fact that those failures to fulfil obligations continued between the end of the period covered by the Court’s judgment, namely 2014, and a subsequent period, which nevertheless preceded the date of delivery of the judgment, namely 2015 and 2016, nor the systematic and persistent nature of those failures to fulfil obligations established by the Court in that judgment automatically means that, both on the date of its delivery and on the reference date, that judgment still had to be complied with and that the Republic of Bulgaria could therefore be criticised for not having taken all the measures necessary to comply with it.

31

Therefore, by failing, in the letter of formal notice, to allege and establish, prima facie, with the requisite clarity, the essential prerequisite that the judgment of 5 April 2017, Commission v Bulgaria (C‑488/15, EU:C:2017:267), still had to be complied with on the reference date as regards the zones and agglomerations referred to in that letter, the Commission did not legitimately allege that the Republic of Bulgaria failed to fulfil its obligation to take the necessary measures to comply with that judgment.

32

In those circumstances, the Commission’s action for failure to fulfil obligations must be dismissed as inadmissible.

33

Under Article 138(1) of the Rules of Procedure of the Court of Justice, the unsuccessful party is to be ordered to pay the costs if they have been applied for in the successful party’s pleadings. Since the Republic of Bulgaria has applied for costs and the action brought by the Commission has been declared inadmissible, the Commission must be ordered to pay the costs.

34

Pursuant to Article 140(1) of the Rules of Procedure, which provide that Member States which have intervened in the proceedings are to bear their own costs, the Republic of Poland must be ordered to bear its own costs.

On those grounds, the Court (Third Chamber) hereby: