CELEX: 62021CJ0375
Reference for a preliminary ruling
Environment
Ambient air quality
Directive 2008/50/EC
Articles 13 and 23
Limit values for the protection of human health
Exceedance
Air quality plan
Directive 2010/75/EU
Integrated pollution prevention and control
Update of a permit to operate a power plant
Emission limit values
Article 15(4)
Application for a derogation setting less strict emission limit values
Significant pollution
Article 18
Compliance with environmental quality standards
Obligations of the competent authority

This request for a preliminary ruling concerns the interpretation of Article 4(3) TEU, of Articles 13 and 23 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) and of Article 15(4) and Article 18 of Directive 2010/75/EU of the European Parliament and of the Council of 24 November 2010 on industrial emissions (integrated pollution prevention and control) (OJ 2010 L 334, p. 17).
The request has been made in proceedings between Sdruzhenie ‘Za Zemyata – dostap do pravosadie’, a Bulgarian association, ‘The Green Tank – grazhdansko sdruzhenie s nestopanska tsel’ – Hellenic Republic, a Greek non-profit civil association, and NS, a Greek national, and the Executive Director of the Izpalnitelna agentsya po okolna sreda (Executive Agency for the Environment, Bulgaria) (‘the Executive Director’) and ‘TETS Maritsa iztok 2’ EAD, an operator of a thermal power plant, relating to the update by the Executive Director of the permit concerning TETS Maritsa iztok 2, a Bulgarian thermal power plant, and regarding the operation of a combustion plant for the production of electricity, a plant for the production of hydrogen and a landfill for inert waste, construction waste and hazardous and non-hazardous waste.

Legal context

European Union law

Directive 2008/50
Recital 18 of Directive 2008/50 states:
‘Air quality plans should be developed for zones and agglomerations within which concentrations of pollutants in ambient air exceed the relevant air quality target values or limit values, plus any temporary margins of tolerance, where applicable. Air pollutants are emitted from many different sources and activities. To ensure coherence between different policies, such air quality plans should where feasible be consistent, and integrated with plans and programmes prepared pursuant to Directive 2001/80/EC of the European Parliament and of the Council of 23 October 2001 on the limitation of emissions of certain pollutants into the air from large combustion plants [(OJ 2001 L 309, p. 1)], Directive 2001/81/EC [of the European Parliament and of the Council of 23 October 2001 on national emission ceilings for certain atmospheric pollutants (OJ 2001 L 309, p. 22)] and Directive 2002/49/EC of the European Parliament and of the Council of 25 June 2002 relating to the assessment and management of environmental noise [(OJ 2002 L 189, p. 12)]. Full account will also be taken of the ambient air quality objectives provided for in this Directive, where permits are granted for industrial activities pursuant to Directive 2008/1/EC of the European Parliament and of the Council of 15 January 2008 concerning integrated pollution prevention and control [(OJ 2008 L 24, p. 8)].’
Article 1 of Directive 2008/50, entitled ‘Subject matter’, 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;
…’
Article 2 of the directive, entitled ‘Definitions’, provides:
‘For the purposes of this Directive:
…
(5)      “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;
…
(9)      “target value” shall mean a level fixed with the aim of avoiding, preventing or reducing harmful effects on human health and/or the environment as a whole, to be attained where possible over a given period;
…’
Article 13 of Directive 2008/50, headed ‘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 [(SO2)], 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.
The margins of tolerance laid down in Annex XI shall apply in accordance with Article 22(3) and Article 23(1).’
Article 23 of that directive, entitled ‘Air quality plans’, provides, 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. …
…’

Directive 2010/75
Article 3 of Directive 2010/75, entitled ‘Definitions’, provides:
‘For the purposes of this Directive the following definitions shall apply:
…
(2)      “pollution” means the direct or indirect introduction, as a result of human activity, of substances, vibrations, heat or noise into air, water or land which may be harmful to human health or the quality of the environment, result in damage to material property, or impair or interfere with amenities and other legitimate uses of the environment;
…
(6)      “environmental quality standard” means the set of requirements which must be fulfilled at a given time by a given environment or particular part thereof, as set out in Union law;
…’
Article 14 of the directive, entitled ‘Permit conditions’, is worded as follows:
‘1.      Member States shall ensure that the permit includes all measures necessary for compliance with the requirements of Articles 11 and 18.
…
2.      For the purpose of paragraph 1(a), emission limit values may be supplemented or replaced by equivalent parameters or technical measures ensuring an equivalent level of environmental protection.
…
4.      Without prejudice to Article 18, the competent authority may set stricter permit conditions than those achievable by the use of the best available techniques [(BAT)] as described in the BAT conclusions. Member States may establish rules under which the competent authority may set such stricter conditions.
…’
Under Article 15 of that directive, headed ‘Emission limit values, equivalent parameters and technical measures’:
‘1.      The emission limit values for polluting substances shall apply at the point where the emissions leave the installation, and any dilution prior to that point shall be disregarded when determining those values.
…
2.      Without prejudice to Article 18, the emission limit values and the equivalent parameters and technical measures referred to in Article 14(1) and  (2) shall be based on the [BAT], without prescribing the use of any technique or specific technology.
3.      The competent authority shall set emission limit values that ensure that, under normal operating conditions, emissions do not exceed the emission levels associated with the [BAT] as laid down in the decisions on BAT conclusions referred to in Article 13(5) through either of the following:
(a)      setting emission limit values that do not exceed the emission levels associated with the [BAT]. Those emission limit values shall be expressed for the same or shorter periods of time and under the same reference conditions as those emission levels associated with the [BAT]; or
(b)      setting different emission limit values than those referred to under point (a) in terms of values, periods of time and reference conditions.
Where point (b) is applied, the competent authority shall, at least annually, assess the results of emission monitoring in order to ensure that emissions under normal operating conditions have not exceeded the emission levels associated with the [BAT].
4.      By way of derogation from paragraph 3, and without prejudice to Article 18, the competent authority may, in specific cases, set less strict emission limit values. Such a derogation may apply only where an assessment shows that the achievement of emission levels associated with the [BAT] as described in BAT conclusions would lead to disproportionately higher costs compared to the environmental benefits due to:
(a)      the geographical location or the local environmental conditions of the installation concerned; or
(b)      the technical characteristics of the installation concerned.
The competent authority shall document in an annex to the permit conditions the reasons for the application of the first subparagraph including the result of the assessment and the justification for the conditions imposed.
The emission limit values set in accordance with the first subparagraph shall, however, not exceed the emission limit values set out in the Annexes to this Directive, where applicable.
The competent authority shall in any case ensure that no significant pollution is caused and that a high level of protection of the environment as a whole is achieved.
…
The competent authority shall re-assess the application of the first subparagraph as part of each reconsideration of the permit conditions pursuant to Article 21.
…’
Article 18 of the directive, entitled ‘Environmental quality standards’, is worded as follows:
‘Where an environmental quality standard requires stricter conditions than those achievable by the use of the [BAT], additional measures shall be included in the permit, without prejudice to other measures which may be taken to comply with environmental quality standards.’
Article 31 of Directive 2010/75, entitled ‘Desulphurisation rate’, provides:
‘1.      For combustion plants firing indigenous solid fuel, which cannot comply with the emission limit values for sulphur dioxide referred to in Article 30(2) and  (3) due to the characteristics of this fuel, Member States may apply instead the minimum rates of desulphurisation set out in Part 5 of Annex V, in accordance with the compliance rules set out in Part 6 of that Annex and with prior validation by the competent authority of the technical report referred to in Article 72(4)(a).
2.      For combustion plants firing indigenous solid fuel, which co-incinerate waste, and which cannot comply with the Cproc values for sulphur dioxide set out in points 3.1 or 3.2 of Part 4 of Annex VI due to the characteristics of the indigenous solid fuel, Member States may apply instead the minimum rates of desulphurisation set out in Part 5 of Annex V, in accordance with the compliance rules set out in Part 6 of that Annex. If Member States choose to apply this paragraph, Cwaste as referred to in point 1 of Part 4 of Annex VI shall be equal to 0 mg/Nm3.
3.      The Commission shall, by 31 December 2019, review the possibility of applying minimum rates of desulphurisation set out in Part 5 of Annex V, taking into account, in particular, the [BAT] and benefits obtained from reduced sulphur dioxide emissions.’

Commission Implementing Decision (EU) 2017/1442
Commission Implementing Decision (EU) 2017/1442 of 31 July 2017 establishing best available techniques (BAT) conclusions, under Directive 2010/75/EU of the European Parliament and of the Council, for large combustion plants (OJ 2017 L 212, p. 1), imposes, inter alia, the levels of emissions associated with those BAT regarding sulphur dioxide emissions.

Bulgarian law

Law on clean ambient air
Article 6(1) of the Zakon za chistotata na atmosferniya vazduh (Law on clean ambient air) of 28 May 1996 (DV No 45 of 28 May 1996), in the version applicable to the main proceedings (‘the Law on clean ambient air’), provides:
‘(1)      the Minister for the Environment and Water and the Minister for Health shall adopt common decrees laying down limit levels for harmful substances (pollutants) in ambient air and limit levels for the deposition of harmful substances (pollutants)’.
Article 9 of Section I of the Law on clean ambient air, headed ‘Emissions from stationary sources’, in Chapter 3 thereof, headed ‘Limitation of emissions’, is worded as follows:
‘(1)      the Minister for the Environment and Water and the relevant ministers concerned shall adopt common decrees laying down limit values for the emission of harmful substances (pollutants) in ambient air by installations and activities with stationary  emission sources.
(2)      Emission limit values shall be laid down for the purpose of ensuring ambient air quality corresponding to the limit levels of harmful substances (pollutants) referred to in Article 6.
(3)      The emission limit values shall be binding in respect of all installations and activities, except in the situations referred to in Article 3(2) and Article 10a.
(4)      Emission limit values shall be drawn up on the basis of:
1.      [BAT] conclusions adopted by decision of the European Commission within the meaning of paragraph 42c of the additional provisions of the Zakon za opazvane na okolnata sreda (Law on environmental protection) (DV No 91 of 25 September 2002), in the version applicable to the main proceedings (‘the Law on environmental protection’)];
2.      the most recent technical and technological developments, scientific discoveries and results of the practical use of those discoveries.
(5)      On the basis of the conditions in a given municipality, it is possible to set emission limit values for installations and activities in given municipalities, districts and agglomerations that are stricter than those set in the decrees referred to in paragraph 1 and Articles 9a to 9d.
…’
Article 27 of the Law on clean ambient air provides:
‘(1)      Where, in a given district, the total amount of the emissions leads to exceedance of the standards for harmful substances (pollutants) in the ambient air and standards for depositions, municipal mayors shall develop and implement plans to reduce pollutant levels and comply with the established standards within the meaning of Article 6. The plans shall be adopted by municipal councils.
…
(4)      The plans referred to in paragraph 1 shall also include: objectives, measures, stages and time limits within which they must be achieved; the organisations and institutions responsible for their implementation, the means by which such implementation is to be ensured, the system by which implementation is to be reported on and reviewed, and the system for assessing the results.
(5)      Where levels of one or more pollutants exceed established standards and where the time limit for complying with those standards has passed, the plans referred to in paragraph 1 shall contain appropriate measures to ensure that the period of exceedance is kept as short as possible.
(6)      The achievement of the measures of the plans referred to in paragraph 1 must lead each year to a reduction in the number of times that the standards for harmful substances and average annual levels of pollutants are exceeded, where they are higher than the standards set for ambient air quality registered at checkpoints, which are part of the national system for monitoring the environment within the municipality.
…’

Law on environmental protection
Article 123 of the Law on environmental protection provides:
‘(1)      An integrated permit within the meaning of Article 117  shall include:
1.      …  The emission limit values of the substances in Annex 8 and of other polluting substances capable of being emitted in significant amounts by the installation concerned:
(a)      when defining emission limit values, the properties of the substances and their potential to transfer pollution from one environment to another shall be taken into consideration;
(b)      emission limit values may be supplemented or replaced by equivalent parameters or technical measures ensuring an equivalent level of environmental protection.
…
4.      the corresponding conditions for the monitoring of emissions;
…
(2)      the competent authority within the meaning of Article 120(1) shall define the permit conditions, taking into consideration the BAT conclusions.
…
(11)      … In the integrated permit, the competent authority within the meaning of Article 120(1) shall provide, if need be, additional measures for compliance with environmental quality standards that are stricter than those which may be achieved by applying the BAT. This is without prejudice to the effect of measures provided for in order to achieve compliance with other environmental quality standards. …’
Article 123a of the Law on environmental protection provides:
‘… (1)            The emission limit values referred to in Article 123(1)(1) in normal operating conditions:
1.      shall not exceed the emission levels set in the BAT conclusions established by decision of the European Commission; those emission limit values shall cover identical or shorter periods under the same reference conditions to the emission levels set in the decisions; or
2.      are different from the levels referred to in paragraph 1 but shall ensure compliance with the emission levels set in the BAT conclusions established by decision of the European Commission.
(2)      Compliance within the meaning of paragraph 1(2) shall be ensured by monitoring of emissions and assessment of the results by the supervisory authority at least once per year.
(3)      … The competent authority within the meaning of Article 120(1) may set emission limit values that are less strict than those referred to in paragraph 1 where an assessment shows that achieving the emission levels associated with the BAT, in accordance with the information in the BAT conclusions adopted by decision of the European Commission, would lead to disproportionately higher costs compared to the environmental benefits, due to:
1.      the geographical situation of the installation, or
2.      the environmental characteristics of the site, or
3.      the technical characteristics of the installation.
(4)      In the situations referred to in paragraph 3, the emission limit values must not lead to significant pollution of the environment and must make it possible to achieve a high level of protection of the environment.’
The additional provisions of the Law on environmental protection define the concepts of ‘emission limit value’, ‘environmental quality standards’, ‘integrated permit’ and ‘BAT’.

The regulation on the conditions and procedures for issuing integrated permits
Article 2 of the Naredba za usloviyata i reda za izdavane na kompleksni razreshitelni

(regulation on the conditions and procedures for issuing integrated permits) of 2 October 2009 (DV No 80 of 9 October 2009), in the version applicable to the main proceedings, sets out the conditions for issuing integrated permits.

The regulation on emission limit values for sulphur dioxide, nitrogen oxides and dust released into the atmosphere by large combustion plants
Article 12 of the Naredba za normite za dopustimi emisii na seren dioksid, azotni oksidi i prah, izpuskani v atmosferata ot golemi gorivni instalatsii (regulation on emission limit values for sulphur dioxide, nitrogen oxides and dust released into the atmosphere by large combustion plants) of 28 December 2012 (DV No 2 of 8 January 2013), in the version applicable to the main proceedings, provides:
‘(1)      Where, in a combustion plant, an indigenous solid fuel is fired which, on account of its characteristics, does not make it possible to comply with the emission limit value of sulphur dioxide defined in Article 5, it is possible to apply the minimum desulphurisation rates defined in Part 5 of Annex No 1, in accordance with the rules laid down in Part 6 of Annex No 1.
(2)      The application of the derogation provided for in paragraph 1 may be authorised on the basis of a technical justification for the impossibility of complying with the emission limit values defined in Article 5, submitted by the operator before the integrated permit is granted/reviewed and approved by the Minister for the Environment and Water or by an official appointed by the Minister.
(3)      For the purposes of the annual report made to the European Commission, operators of combustion plants shall submit to the Minister for the Environment and Water, before 31 March, information concerning the preceding year relating to:
1.      the sulphur content of the fuel used and the desulphurisation rate achieved, in average monthly values per chimney or per boiler, for the installations to which paragraph 1 applies …’

The dispute in the main proceedings and the questions referred for a preliminary ruling
TETS Maritsa iztok 2 is the largest of four thermal power plants situated within the energy complex of Maritsa iztok in Bulgaria, with a total installed capacity of 1 602 megawatts (MW). It was built in the territory of the municipality of Radnevo (Bulgaria), approximately 24.5 km as the crow flies from the municipality of Galabovo (Bulgaria), and is composed of eight generating units with built-in desulphurisation units.
By his decision of 21 December 2018, the Executive Director updated the integrated permit issued to TETS Maritsa iztok 2 in 2005 for the operation of the installations referred to above (‘the decision at issue’). The decision was taken on the basis of the Law on environmental protection adopted for the purposes of transposing Directive 2010/75, read in conjunction with Implementing Decision 2017/1442.
The Executive Director considered that the emission limit values of sulphur dioxide (SO2) and mercury could be replaced by equivalent parameters or technical measures ensuring an equivalent level of environmental protection. Regarding SO2, he thus granted a derogation, establishing a desulphurisation rate under Article 123(1)(1)(b) of the Law on environmental protection, read in conjunction with Article 12 of the regulation of 28 December 2012, in the version applicable to the main proceedings, and Article 31 of Directive 2010/75.
However, the desulphurisation rate thus authorised was established pursuant to Article 123a(3) of the Law on environmental protection, by way of derogation, at 97% and 97.5%. Those desulphurisation levels which cannot, in fact, guarantee a maximum emission level associated with the BAT of 320 mg/Nm
for SO2 usually required, but which are such as to result in SO2 emissions of 570 mg/Nm
, were thus established in so far as a higher desulphurisation level would have required significant investments on the part of the operator concerned and therefore a rise in costs that was considered disproportionate within the meaning of that provision.
The action brought by Sdruzhenie ‘Za Zemyata – dostap do pravosadie’ against the decision at issue was rejected by judgment of the Administrativen sad Stara Zagora (Administrative Court, Stara Zagora, Bulgaria) of 28 August 2020.
That court held that, contrary to the arguments made by Sdruzhenie ‘Za Zemyata – dostap do pravosadie’, there was no need to examine and assess the significance of the update of the plan for the  management of ambient air quality in the municipality of Galabovo, developed for the pollutants: particulate matter (PM10) and sulphur dioxide (SO2) for 2019-2023, adopted by the municipal council of Galabovo on 30 November 2018 pursuant to Article 23 of Directive 2008/50.  That court considered that the detailed procedure for the issue and updating of integrated permits defined in the regulation of 2 October 2009, in the version applicable to the main proceedings, did not require such a plan to be developed as a precondition for updating an integrated permit, with the result that the Executive Directive was not required to comply with the content of that plan.
As a result, that court held that, in accordance with Article 123(1)(b) of the Law on environmental protection, admissible emission standards could be supplemented or replaced by equivalent parameters or technical measures ensuring an equivalent level of environmental protection. It also held, referring, inter alia, in that connection, to Article 15(4) of Directive 2010/75, the provisions of which were transposed in  Article 123a(3) and (4) of that law, that the derogation on the reduction in the desulphurisation rate required in order to achieve the SO2 emission values usually applicable could have validly been granted on the basis of those provisions and of Article 31 of that directive.
Sdruzhenie ‘Za Zemyata – dostap do pravosadie’, ‘The Green Tank – grazhdansko sdruzhenie s nestopanska tsel’ – Hellenic Republic and NS brought an appeal on a point of law before the referring court.
That court points out, inter alia, that the plan of the municipality of Galabovo referred to in paragraph 27 of the present judgment contains a long-term measure for the reduction of SO2 pollution entitled ‘Implementation of projects for the conversion of desulphurisation plants and achievement of a minimum desulphurisation level of 98% and prohibition of the operation of boiler units without functioning desulphurisation plants’. It observes, in that regard, that the reduced desulphurisation rates authorised by the Executive Director in the decision at issue are not consistent with that minimum desulphurisation rate of 98%.
That court also states that it is established that, in the municipality of Galabovo, the authorised daily and hourly average rates of SO2 are systematically exceeded, which led, inter alia, to the adoption and update of the plan referred to above and gave rise to the bringing of an action for failure to fulfil obligations in Case C‑730/19,
Commission
v
Bulgaria
, pending before the Court.
Moreover, it is apparent from that plan that, in that municipality, hourly average concentrations of SO2 originate from various other industrial and domestic sources, the interaction of which thus contributes, inter alia, to the exceedances referred to above.
The question thus arises as to what extent the Executive Director could have been required, at the time of the adoption of the decision at issue, to take account of the various factors referred to in paragraphs 30 to 32 of the present judgment.
In those circumstances, the Varhoven administrativen sad (Supreme Administrative Court) decided to stay the proceedings and to refer the following questions to the Court of Justice for a preliminary ruling:
‘(1)      Is Article 4(3) TEU, read in conjunction with Article 18 of Directive [2010/75] and Articles 13 and 23 of Directive [2008/50], to be interpreted as meaning that, when considering a request for a derogation under Article 15(4) of Directive [2010/75], the competent authority must assess whether the granting of the derogation may jeopardise compliance with the environmental quality standards, taking into account all the relevant scientific data on pollution, including the measures under the relevant air quality programme in a given zone or agglomeration pursuant to Article 23 of Directive [2008/50]?
(2)      Is Article 4(3) TEU, read in conjunction with Article 18 of Directive [2010/75] and Articles 13 and 23 of Directive [2008/50], to be interpreted as meaning that, when considering a request for a derogation within the meaning of Article 15(4) of Directive [2010/75], the competent authority must refrain from setting less stringent emission limit values for air pollutants from an installation in so far as such a derogation would be contrary to the measures laid down in the relevant air quality programme adopted in the given zone or agglomeration pursuant to Article 23 of Directive [2008/50] and could jeopardise achieving the objective of keeping the period of exceedance of the air quality standards as short as possible?
(3)      Is Article 4(3) TEU, read in conjunction with Article 18 of Directive [2010/75] and Article 13 of Directive [2008/50], to be interpreted as meaning that, when considering a request for a derogation under Article 15(4) of Directive [2010/75], the competent authority must assess whether, taking into account all the relevant scientific data on pollution, including the cumulative effect together with other sources of the pollutant concerned, the setting of less stringent emission limit values for air pollutants from an installation would contribute to the exceedance of the relevant emission limit values set in a given zone or agglomeration in accordance with Article 13 of Directive [2008/50], and, if so, whether it must refrain from granting a derogation which would jeopardise the attainment of the environmental quality standards?’

Consideration of the questions referred
As a preliminary point, it must be noted, first, that, even though the questions referred to the Court relate, inter alia, to Article 4(3) TEU, the grounds of the order for reference do not explain why it is necessary to interpret that provision of the  TEU for the purposes of the decision which the referring court is required to make in the main proceedings; the conclusion of that order for reference, preceding the wording of those questions, itself refers, moreover, to the need to refer questions to the Court regarding the interpretation of only the relevant provisions of Directives 2008/50 and 2010/75.
In those circumstances, there does not appear to be any need to address the interpretation of Article 4(3) TEU in order to answer the questions raised by the referring court in the present case.
Having regard to the foregoing, it must be considered that, by the questions referred, which it is appropriate to examine together, the referring court asks, in essence, whether Article 15(4) of Directive 2010/75, read in conjunction with Article 18 thereof and with Articles 13 and 23 of Directive 2008/50, must be interpreted as meaning that, when considering a request for a derogation under Article 15(4), the competent authority must, taking into account all the relevant scientific data on pollution including the cumulative effect with other sources of the pollutant concerned and the measures under the relevant air quality plan established for a given zone or agglomeration in accordance with  Article 23 of Directive 2008/50, refrain from granting such a derogation when that derogation is capable of contributing to exceedance of the air quality standards defined pursuant to Article 13 of Directive 2008/50 or being contrary to the measures included in the plan intended to ensure compliance with those standards and to keep the period of exceedance thereof as short as possible.
Regarding Directive 2008/50, it must be borne in mind that, under Article 1(1) thereof, the directive lays down measures aimed at 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. In that context, the first subparagraph of Article 13(1) of that directive provides that the Member States must ensure that, throughout their zones and agglomerations, levels of SO2, in particular, in ambient air do not exceed the limit values laid down in Annex XI to that directive (judgment of 12 May 2022,
Commission
v
Bulgaria (Limit values – SO2)
, C‑730/19, not published, EU:C:2022:382, paragraph 62).
Moreover, the Court has observed that Article 23 of Directive 2008/50 establishes a direct link between, first, the exceedance of the limit values for SO2, as laid down in the provisions of Article 13(1) of, in conjunction with Annex XI to, the directive, and, secondly, the establishment of air quality plans (judgment of 12 May 2022,
Commission
v
Bulgaria (Limit values – SO2)
, C‑730/19, not published, EU:C:2022:382, paragraph 129 and the case-law cited). It is apparent from the first subparagraph of Article 23(1) of Directive 2008/50 that a finding of such exceedance in a given zone or agglomeration must lead to the adoption of such a plan.
Regarding the establishment of those plans, the Court has also specified that it follows from the second subparagraph of Article 23(1) of Directive 2008/50 that, while Member States have a degree of discretion in deciding which measures to adopt, those measures must, in any event, ensure that the period during which the limit values for the pollutant concerned are exceeded is kept as short as possible (judgment of 12 May 2022,
Commission
v
Bulgaria (Limit values – SO2)
, C‑730/19, not published, EU:C:2022:382, paragraph 132 and the case-law cited).
However, in the present case, it must be noted that the Court has recently held that, since 2007 in Zone BG0006 (south-east Bulgaria), where the municipality of Galabovo and TETS Maritsa  iztok 2 are situated, the Republic of Bulgaria had failed to fulfil its obligations under Articles 13 and 23 of Directive 2008/50 on account of the exceedance of air quality limit values for SO2 and the insufficiency of the air quality plans (judgment of 12 May 2022,
Commission
v
Bulgaria (Limit values – SO2)
, C‑730/19, not published, EU:C:2022:382, paragraphs 21, 23, 29 and 149).
As for the connections that may exist between Directive 2008/50 and Directive 2010/75, it must be specified from the outset that recital 18 of Directive 2008/50 states expressly that full account must also be taken of the ambient air quality objectives provided for in the latter directive, where permits are granted for industrial activities pursuant to Directive 2008/1; that directive has since been replaced by Directive 2010/75, which recast various relevant directives applicable until that time.
Regarding Directive 2010/75, it must be borne in mind that the specific setting of emission limit values applicable to an installation such as the power plant in the main proceedings is governed by that directive, Article 15(3) thereof in particular, according to which the competent authority is to set emission limit values that ensure that, under normal operating conditions, emissions do not exceed the emission levels associated with the BAT as laid down in the decisions on BAT conclusions referred to in Article 13(5) of the directive.
By way of derogation from Article 15(3) of Directive 2010/75, Article 15(4) thereof allows the competent authority to set less strict emission limit values if achieving the emission levels associated with the BAT leads to disproportionately higher costs compared to the environmental benefits on account of the geographical situation of the installation or the technical characteristics thereof.
However, it is apparent from Article 15(4) that such derogation may be granted only where the other conditions imposed by that provision are complied with and that the possibility that it may be granted is, in addition, without prejudice to Article 18 of Directive 2010/75.
Accordingly, in the first place, it must be borne in mind that under the fourth subparagraph of Article 15(4) of Directive 2010/75, the competent authority must in any case ensure that no ‘significant pollution’ is caused by the granting of a derogation and that a ‘high level of protection of the environment’ is achieved ‘as a whole’.
The derogation in Article 15(4) of Directive 2010/75 is therefore not intended to cover all situations in which compliance with the general emission limit values entails disproportionate costs for the operator of an installation. Such a derogation may be granted only if less strict emission limit values do not cause ‘significant pollution’ and a ‘high level of protection of the environment as a whole’ is achieved despite that derogation.
Regarding, first, the condition relating to the absence of significant pollution, it must be noted that, having regard, first, to the definition of the concept of ‘pollution’ in Article 3(2) of Directive 2010/75, which covers, inter alia, the introduction of substances into the air which may be harmful to human health or the quality of the environment and, second, to the content of Directive 2008/50 which set the air quality limit values for SO2, any introduction of that substance into the air constitutes pollution for the purposes of the fourth subparagraph of Article 15(4) of Directive 2010/75.
Moreover, as is apparent from paragraph 41 of the present judgment, it is not disputed that the air quality limit values laid down by Directive 2008/50 for SO2 must be regarded as having been exceeded within the area affected by the power plant in question in the main proceedings.
As set out by the Advocate General in point 57 of her Opinion, such exceedance of the air quality limit values for SO2 cannot be regarded as insignificant pollution, but must necessarily be held to be ‘significant pollution’ for the purposes of the fourth subparagraph of Article 15(4) of Directive 2010/75, having regard to the objectives pursued by Directive 2008/50, recalled in paragraph 38 of the present judgment, and to the fact, in addition, that, regarding SO2, the EU legislature has not provided for the possibility of extending the deadline for compliance with the air quality limit values.
Regarding, second, the limitation of the granting of the derogation laid down in Article 15(4) of Directive 2010/75 by the requirement of ensuring a ‘high level of protection of the environment as a whole’, it must be stated that the rules laid down in Directive 2008/50 on ambient air quality put into concrete terms the European Union’s obligations concerning environmental protection and the protection of public health, which stem, inter alia, from Article 3(3) TEU and Article 191(1) and (2) TFEU, according to which EU policy on the environment is to aim at a high level of protection, taking into account the diversity of situations in the various regions of the European Union, and is to be based, inter alia, on the precautionary principle and on the principle that preventive action should be taken (judgment of 26 June 2019,
Craeynest and Others
, C‑723/17, EU:C:2019:533, paragraph 33 and the case-law cited).
It follows that a derogation cannot be granted on the basis of Article 15(4) of Directive 2010/75 if it is such as to contribute to the exceedance of air quality limit values set by Directive 2008/50 for SO2.
In that connection, it must also be specified that, under the precautionary principle, where uncertainties remain as to whether less strict emission limit values will lead to ‘significant pollution’ within the meaning of the fourth subparagraph of Article 15(4) of Directive 2010/75, a derogation cannot be granted (see, to that effect, judgment of 10 October 2019,
Luonnonsuojeluyhdistys Tapiola
, C‑674/17, EU:C:2019:851, paragraph 66).
In those circumstances, the granting of a derogation under Article 15(4) of Directive 2010/75 requires a comprehensive assessment taking account of all sources of pollutants and their cumulative effect, in order to ensure that even if a derogation is granted for one of the sources, the sum total of their emissions does not cause any exceedance of the air quality limit values as defined by Directive 2008/50.
In the second place, it must be borne in mind that the derogation provided for in Article 15(4) of Directive 2010/75 is without prejudice to the application of Article 18 of the directive. Article 18 provides that where an environmental quality standard requires stricter conditions than those achievable by the use of the BAT, additional measures are to be included in the permit, without prejudice to other measures which may be taken to comply with environmental quality standards.
Article 3(6) of the Directive 2010/75 defines an ‘environmental quality standard’ as the set of requirements which must be fulfilled at a given time by a given environment or particular part thereof, as set out in EU law.
According to the Court’s case-law, such standards relate to specific qualitative requirements, relating to concentrations of polluting substances, that must be met at a given time by the particular medium concerned (see, to that effect, judgment of 26 May 2011,
Stichting Natuur en Milieu and Others
, C‑165/09 to C‑167/09, EU:C:2011:348, paragraph 62).
It should also be borne in mind that, as observed in paragraph 42 of the present judgment, recital 18 of Directive 2008/50 states expressly that full account must be taken of the ambient air quality objectives provided for in that directive, where permits are granted for industrial activities such as those covered by Directive 2010/75.
Have regard to the foregoing, and as noted by the Advocate General in point 82 et seq. of her Opinion, it must be held that the air quality limit values for certain pollutants under Article 13 of and Annex XI to Directive 2008/50 constitute such ‘environmental quality standards’ within the meaning of Article 18 of Directive 2010/75.
Air quality limit values must, in principle, be complied with at all times and anywhere in the European Union (see, to that effect, judgments of 30 April 2020,
Commission
v
Romania (Exceedance of the limit values for PM10)
, C‑638/18, not published, EU:C:2020:334,  paragraphs 73 and 74, and of 10 November 2020,
Commission
v
Italy (Limit values – PM10)
, C‑644/18, EU:C:2020:895, paragraphs 96 and 97).
The fact that the definition of ‘environmental quality standards’ refers to a series of requirements that must be met only ‘at a given time’ does not preclude air quality limit values, which must be complied with at all times, from being covered by that definition. Although that definition allows for the inclusion of requirements which must not be complied with at all times,  permanent requirements certainly constitute ‘environmental quality standards’, for the purposes of that definition, because they apply at any given point in time.
Article 18 of Directive 2010/75 thus confirms the interpretation of Article 15(4) of the directive that the competent authority must assess whether the setting of less strict emission limit values for air pollutants from a given installation would contribute to the exceedance of the air quality limit values for the concentrations of such sources of pollution in the zone or agglomeration concerned in accordance with Article 13 of Directive 2008/50 and, if this should be the case, refrain from granting a derogation which would jeopardise compliance with environmental quality standards.
In the third place, it must further be specified that, where the air quality limit values are exceeded in the area affected by a given installation, such a derogation from emission limit values may be granted only where the requirements in the air quality plans are complied with, for the purposes of Article 23 of Directive 2008/50, as they have necessarily been drawn up in an exceedance context.
First, having regard to what has been recalled in paragraph 40 of the present judgment, and as observed by the Advocate General in paragraph 67 of her Opinion, although Member States are free to organise the responsibilities of their authorities by providing that the air quality plan concerned results from various measures adopted by various authorities, they must, however, satisfy themselves that those measures comply, as a whole, with the requirements of Article 23 of Directive 2008/50 and, together, achieve the objective of complying with air quality limit values.
Second, as is apparent from paragraphs 46 to 50 of the present judgment, a derogation from emission limit values cannot be granted under the fourth subparagraph of Article 15(4) of Directive 2010/75 when that derogation would be such as to contribute to ‘significant pollution’  within the meaning of that provision and, in particular, to an exceedance of SO2 air quality limit values established pursuant to Directive 2008/50. Requirements set by air quality plans are intended specifically to prevent such exceedances, by ensuring that the exceedance period is kept as short as possible.
Accordingly, the authority empowered to grant such a derogation must also refrain from setting less strict emission limit values for pollutants originating from an installation where such a derogation would be contrary to the measures established in the air quality plan adopted in the zone or agglomeration concerned in accordance with Article 23 of Directive 2008/50, in particular those requiring, as in the present case, compliance with desulphurisation rates, and would jeopardise the achievement of the objective of ensuring that the period during which the limit values are exceeded is kept as short as possible.
Having regard to all the foregoing considerations, the answer to the questions referred is that Article 15(4) of Directive 2010/75, read in conjunction with Article 18 thereof and with Articles 13 and 23 of Directive 2008/50, must be interpreted as meaning that, when considering a request for a derogation under Article 15(4) of the directive, the competent authority must, taking into account all the relevant scientific data on pollution including the cumulative effect with other sources of the pollutant concerned and the measures under the relevant air quality plan established for a given zone or agglomeration in accordance with Article 23 of Directive 2008/50, refrain from granting such a derogation when that derogation is capable of contributing to exceedance of the air quality standards defined pursuant to Article 13 of Directive 2008/50 or being contrary to the measures included in the plan intended to ensure compliance with those standards and to keep the period of exceedance thereof as short as possible.

Costs
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.
On those grounds, the Court (Second Chamber) hereby rules:
Article 15(4) of Directive 2010/75/EU of the European Parliament and of the Council of 24 November 2010 on industrial emissions (integrated pollution prevention and control), read in conjunction with Article 18 thereof and with Articles 13 and 23 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,
must be interpreted as meaning that when considering a request for a derogation under Article 15(4) of the directive, the competent authority must, taking into account all the relevant scientific data on pollution including the cumulative effect with other sources of the pollutant concerned and the measures under the relevant air quality plan established for a given zone or agglomeration in accordance with Article 23 of Directive 2008/50, refrain from granting such a derogation when that derogation is capable of contributing to exceedance of the air quality standards defined pursuant to Article 13 of Directive 2008/50 or being contrary to the measures included in the plan intended to ensure compliance with those standards and to keep the period of exceedance thereof as short as possible.
[Signatures]
*
Language of the case: Bulgarian.