REPORT FROM THE COMMISSION TO THE EUROPEAN PARLIAMENT, THE COUNCIL, THE EUROPEAN ECONOMIC AND SOCIAL COMMITTEE AND THE COMMITTEE OF THE REGIONS The Fourth Clean Air Outlook
Date: 2025-03-03
Institutions: Directorate-General for Environment, European Commission
Subjects: EU emission allowance, EU environmental policy, air quality, atmospheric pollutant, environmental cooperation, environmental impact, environmental protection, pollution control, prevention of pollution, reduction of gas emissions

EN 

  EN 

   EUROPEAN COMMISSION  Brussels, 3.3.2025  COM(2025) 64 final  REPORT FROM THE COMMISSION TO THE EUROPEAN PARLIAMENT, THE COUNCIL, THE EUROPEAN ECONOMIC AND SOCIAL COMMITTEE AND THE COMMITTEE OF THE REGIONS The Fourth Clean Air Outlook  
 
 
The Fourth Clean Air Outlook 

1. 

INTRODUCTION 

Air pollution  in  the EU  has decreased over the last  decades  as  a result of  EU  clean air 
legislation and joint action taken by the EU and national, regional and local authorities. 
Emissions  of  the  five  main  air  pollutants  have  fallen  significantly  between  2005-2024. 
And  yet  air  quality  remains  a  serious  concern  for  the  health  of  European  citizens, 
especially  in  urban  areas  where  pollution  levels  remain  above  WHO  guideline  levels1, 
and for the state of ecosystems. 

The  EU’s  approach  to  improving  air  quality  involves  taking  action  in  three  areas  (or 
‘pillars’).  The  first  is  on  ambient  air  quality  standards  set  in  the  revised  Ambient  Air 
Quality  Directive2.  The  second  is  to  set  national  emission  reduction  obligations  under 
the National Emission reduction Commitments Directive (NEC Directive)3 for the main 
transboundary  air  pollutants4.  The  third  is  to  set  emission  standards  at  EU  level,  laid 
down  in  legislation,  for  key  sources  of  pollution  from  vehicle  and  ship  emissions  to 
energy  and  industry,  as  well  as  ecodesign  requirements  for  boilers  and  stoves.  Most 
emissions from agricultural activities, however, are not regulated. 

The EU has stepped up action under all three pillars to adapt to new policy and scientific 
developments.  In  particular,  to  implement  the  European  Green  Deal  and  the  EU’s 
ambition to  reach  zero pollution for a toxic-free  environment, the Ambient  Air Quality 
Directive has been revised to bring in more ambitious 2030 ambient air quality standards 
that  will  put  the  EU  on  a  path  to  achieve  zero  air  pollution  at  the  latest  by  2050.  The 
standards are aligned more closely with the World Health Organization (WHO) updated 
air  quality  guidelines  for  key  air  pollutants5.  These  more  ambitious  ambient  air  quality 
standards mean that Member States will need to reduce their emissions of air pollutants 
further.  

Under  the  second  pillar,  the  NEC  Directive,  since  2022  the  EU  has  carried  out  yearly 
compliance checks against the national emission reduction commitments for 2020-2029 
for  the  five  most  harmful  transboundary  air  pollutants.  The  first  compliance  check  in 
2022 using 2020 emission data revealed that much more action is needed, in particular 
to reduce ammonia emissions. 

The  third  pillar  is  to  tackle  emissions  at  source.  To  this  end,  several  revisions  of 
legislation  have  been  finalised  since  the  Third  Clean  Air  Outlook6.  These  include 
finalising  the Euro 7  emission  standard for  new  motor vehicles7;  revising  the  Industrial 

https://europa.eu/eurobarometer/surveys/detail/2660 

1 
2  Directive (EU) 2024/2881 on ambient air quality and cleaner air for Europe. 
3  Directive (EU) 2016/2284 on the reduction of national emissions of certain atmospheric pollutants. 
4 

Sulphur  dioxides  (SO2),  nitrogen  oxides  (NOx),  ammonia  (NH3),  non-methane  volatile  organic 
compounds (NMVOC) and fine particulate matter (PM2.5). 

5  WHO (2021) WHO Global Air Quality Guidelines. 
6   COM(2022) 673 final 
7   Regulation (EU) 2024/1257 of the European Parliament and of the Council of 24 April 2024 on type-
approval  of  motor  vehicles  and  engines  and  of  systems,  components  and  separate  technical  units 
intended for such vehicles, with respect to their emissions and battery durability (Euro 7). 

1 

 
 
 
Emissions Directive8, and importantly, the suite of Fit for 55 and REPowerEU initiatives. 
The work to revise the ecodesign criteria for solid fuel boilers and local space heaters is 
still ongoing. 

This  fourth  edition  of  the  Clean  Air  Outlook  assesses  the  prospects  of  achieving  the 
objectives of the NEC Directive for 2030 and beyond, in terms of reducing emissions of 
air pollutants and subsequent impacts on air quality, health, ecosystems and the economy. 
It complements the second report on implementation of the NEC Directive published in 
July  20249  by  providing  a  forward-looking  analysis.  This  analysis  builds  on  the  above 
legislative revisions and on the Communication for a 2040 climate target for the EU and 
its impact assessment10. 

The  Fourth  Clean  Air  Outlook  directly  contributes  to  the  Second  Zero-Pollution 
Monitoring and Outlook report by the European Environment Agency (EEA) and 
the Joint Research Centre (JRC)11 by analysing the prospect of achieving the two clean 
air-related zero-pollution action plan12 targets. The targets are:  

− 

− 

to  reduce,  by  2030  in  the  EU,  by  more  than  55%  the  health  impacts  of  air 
pollution (expressed as premature deaths); and  
to  reduce  by  25%  the  ecosystems  where  air  pollution  threatens  biodiversity 
(compared to 2005 levels). 

Finally,  the  Fourth  Clean  Air  Outlook  provides  an  updated  analysis  to  feed  into  the 
ongoing evaluation of the NEC Directive, due to be finalised by the end of 202513, and 
highlights the co-benefits for climate and air quality of reducing methane emissions. 

2.  STATE OF AIR POLLUTANT EMISSIONS AND AIR QUALITY  

2.1.  Current air pollutant emissions and air quality situation 

Over the years, the EU has reduced emissions of the main air pollutants, though at very 
different  paces  depending  on  the  type  of  pollutant.  As  seen  in  Figure  1,  the  EU  has 
already reduced emissions of SO2 by over 80%, NOx by 50% and NMVOC and PM2.5 by 
over 30% since 2005. However, emissions of  ammonia (NH3), over 90%  of which are 
generated by the agricultural sector, remain worryingly flat and have even increased in 
recent years in some Member States. 

8  Directive (EU) 2024/1785 of the European Parliament and of the Council of 24 April 2024 amending 
Directive  2010/75/EU  of  the  European  Parliament  and  of  the  Council  on  industrial  emissions 
(integrated  pollution  prevention  and  control)  and  Council  Directive  1999/31/EC  on  the  landfill  of 
waste. 

9   COM(2024) 348 final. 
10   COM(2024) 63 final, underpinning impact assessment: SWD(2024) 63 final. 
11  https://environment.ec.europa.eu/strategy/zero-pollution-action-plan/zero-pollution-targets_en 
12  COM(2021) 400 final. 
13  Under  Article 13  of  the  NEC  Directive.  More  details  on  the  evaluation  including  the  evaluation 

questions identified is available on Have your say as well as on the Commission’s Air website. 

2 

 
 
 
Figure 1: Trend in EU-27 emissions, 2005-2022 (% of 2005 levels) 

Source: European Environment Agency, based on Member States’ air pollutant emission inventories 

Despite  an  overall  decrease  in  air  pollution,  the  impacts  of  pollution  on  health  and 
ecosystems remain problematic. In 2022, most people living in urban areas in the EU 
were exposed to air pollution at levels that damage their health14. The EEA estimates 
that  air  pollution  is  the single  largest  environmental  health  risk  in  Europe  and  one  that 
disproportionately affects sensitive and vulnerable social groups15. Therefore, tackling air 
pollution is also a matter of fairness and equality.  

Some 239 000 premature deaths are attributable to exposure to fine particulate matter in 
the  EU  annually,  70 000  to  ozone  and  48 000  to  nitrogen  dioxide16.  The  EEA  also 
estimated  that  in  2022,  73%  of  ecosystems  in  the  EU  were  above  the  critical  load  for 
eutrophication. Large proportions of forests and agroecosystems were exposed to ground-
level ozone concentrations above threshold values, resulting in damage to vegetation and 
yields17. 

2.2.  Compliance with EU clean air legislation 

After  reviewing  the  2020  emission  inventories  submitted  by  Member  States  in  202218, 
the  Commission  concluded  that  14  Member  States  did  not  meet  their  reduction 
commitments for at least one pollutant. In 11 of these Member States, ammonia is one 
of the pollutants emitted in excess. As a consequence, the Commission issued letters of 

14  European Environment Agency (2024) Europe’s air quality status 2024. 
15  EEA Report No 22/2018. 
16  https://www.eea.europa.eu/en/analysis/publications/harm-to-human-health-from-air-pollution-2024. 

This estimate is based on air pollution concentration  monitoring and  only includes premature deaths 
attributable  to  air  pollution  above  WHO  air  quality  guidelines  level,  unlike  other  estimates  in  the 
remainder of this report from modelling results in Klimont et al., ‘Support to the development of the 
fourth Clean Air Outlook’, IIASA et al., 2025 [IIASA 2025], and which reflect all impacts (including 
below WHO guidelines level), to remain consistent with previous Clean Air Outlook analyses. 

17  https://www.eea.europa.eu/en/analysis/publications/impacts-of-air-pollution-on-ecosystems-in-europe 
18  Emission  inventories  are  reported  with  a  two-year  time  lag,  which  means  that  compliance  checks 

against the 2020-29 obligations took place for the first time in 2022. 

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formal notice to 14 Member States for 19 cases of non-compliance19. Based on the 2023 
compliance  assessment,  the  Commission  followed  up  by  issuing  additional  letters  of 
formal notice and reasoned opinions in November 202320. The 2024 inventories indicate 
slight improvements, though the compliance situation for ammonia remains difficult with 
eight Member States still failing to meet their reduction commitment21. 

The  2022  emission  data  submitted  by  Member  States  in  2024  highlight  that  several 
Member States need to take far stronger action to reduce emissions of several pollutants 
to fulfil their more ambitious emission reduction commitments for 2030 onwards. An 
EEA analysis22 shows that 8 and 5 Member States respectively need to lower their PM2.5 
and  NOx  emissions  by  over  30%  between  2022  and  2030.  For  NMVOC  and  ammonia 
emissions, 8 and 10 Member States respectively need to reduce their emissions by over 
10% between 2022 and 2030. 

Member States set out their policies and measures to  tackle air pollution in national air 
pollution  control  programmes23.  The  NEC  Directive  requires  Member  States  to  update 
their programmes at least every four years, or earlier24 if the latest inventory or projected 
emissions data indicate that they will not meet the reduction commitments. The second 
Commission  implementation report  on the  NEC  Directive25  summarises  the assessment 
of Member State submissions of national air pollution control programmes. 

In  terms  of  compliance  with  the  Ambient  Air  Quality  Directives,  as  of  January  2025, 
there were 25 ongoing infringement cases due to poor application of the Ambient Air 
Quality Directives by 16 Member States. Proceedings before both the Court of Justice of 
the EU and national courts confirm that in many cases, air quality plans were inadequate 
and/or insufficient measures were adopted to reduce air pollution. 

3. 

IMPLEMENTATION OF THE NEC DIRECTIVE 

3.1.  Changes in legislation and policy context 

Since the Third Clean Air Outlook, Council and Parliament have finalised the legislative 
work on all files related to the 2021 Fit for 55 package, which increase the EU’s ambition 
to  reduce  greenhouse  gas  emissions  to  at  least  55%  below  1990  levels  by  2030.  The 
ambition  level  was  brought  up  further  through  the  REPowerEU  plan26  to  end  the  EU’s 
dependency on gas, oil and coal imports from Russia.  

In  February  2024,  the  European  Commission  presented  a  Communication  for  a  2040 
climate  target  for  the  EU  and  its  accompanying  impact  assessment  and  recommended 
reducing the EU’s net greenhouse gas emissions by 90% in 2040 relative to 1990 levels. 
The evolution of the EU’s energy system in the ‘S3 scenario’ of that impact assessment, 

19   https://ec.europa.eu/commission/presscorner/detail/EN/inf_23_142 
20   https://ec.europa.eu/commission/presscorner/detail/en/inf_23_5380. 
21   The outcomes of the 2024 inventory review are summarised in the horizontal review report 2024. 
22  https://www.eea.europa.eu/publications/national-emission-reduction-commitments-directive-2024; 

these figures are based on Member States’ data as submitted, not taking in account the Commission’s 
review of these submissions. 

23   Available at https://environment.ec.europa.eu/topics/air/reducing-emissions-air-pollutants/national-air-

pollution-control-programmes-and-projections_en. 

24   Such earlier update includes an update of policies and measures to tackle air pollution. 
25   COM(2024) 348 final. 
26  COM(2022) 230. 

4 

 
 
which  illustrates  a  pathway  to  meet  the  greenhouse  gas  emission  reductions  of  the 
preferred  target  option,  has  been  taken  into  account  as  basis  for  the  modelling 
underpinning this Fourth Clean Air Outlook. More ambitious energy and climate policies 
generally  bring  co-benefits  for  air  quality  by  reducing  emissions  of  key  air  pollutants 
(PM2.5, NOx and SO2)27. 

In terms of emissions from transport, the analysis of the Fourth Clean Air Outlook builds 
upon the adopted Euro 7 emission standard and incorporates revised CO2 targets for 
cars, lorries and other heavy-duty vehicles. 

Finally,  this  Fourth  Clean  Air  Outlook  incorporates  the  changes  brought  in  by  the 
revised Industrial Emissions Directive (IED). The modelling assumes, as a minimum, 
compliance with the upper end of the emission levels associated with the best available 
technique  conclusions  (BAT-AELs)28.  Reflecting  the  outcome  of  the  IED  revision 
implied  undoing  some  of  the  model  developments  carried  out  for  the  Third  Clean  Air 
Outlook, e.g. the proposal to cover large cattle farms. 

3.2. 

Prospects  for  achieving  the  NEC  Directive’s  emission  reduction 
commitments  

According to  the  results of the  Fourth  Clean Air Outlook,  only  four  Member States29 
are  on  course  to  achieve  in  2030  all  their  emission  reduction  commitments,  under 
current  national  measures  and EU legislation and in  line with the  above changes  in  the 
policy  context  (this  is  the  ‘baseline’  policy  scenario30).  All  other  Member  States  must 
take  additional  measures  to  fulfil  their  obligations.  Action  is  needed  in  particular  to 
reduce ammonia emissions, as 21 Member States need to make reductions by 2030. 
Table  1  shows  the  Member  States  projected  to  miss  their  emission  reduction 
commitments by type of pollutant. These forward-looking modelling results confirm the 
trend observed in the data analysed by EEA (see section 2.2). 

Looking at the modelling for emission levels in 2025 and at whether Member States are 
on  a  linear  reduction  trajectory31  to  reach  their  more  ambitious  reduction  commitments 
for  2030,  only  eight  Member  States32  are  on  course  to  reduce  all  five  pollutants  to  the 
extent needed. Swift action must be taken by the remaining Member States, in particular 
to  reduce  ammonia  emissions.  Estimates  indicate  that  17  Member  States  are  not  on  a 
linear reduction trajectory in 2025 for ammonia emissions. Using all available technical 

27  The  scenarios  in  the  impact  assessment  on  the  2040  climate  target  (SWD(2024)  63  final)  project 

reductions of around 60-75% for SO2, NOx and PM2.5 emissions over 2015-2040. 

28   The revised IED will lead to a greater emphasis on, and application of, the lower end of the BAT-AEL 
ranges. As such, the revised IED will likely lead to reductions beyond those assumed here, however, it 
is currently not possible to estimate the extent of that further reduction. 

29  EE, EL, IT, FI. 
30   For a description of all scenarios mentioned in this report, see  section 3 of IIASA (2025). All results 

presented here stem from the GAINS model (https://gains.iiasa.ac.at/gains). 

31  Under Article 4(2) of the  NEC Directive, indicative levels of the 2025 emissions are  calculated by a 
linear  reduction  trajectory  established  between  the  emission  levels  set  by  the  emission  reduction 
commitments for 2020 and the emission levels  set by the emission reduction commitments for 2030. 
The  assessment  is  hence  made  against  a  maximum  allowed  emission  level  that  is  the  average 
maximum allowed level resulting from the 2020-29 and 2030 emission reduction commitments. 

32  BE, CY, EE, EL, IT, MT, AT, FI. 

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measures33 would enable all Member States to meet their 2030 commitments, except for 
one Member State as regards NH3. 

The  analysis  confirms  the  rather  worrying  compliance  prospects  for  NH3  that  previous 
Outlook  reports  also  highlighted.  Since  the  Third  Outlook  report,  there  has  been  an 
increase  in  the  number  of  countries  expected  not  to  meet  the  PM2.5  emission  reduction 
commitments. This can be explained by increases in estimated emissions from solid fuel 
combustion  (biomass  and  coal)  in  the  residential  sector,  linked  to  new  information 
integrated  in  the  GAINS  model  on  the  structure  of  installations,  wood  and  coal 
consumption and emission factors. 

Table 1: Member States projected to miss their emission reduction commitments 

Scenario 

Baseline 

Year 

2025 

Baseline 

2030 

NH3 

NMVOC 

NOx 

PM2.5 

SO2 

BG, CZ, DK, DE, IE, ES, 
FR, HR, LV, LU, HU, 
NL, PL, PT, SK, SI, SE 

BE, BG, CZ, DK, DE, IE, 
ES, FR, HR, CY, LV, LU, 
HU, NL, AT, PL, PT, RO, 
SK, SI, SE  

LT 

LT, RO 

LT, HU, 
SI  

MT, RO 

CZ, HU, 
PL, RO, 
SI 

CZ, DK, 
CY, ES, 
HU, PT, 
RO, SI 

- 

- 

- 

All technical 
measures 

2030 

NL  

- 

- 

- 

Source: Based on IIASA (2025) modelling results. 
Note: For 2025, the assessment is carried out against the linear reduction trajectory, as explained in Footnote 31. ‘-’ 
means all Member States are projected to meet the targets. 

3.3.  Extending the range of emissions covered under the NEC Directive 

The  modelling  underpinning  this  edition  of  the  Clean  Air  Outlook  follows  a  new 
approach  as  regards  including  condensable  particulate  matter  emissions.  These  are 
emissions  initially  in  vapour  form  (inside  or  close  to  the  stack)  that  transform  into 
particulate  matter  when  discharged  into  ambient  air.  It  is  important  to  include  these 
emissions  as  they  impair  the  quality  of  the  air  we  breathe.  Particularly  in  domestic 
heating,  condensable  particulate  matter  emissions  are  significant  and  are  estimated  to 
represent about the same level as filterable emissions. As a result of recent improvements 
in the official reporting of emissions with condensables34, the baseline model set-up now 
includes  a  consistent  representation  of  the  condensable  part  of  particulate  matter 
emissions linked to the combustion of wood and coal in the residential sector35. 

Alternative assumptions were tested as part of the sensitivity analysis to see the effect of 
including  filterable  particulate matter  only  or including  a set  of  higher  emission factors 
that factor in  bad combustion practices.  The  prospects of meeting the PM2.5 emission 

33  Maximum technically feasible reduction scenario, referred to as ‘all technical measures’. 
34   This followed the introduction of a set of emission factors including condensables in the EEA/EMEP 
Guidebook. According to IIASA (2025), five Member States do not include  the  condensable part of 
PM emissions from residential solid fuel combustion in their inventories (Austria, Estonia, Germany, 
Lithuania  and  Luxembourg).  The  GAINS  model  uses  country-specific  PM  emission  factors  that 
assume  that  the  condensable  fraction  is  included,  also  for  these  five  countries.  This  assumption  has 
been communicated to Member States during consultations with them that IIASA held in early 2024. 
35   In  the  Third  Clean  Air  Outlook,  condensables  were  consistently  included  in  the  sensitivity  analysis 

only. 

6 

 
 
 
reduction  commitments  barely  change  depending  on  these  assumptions36,  but  the 
total volume of emissions reported changes depending on the exact emission factor used. 

Another  improvement  to  the  modelling  of  real-world  emissions  is  to  include  NOX  and 
NMVOC  emissions  from  agriculture.  These  emission  sources  are  excluded  from  the 
compliance checks under the NEC Directive37 due to the lack of sufficiently reliable data 
when  the  commitments  were  set.  More  recent  data  now  allow  this  information  to  be 
incorporated  into  models.  Indeed,  if  these  emissions  were  to  be  included,  the  projected 
compliance status in several Member States would change.  

When including NOX emissions from agriculture, the prospects of compliance with 2030 
reduction  commitments  under  the  baseline  worsen.  The  level  of  non-compliance  is 
expected to rise from two Member States (MT, RO) to eight (DK, FR, HU, IE, LT, MT, 
RO,  SE).  When  including  NMVOC  emissions  from  agriculture,  non-compliance 
prospects under the baseline for 2030 also worsen, rising from three Member States (HU, 
LT, SI) to six Member States (HU, IE, LT, LU, SI, ES). This demonstrates that, despite 
not being currently required by the NEC Directive, additional action is needed in several 
Member States to unlock the full potential of the sector to mitigate air pollution. 

4.  PROSPECTS OF MEETING ZERO-POLLUTION OBJECTIVES ON CLEAN AIR 

4.1.  The EU’s 2030 clean air targets in the zero-pollution action plan 

The zero-pollution action plan includes two EU-level targets for 2030 related to clean air: 

1)  reduce by more than 55% the health impacts (expressed as premature deaths) of 

air pollution compared to 2005 figures; 

2)  reduce by 25% the EU ecosystem area where air pollution threatens biodiversity, 
expressed as ecosystem areas that have exceeded the ‘critical loads’ of nitrogen 
deposition (compared to 2005 figures). 

In line with the analysis summarised in the Third Clean Air Outlook, the EU is currently 
on  track  to  meet  the  zero-pollution  target  to  reduce  the  health  impacts  under  the 
baseline  scenario.  The  analysis  estimates  a  62%  reduction  in  the  number  of  premature 
deaths between 2005 and 2030. However, it is not on track to meet the ecosystem target 
on time, with only a 19% reduction expected in areas at risk between 2005 and 203038. 

4.1.1.  Health-related target and overall health impacts across scenarios 

Background concentration of air pollutants and population exposure 

Even under the baseline scenario, pollutant concentrations are expected to fall over time 
and,  by  2030,  very  few  areas  in  the  EU  are  projected  to  exceed  20  µg/m3  for  PM2.5. 
However, large areas are still projected to have pollution concentration levels above the 
currently recommended WHO air quality guideline of 5 µg/m3 in 2030, and even in 2050. 

36   This  masks some changes in the margin of compliance, which changes in different directions across 
Member States. This includes cases where the inclusion of high emission factors improves the margin 
of compliance. 

37  Article 4(3)(d) of the NEC Directive. 
38   The 25% reduction target is expected to be met between 2040 and 2045. 

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Translating  background  concentration  levels  into  impacts  on  the  health  of  the  EU 
population  shows  that  the  number  of  people  living  in  areas  with  clean  air  is  set  to  rise 
considerably.  While  this  would  be  a  significant  improvement,  further  policy  action  is 
needed to limit the negative health impacts also for the (roughly) remaining half of 
the EU population in 2050 still exposed to pollution above the 2021 WHO guidelines. 

As seen from Figure 2, the results vary for individual countries, though all are projected 
to  see  a  steady  improvement  both  in  background  concentrations  and  the  share  of 
population exposed to pollution. It also shows that for some countries, under a scenario 
that  assumes  all  Member  States  meet  their  emission  reduction  commitments,  further 
improvements would be achieved by 2030. 

Figure 2: EU-27 population exposed to different concentrations of PM2.5 

Source: IIASA (2025) 
Note:  ‘ERC’  is  a  scenario  that  assumes  all  Member  States  meet  their  emission  reduction  commitments. 
MTFR is the ‘all technical measures’ scenario. 

Currently,  most of  the  EU population  (97%) live in areas with  NO2  pollution levels 
below the current EU limit of 40 µg/m3, and nearly 60% live in areas below the WHO 
guideline limit of 10 µg/m3 in 2025. By 2030, this is projected to increase to over 70% in 
all  scenarios,  reaching  over  80%  if  all  technical  measures  are  implemented.  By  2050, 
under  all  scenarios,  well  over  95%  of  the  EU  population  is  projected  to  live  in  areas 
where pollution remains below the WHO-recommended level for NO2. 

Premature deaths and achieving the zero-pollution target 

Premature  deaths39  due  to  PM2.5  exposure  are  projected  to  fall  by  about  62-79% 
compared to 2005 figures, across all scenarios (including the baseline) by 2030 and 2050. 

39  The health impacts of air pollution extend beyond mortality and include morbidity. The impacts have 
been  analysed  and  are  monetised  in  order  to  assess  the  economic  impacts  as  well  as  the  benefits  of 
lower air pollution (see section 4.2). 

8 

 
 
 
Premature  deaths  will  fall  somewhat  faster 
commitments, with a much steeper reduction if they also take all technical measures.  

if  countries  meet 

their  reduction 

Provided all policies included in  the baseline  scenario achieve  the intended results, the 
EU is set to achieve the zero-pollution health target by a comfortable margin in 2030. 
This target is formulated at EU level,  but it also  translates into reductions in premature 
deaths of 55% or more at the level of most Member States individually. 

Figure  3: Cases  of  premature  deaths  attributable  to  exposure  to  total  PM2.5 
concentrations in the EU-27, in thousand cases per year 

Source: IIASA (2025). 
Note:  The  55%  marking  indicates  the  zero-pollution  target.  Only  anthropogenic  sources  of  PM2.5  are 
included, in line with the way the zero-pollution target was set. 

In absolute numbers40, while this projection shows that significant improvements should 
be  achieved  over  the  baseline  scenario,  it  still  means  an  estimated  220 000  premature 
deaths due to PM2.5 exposure in 2030. Taking all technical measures would reduce the 
number of premature deaths by over 37 000. 

Exposure  to  NO2  is  projected  to  cause  around  68 000  premature  deaths  under  the 
baseline  scenario  in  2030.  Taking  all  technical  measures  would  reduce  deaths  by  over 
11 000.  Between  2030-2050,  the  number  of  premature  deaths  attributable  to  NO2 
exposure is set to more than halve. Exposure to ground-level ozone is projected to cause 
around  65 100  premature  deaths  under  the  baseline  scenario  in  203041,  varying  only 
slightly by scenario and over time. 

40  Using the same methodological approach as in the Second Clean Air Outlook, which was the basis for 

setting the zero-pollution targets. 

41   This is a rather pronounced change compared  with the estimated 50 000 deaths attributable to ozone 
exposure in CAO3. This is due to the more developed and detailed modelling approach taken here, as 
explained in IIASA (2025). 

9 

 
 
 
4.1.2.  Ecosystem-related target and overall ecosystem impacts 

Air  pollution  affects  ecosystem  health  through  acidification,  eutrophication  and  ozone 
impacts.  Modelling  results42  show  a  significant  improvement  over  time  as  regards 
acidification: under the baseline scenario, by 2030, less than 3% of the ecosystem area in 
the EU would suffer from acid deposition exceeding critical loads, compared to 15% in 
2005.  This  demonstrates  the  benefits  of  the  significant  reduction  in  SO2  emissions 
already achieved over the past decades. The benefits would be even greater if all Member 
States meet their emission reduction commitments, or all technical measures are taken. 

In  line  with  previous  Outlook  reports,  the  situation  is  considerably  less  positive  when 
looking at the impacts of air pollution on eutrophication43. This is linked to the current 
projection that the EU will not achieve the zero-pollution ecosystem target under baseline 
policies  only.  In  this  scenario,  69%  of  EU  ecosystems  would  still  suffer  from 
eutrophication  in  2030  (down  from  86%  in  2005).  Under  the  baseline  conditions, 
protected  areas  would  continue  to  be  highly  affected  in  2030,  with  60%  of  Natura 
2000  areas  suffering  from  eutrophication  (down  from  78%  in  2005).  If  all  technical 
measures are taken, the share of EU ecosystems suffering from eutrophication would fall 
to 59% (and to 49% in Natura 2000 areas) by 2030.  

Figure 4: Ecosystems in the EU-27 exceeding the critical loads for eutrophication 

Source: IIASA (2025) 
Note: The marked 25% line indicates the zero-pollution target. 

The GAINS model was used to estimate a cost-effective set of measures needed to reach 
the 25% reduction target at EU level (‘ZPAP’ scenario in Figure 4). This is achievable by 
taking  additional  measures  to  limit  ammonia  emissions  in  all  Member  States 
(ammonia being the air pollutant with the greatest impact on ecosystems). Such measures 
would  tackle  emissions  from  cattle  manure  (in  particular,  spreading  manure  on  fields), 

42  Estimation  of  ecosystem  impacts  follows  the  same  methodology  applied  in  the  Third  Clean  Air 
Outlook,  based  on  the  same  critical  load  database  compiled  through  the  Coordination  Centre  for 
Effects of the Working Group on Effects under the UNECE Air Convention (see IIASA, 2025). 

43  Assessed as the area of ecosystems where nitrogen deposition exceeds the critical loads. 

10 

 
 
 
 
followed  by  measures  to  mitigate  emissions  from  using  mineral  fertilisers  and  from 
breeding pigs and poultry.  

Altogether, these measures would reduce ammonia emissions at EU-27 level by 14% in 
2030  compared  to  the  baseline  scenario,  while  meeting  the  zero-pollution  target  on 
eutrophication.  Adopting  these  measures  would  also  significantly  increase  the 
prospects  of  meeting 
the  NEC  Directive’s  ammonia  emission  reduction 
commitments, and fewer Member States would fail to achieve the commitments in 2030 
(from 21 to 7).  

The  NEC  Directive  refers  to  these  measures  either  as  compulsory  or  voluntary 
measures44.  During  the  process  of  the  ongoing  evaluation  of  the  NEC  Directive,  the 
Commission will assess whether this list of measures and their compulsory or voluntary 
status  are  still  fit  for  purpose.  It  will  also  take  into  account  relevant  findings  from  the 
ongoing process to revise the UNECE Air Convention guidance document on preventing 
and  abating  ammonia  emissions  from  agricultural  sources45.  In  the  meantime,  Member 
States,  in  particular  countries  facing  challenges  in  meeting  current  or  future  emission 
reduction  commitments  for  ammonia,  are  strongly  encouraged  to  step  up  action  to 
implement the mitigation measures by: 

–  adopting national legislation to make certain agricultural practices binding; 
–  promoting  these  practices  through  communication  and  awareness-raising  campaigns, 

including by providing farm advice under the common agricultural policy. 

These  efforts  should  form  part  of  an  integrated  approach  to  nitrogen,  notably  from 
agriculture, including measures to tackle the eutrophication of aquatic ecosystems caused 
by  nitrates  leaching  and  running  off  from  agricultural  fields  and  by  pollution  of 
freshwater  resources,  including  groundwaters.  The  Commission  is  currently  evaluating 
the Nitrates Directive and will assess the need for further steps in light of this evaluation, 
currently planned for publication in the second half of 2025. 

The  implementation  of  the  Nature  Restoration  Regulation46  is  expected  to  result  in 
additional  efforts  to  reduce  pollution  pressures  on  ecosystems,  as  well  as  to  increase 
overall ecosystem resilience. Urban ecosystem restoration may also provide nature-based 
solutions to mitigating urban air pollution’s impacts on human health. 

4.2.  Economic impacts 

The economic impacts  of air pollution are numerous. Most impacts  are not  reflected in 
market  prices,  in  particular  direct  health  effects  of  pollution.  Damage  to  ecosystems 
(including  agricultural  areas  and  forests)  and  to  materials  from  air  pollution  also 
including  some 
generates  costs.  Air  pollution  also  generates 
macroeconomic  consequences  that  are  reflected  in  market  prices.  The  costs  of  air 

impacts, 

indirect 

44  Annex III, part 2. 
45 
The 

2014 

here: 
https://unece.org/DAM/env/documents/2012/EB/ECE_EB.AIR_120_ENG.pdf  while  a  new  version  is 
expected to be available in 2025. 

document 

available 

version 

the 

of 

is 

46   Regulation (EU) 2024/1991 of the European Parliament and of the Council of 24 June 2024 on nature 

restoration and amending Regulation (EU) 2022/869. 

11 

 
 
pollution  abatement  measures  should  therefore  be  weighed  against  the  benefits  these 
measures bring to society, by attributing a monetary value to these benefits47. 

Under the baseline scenario, the health damages caused by air pollution are estimated at 
between  EUR 290-950 billion  per  year  by  2030.  They  are  estimated  to  fall  to  between 
EUR 191-745 billion by 205048, as population exposure to air pollution decreases. When 
considering only the impacts to exposure to levels of air pollution above WHO (2021) 
guidelines, the health damages are estimated at between EUR 105-347 billion per year 
by 2030. They are estimated to fall to EUR 35-124 billion by 2050. Under the scenario 
with  all  technical  measures  taken,  health  damages  from  exposure  to  above-WHO 
guideline levels are projected to fall by over a third compared to the baseline by 2030. 

The economic  cost of ecosystem damages due to air pollution49 ranges from EUR 3.7-
11.0 billion in 2030.  This is  projected to  fall  only marginally  to  EUR 3.3-9.9 billion  by 
2050, reflecting the only modest reduction in Natura 2000 areas subject to eutrophication 
under  the  baseline.  The  cost  of  damages  to  crops  and  to  forests  are  estimated  at 
EUR 13.0-18.0 billion  in  2030  respectively  under  the  baseline,  only  marginally 
decreasing if all technical measures are adopted. The reason for this is that, factoring in 
only  EU  mitigation  action,  there  will  be  a  limited  improvement  in  ozone  levels,  which 
drive  damage  to  agriculture  and  forests  (see  the  next  section).  The  economic  cost  of 
damages  to  materials  due  to  air  pollution  is  estimated  to  reach  EUR 742 million  in 
2030, before falling to EUR 384 million in 2050 under the baseline scenario. 

Compared to  current  policies, the different  scenarios are projected to  generate  different 
levels  of  non-market  benefits  and  different  levels  of  additional  costs  for  the  pollution 
abatement measures needed. Across the scenarios assessed here, the analysis of benefits 
to  costs  reveals  net  direct  benefits  (benefits  minus  costs)  compared  to  the  baseline 
scenario. 

Measures to reduce air pollution and their positive effects on air quality also have wider 
macroeconomic effects50 reflected in the market. Pollution abatement measures generate 
both a cost for some sectors and a business opportunity for others, while air quality has 
impacts on both labour and crop productivity and therefore on the economy as a whole. 
Based  on  recent  assumptions  on  labour  productivity  effects51,  all  scenarios  leading  to 
cleaner  air  would  increase  EU  GDP  in  2030  compared  to  the  baseline  scenario  (the 
same holds for 2040 and 2050, Figure 5).  

47  For a description of the methodology underpinning the results in this section, see IIASA (2025). 
48  The ranges reflect whether mortality is valued using the value of a life-year or the value of statistical 
life;  values  are  expressed  per  year,  in  2015  prices.  A  conservative  approach  has  been  taken  that 
excludes  NO2  impacts  where  there  is  potential  for  the  effects  to  be  double  counted  against  the 
quantification of PM2.5 effects. 

49  Those impacts are estimated through the loss of ecosystem services only in Natura 2000 areas due to 

eutrophication. They therefore underestimate the total loss in ecosystem services. 

50   The effects have been calculated by the European Commission Joint Research Centre using the JRC-
GEM-E3  model  (https://joint-research-centre.ec.europa.eu/gem-e3_en).  For  more  details,  see  section 
5.5 of IIASA (2025). 

51  Dechezleprêtre,  A.,  Rivers,  N.,  &  Stadler,  B.  The  economic  cost  of  air  pollution:  Evidence  from 

Europe. OECD Economics Department Working Papers, 2019 [OECD, 2019]. 

12 

 
 
Figure 5: Macroeconomic market effects of clean air policy scenarios, in % change in 
EU GDP compared to the baseline scenario 

Source: IIASA (2025) based on JRC modelling with OECD (2019) assumptions on labour productivity. 

This  shows  the  overriding  positive  economic  effects  of  pollution  abatement  measures. 
The  net  effect  is  greatest  under  the  scenario  when  all  technical  measures  are  taken 
(+0.24%), with more limited effects in the 2030 scenarios where the emission reduction 
commitments and zero-pollution targets are met. The sectoral distribution of the effects 
shows  that  only  the  livestock  sector  would  see  a  small  reduction  (below 2%)  in  output 
compared to the baseline scenario. 

5.  CLEAN  AIR  AND  CLIMATE  ACTION  CO-BENEFITS  OF  REDUCING  METHANE  AND 

BLACK CARBON EMISSIONS 

The  NEC  Directive  recognises  the  link  between  air  pollution  on  the  one  hand  and 
methane  and  black  carbon,  two  key  short-lived  climate  forcers,  on  the  other.  Member 
States must report national emissions of black carbon where data are available; currently 
all but two Member States do so. The Commission is looking at methane emissions in the 
ongoing  evaluation  of  the  NEC  Directive  and  is  analysing  whether  the  co-legislators’ 
decision,  at  the  time  of  its  adoption,  not  to  include  methane  amongst  the  regulated  air 
pollutants has hampered stronger synergies with climate and other policies. 

Methane is both a potent climate forcer and a precursor to ground-level ozone pollution. 
Anthropogenic  emissions  of  methane  in  the  EU  come  mainly  from  agriculture  (56%), 
waste  (24%)  and  energy  (16%)52.  In  2024,  the  EU  Regulation  on  the  reduction  of 
methane  emissions  in  the  energy  sector  entered  into  force53.  Its  scope  extends  to  crude 
oil,  natural  gas  and  coal.  The  Regulation  contains  a  number  of  measures  which  taken 
together will contribute to  improving measurement and reporting of methane emissions 
in  the  EU;  reducing  methane  emissions  in  the  EU  via  mandatory  abatement  measures; 
increasing transparency on methane emissions in the EU and globally; and incentivising 
the  EU’s  international  partners  to  measure,  report  and  reduce  their  methane  emissions. 

52   Data from 2022 based on EEA greenhouse gases – data viewer (including the land-use sector). 
53   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. 

13 

 
 
 
 
However,  the  high  share  of  methane  emissions  from  agriculture  remains  largely 
unaddressed  in  the  EU.  Tackling  methane  as  a  precursor  to  ozone  will  help  Member 
States meet the more stringent ozone target values under the revised Ambient Air Quality 
Directive54. 

Black carbon55, or soot, forms fine particulate matter and generates negative impacts on 
health and on the environment. It is formed from the incomplete combustion of fossil fuel 
and wood. By absorbing light and heat in the air, black carbon also contributes to climate 
change.  When  deposited  on  ice  and  snow,  black  carbon  reduces  surface  albedo56, 
contributing to heating, particularly in Arctic regions. 

Reducing emissions of methane and black carbon can therefore produce benefits, both in 
terms  of  clean  air  and  in  terms  of  climate  change  mitigation,  increasing  the  benefit-to-
cost  ratio  of  their  abatement  measure.  The  modelling  carried  out  for  this  report  shows 
that baseline EU black carbon emissions  are expected to fall significantly (by 45%) 
between  2020  and  2030,  mostly  due  to  the  gradual  roll-out  of  the  ecodesign 
requirements for domestic heating appliances and less coal use in this sector. A quarter of 
the achieved reduction comes from the transport sector, primarily as a result of advanced 
Euro  emission  standards  for  motor  vehicles,  requiring  the  installation  of  efficient 
particulate  filters.  Even  greater  reductions  could  be  achieved  (66%  below  the  2020 
baseline level) if all technical measures are taken. 

Likewise, under this report’s baseline scenario, EU methane emissions are projected to 
fall  by  21% between 2020-2030 reaching  a 31% reduction  by 2040, driven by further 
action to decarbonise the economy and reduce emissions from waste management. 

However,  as  methane  is  transported  on  a  hemispheric  scale,  it  is  vital  to  complement 
action at EU level with global action. In November 2021, the EU co-convened together 
with  the  United  States  the  Global  Methane  Pledge57,  which  built  momentum  to 
accelerate  action.  It  puts  forward  a  voluntary  commitment  to  reduce  global  methane 
emissions by at least 30% from 2020 levels by 2030.  

In  parallel,  the  UNECE  Air  Convention  is  a  forum  to  explore  synergies  between 
international  rules  on  clean  air  and  climate.  In  particular,  the  process  to  revise  the 
Gothenburg Protocol (see next section) has opened discussions on the role of methane as 
an ozone precursor and therefore a pollutant of relevance to clean air policies. 

The modelling  carried out  here  confirms  that  there is  great  potential  globally to  reduce 
methane and other ozone precursors (NOx, NMVOCs and carbon monoxide). Joint action 
at global level reduces ozone concentrations in Europe, bringing many additional stations 
in compliance with the ozone target set in the Ambient Air Quality Directive, to a greater 
degree  than  if  the  EU  alone  took  action  or  if  global  action  is  taken  to  reduce  only 
methane,  not  the  other  precursors.  The  impact  of  additional  mitigation  is  particularly 
pronounced in 204058. 

54   The revised Directive maintains the target value of 120 μg/m3, but it reduces the number of calendar 

days that this value may be exceeded to 18 (down from 25) days averaged over three years. 

55   Elements from this description are sourced from the Climate and Clean Air Coalition. 
56  The ability to reflect sunlight. 
57  https://www.globalmethanepledge.org/. In January 2025, there were over 150 participating countries.  
58   There is more limited scope for additional mitigation by 2030, given the short time left to implement 

mitigation measures. 

14 

 
 
6.  TRANSBOUNDARY POLLUTION AND INTERNATIONAL ACTION 

Air  pollution  in  any  given  country  comes  from  multiple  sources:  domestic  emissions, 
emissions  generated  in  neighbouring  countries  and  natural  sources.  In  most  Member 
States, domestic sources are the main sources of pollution, and therefore the priority is to 
cut domestic emissions to reduce the background levels of air pollutants. However, the 
analysis  confirms  that  in  most  Member  States,  a significant  share  of  PM2.5  background 
concentration  is  generated  in  other  Member  States59.  This  reflects  the  transboundary 
nature  of  air  pollution,  which  justifies  taking  action  at  EU  level  as  air  pollution 
generated in one Member State may have negative impacts beyond national borders60. In 
addition,  the analysis shows that  a share of  air pollutant background concentration also 
comes  from  non-EU  countries,  at  varying  levels  depending  on  the  geography  of  the 
Member State61. Over time and with increasing stringency of EU air pollution abatement 
scenarios, the share of pollution from within the EU is projected to fall (due to additional 
action  in  the  EU),  increasing  the  relative  share  of  non-EU  sources  (in  particular  where 
non-EU  countries  do  not  reduce  air  pollution  at  a  similar  level  of  ambition).  This 
underlines  the  need  for  the  EU  to  take  stronger  action  bilaterally  (notably  in  the 
context  of  accession  and  neighbourhood  policies,  but  also  by  building  stronger 
international partnerships) and in multilateral fora such as the UNECE Air Convention. 

The NEC Directive obligations are, to a large degree, reflected at international level via 
the UNECE Air Convention and its amended Gothenburg Protocol. In recent years, more 
countries have ratified this Protocol, but there are still very few non-EU neighbouring 
countries that have ratified it. In the EU, two Member States62 are not yet Party to it 
but are close to finalising the ratification process. The Parties decided in December 2023 
that further revision is required in order to meet the objectives of the Protocol by stepping 
up action to reduce air pollution in Europe and North America. A priority in revising the 
Gothenburg Protocol will be to consider how to achieve further ratifications by countries 
that are currently not Party to it. The modelling underpinning this report will also be used 
as the basis for the analysis done in the process of revision, to identify possible emission 
reduction  commitments  for  the  region.  The  revision  process  is  expected  to  finish  by 
December 2026, but the group regularly adjusts the work programme and projected end 
date. As noted in  the previous section, the  Air  Convention Parties  continue to  examine 
the  potential  for  synergies  between  the  international  clean  air  and  climate  frameworks, 
how to attain further ratifications within the UNECE region, and how the Air Convention 
can do more to inspire similar international treaties. UNEA Resolution 6/1063 ‘Promoting 
regional cooperation on air pollution to improve air quality globally’, as agreed in March 
2024, also pursues this ambition. The Resolution has resulted in the creation of a new Air 
Quality Management Exchange Platform64 by the Climate and Clean Air Coalition. The 
aim  of  this  new  platform  is  to  facilitate  regional  and  sub-regional  exchange  of 
information  and  knowledge  on  best  practices  and  to  help  meet  the  WHO  Air  Quality 
Guidelines and interim targets. 

59   Detailed  results on  the origins of PM2.5 concentrations in EU Member States  are available in IIASA 
(2025).  While  other  air  pollutants  are  also  transported  across  borders,  the  report  analysed  PM2.5  in 
more detail given it is responsible for the highest impacts on health. 

60   The  efficiency  of  transboundary  pollutant  monitoring  can  be  improved  considerably  by  using  EU 

space data and services, such as the Copernicus Atmosphere Monitoring Service (CAMS).  

61  Smaller and more isolated Member States would benefit most from reductions in pollution in non-EU 
neighbouring countries, and from lower emissions from international shipping (especially islands). 

62   Italy and Poland. 
63   https://documents.un.org/doc/undoc/gen/k24/008/31/pdf/k2400831.pdf 
64   https://aqmx.org/ 

15 

 
 
7.  CONCLUSION 

The Fourth Clean Air Outlook confirms that air pollutant emissions in the EU continue 
to fall. This is good news for EU citizens, for the economy and for society. Over the past 
20 years, the EU has achieved substantial reductions in the emissions of most of the five 
main pollutants regulated under the NEC Directive.  Ammonia remains an exception, as 
emissions have fallen by much less, with eight Member States still failing to meet their 
emission  reduction  commitments  in  2022.  The  ongoing  evaluation  of  the  NEC 
Directive  will  shed  light  on  what  has  worked  well  in  implementing  the  Directive  and 
what the challenges are, including in meeting the emission reduction commitments. 

The  outlook  for  ammonia  emissions  remains  worrying.  The  projections  presented  here 
indicate  that  21  Member  States  could  miss  their  (more  ambitious)  2030  emission 
reduction  commitments.  These  Member  States  must  take  significant  additional  action 
to  reduce  ammonia  emissions  at  source  by  promoting  good  agricultural  practices, 
including as part of Member States’ implementation of the common agricultural policy. 
Additional  action  is  also  needed  to  limit  emissions  of  PM2.5,  for  which  eight  Member 
States are currently projected to miss their 2030 reduction commitments. 

Overall,  the  EU  is  on  track  to  meet  the  health-related  target  of  the  zero-pollution 
action plan. However, it is still not on track to meet the ecosystem-related target in 2030. 
This emphasises the need to do more to reduce ammonia emissions. All in all, the results 
from this analysis show that, while collectively the EU and its Member States have made 
clear  progress,  more  action  is  needed  to  reduce  the  negative  health  and  environmental 
impacts of air pollution, in line with the EU’s zero-pollution ambition and in full synergy 
with  the new Commission’s  commitment  to  achieve  sustainable prosperity. It  is  also  in 
line with the process to revise the Gothenburg Protocol. Applying a One Health approach 
to tackling air pollution, which recognises that human, animal, and environmental health 
are interconnected, is a promising way forward to achieving cleaner air. 

For the expected reductions  presented here  to  materialise,  it is  important to implement 
existing  legislation  in  full  and  to  draw  on  the  support  available  to  the  Member  States 
from the Commission to this end65. This includes Member State action to meet the more 
ambitious air quality standards that have just been adopted under the revised Ambient Air 
Quality  Directive.  Additional  action  would  further  reduce  the  health  and  ecosystem 
impacts of air pollution and generate macroeconomic gains. An ambitious climate target 
for  2040  will  not  only  consolidate  and  strengthen  the  EU’s  climate  ambition  but  also 
generate co-benefits of clean air to both improve public health and boost the economy66. 

65 

EU 

through 

support, 

Including 
(https://ec.europa.eu/info/funding-tenders/find-funding/eu-funding-programmes/technical-support-
instrument/technical-support-instrument-tsi_en)  and  EU-funded  research  and  innovation  initiatives 
(https://research-and-
related 
innovation.ec.europa.eu/document/c9d4c0b5-f85e-4599-986d-e6b2438229fc_en). 

remediation 

Instrument 

prevention 

Technical 

pollution 

Support 

such 

and 

the 

the 

air 

as 

of 

to 

66  See SWD(2024) 63 final, Part 1, section 6.3. 

16 

 
 
ANNEX: METHODOLOGICAL DIFFERENCES WITH THE THIRD CLEAN AIR OUTLOOK 

Key updates since the Third Clean Air Outlook 

–  The  baseline  scenario  reflects  more  recent  adopted  and  proposed  EU  policies.  In 
particular,  it  builds  on  the  modelling  carried  out  for  the  impact  assessment 
accompanying  the  2040  climate  target  Communication  (‘S3  scenario’,  which 
illustrates a pathway to meet the greenhouse gas emission reductions of the preferred 
target option in that impact assessment), notably regarding the evolution of the EU’s 
energy  system.  It  now  integrates  the  revised  IED,  whereas  CAO3  was  based  on  the 
Commission’s  legislative  proposal,  which  was  more  ambitious,  in  particular  in 
including large cattle farms in the regulated activities. 

–  The  GAINS  model  was  used  to  calculate  emissions  of  air  pollutants  as  well  as 
concentrations  of  PM2.5  and  NO2,  following  the  same  approach  and  model  version 
used  for  CAO3.  Ozone  concentrations,  however,  were  calculated  using  the  EMEP 
model67,  which  is  different  from  CAO3  where  these  were  calculated  also  using 
GAINS. 

–  The baseline scenario was updated to reflect as far as possible Member States’ latest 
emission inventories, projections and policies and measures by taking into account the 
input received from Member States during baseline consultations. 

–  The baseline scenario now includes a consistent representation of the condensable part 
of  particulate  matter  emissions,  whereas  in  CAO3  this  was  only  used  for  the 
sensitivity analysis. 

–  An updated methodology was used to assess health impacts. While the methodology 
remains  largely  in  line  with  CAO3,  the  morbidity  impacts  for  PM2.5  and  NO2  are 
estimated  based  on  new  work  under  the  EMAPEC  (‘Estimating  the  Morbidity  from 
Air Pollution and its Economic Consequences’) study coordinated by the WHO68. 

A more comprehensive  description of  the updates made to the modelling framework is 
available in IIASA (2025). 

67   The chemical transport model developed and maintained by the Meteorological Synthesizing Centre-
West (MSC-W) of the European Monitoring and Evaluation Programme (EMEP), see Simpson et al. 
(2012) https://doi.org/10.5194/acp-12-7825-2012 for a general description. 

68   https://doi.org/10.1097/EE9.0000000000000314 

17