The implementation of the first Daughter Directive on Air Quality  had a considerable effect on decision-making concerning large scale infrastructure projects. It was the Dutch administrative court that enforced the air quality standards in the Netherlands by ruling that the limit values are absolute standards to be applied at all levels of decision-making. Faced with the consequences of this interpretation the Dutch government tried to soften the economic and social effects of the court’s policy. This analysis of the debate that followed illustrates the two opposing approaches. The first approach is to interpret EC air quality standards  literally, meaning that the limit values have to be applied by all competent authorities. Those supporting the second approach argue that the limit values must be attained, in the first place, by national measures dealing with the sources of pollution, making use of technical solutions. The Dutch government has shifted slightly from the first to the second approach, as is clear from the Air Quality Order of 2005. However, it remains doubtful whether this will be sufficient to lift the current deadlock on infrastructure projects and attain the environmental limit values.

I.  Introduction

Recently there has been considerable turmoil in the Netherlands concerning decision-making on large scale infrastructure projects. The reason for this turmoil is the Dutch Air Quality Order  (Besluit Luchtkwaliteit) which implemented the Daughter Directive concerning limit values for sulphur dioxide, nitrogen dioxide, suspended particulate matter and lead in the air (Directive 99/30/EC). Some of the limit values set by the Directive, and accordingly by the Air Quality Order, came into force at the beginning of 2005, while others will not come into force until 2010. It is clear that the limit values for several pollutants will be very difficult to attain in the Netherlands, specifically, NO2 (nitrogen dioxide) and PM 10 (particulate matter). The most important causes of pollution are traffic and industrial activities (in some cases outside the Dutch borders) as well as natural sources, like sea salt. Limit values for other substances do not cause serious problems.     

      Since April 2004 the Dutch administrative court (Administrative Law Division of the Council of State) has examined a number of administrative decisions concerning permits for industrial installations, the development of industrial areas and the broadening of motorways which may affect air quality, with a view to the requirements of the Air Quality Order, and set them aside where they conflicted with the Order. The main reason for this was that the limit values set by the First Daughter Directive were interpreted as absolute limit values. Therefore it is not just a matter of an increase in the burdens for the administration in preparing decisions on infrastructure projects, as was the case when the court first applied the Habitat and Birds Directives, but whether the proposed projects will actually be able to take place at all. The impact of these decisions has been considerable. It has been said that the Netherlands has come to “a deadlock” due to this new case law.

This article will analyse how the Dutch government and the Dutch administrative court have responded to this issue and tried to reduce the problems to acceptable proportions by enacting a new regulation. The focus will be on the implementation of the limit values for NO2 and PM10, which are the cause of huge problems in the Netherlands. It will show that the storm in the political and legal debate has not calmed down, because the new regulation will not produce any drastically different results. Two approaches in the debate will be distinguished. The formalistic approach considers the limit values as absolute limits, to be taken into consideration by all authorities at all levels of government in the execution of all their legal tasks which could have an impact on air quality. The other, more moderate, approach recognizes that the limit values must be considered as obligations as to result, but that they must be achieved primarily by designing and executing new national programmes that have a direct influence on the sources of pollution. On this interpretation, the European Directive does not oblige all authorities to include the limit values as a consideration in all of their decisions, specifically not with regard to the area of spatial planning. The aim of this article is to discuss both approaches, and to explore which point of view can provide a way out of the deadlock-situation in which the Netherlands currently finds itself, while at the same time taking account of the EU air quality standards.

II.  European Air Quality Framework

Air quality is first and foremost a European issue. Research has shown that most national measures to combat against the most harmful effects have only a limited effect. For example, in the Netherlands, the concentration of PM10 consists to a substantial degree of  so-called “background-concentration”, caused by numerous sources within a radius of approximately twelve-hundred kilometres of the place where the concentration was first measured.

      During the 1990s the EU evaluated the existing Directives on air quality: on sulphur dioxide and particulate matter (80/779/EC), on lead (82/884/EC), on nitrogen dioxide (85/203/EC) and on ozone (92/72/EC) and it became clear that these Directives had been implemented differently in the different Member States. As a result it was decided to harmonise air quality legislation. A Framework Directive was adopted in 1996 laying down the main elements of air quality policy in the European Union[1]. The Framework Directive defines the basic principles of a common strategy. These basic principles were inserted into the Dutch Environmental Management Act[2].

      The Directive establishes and defines objectives for ambient air quality in the Community which are intended to avoid, prevent or reduce harmful effects to human health and the environment as a whole. It lays down rules to assess the ambient air quality in Member States on the basis of common methods and criteria. It also includes provisions on how to obtain adequate information on ambient air quality and ensure that it is made available to the public, as well as how to maintain ambient air quality where it is good and improve it in other cases[3]. 

       Article 7(1) requires Member States to take the necessary “measures” to ensure compliance with the limit values. Article 7(2) specifies that such “measures” must,

a.                    take into account an integrated approach to the protection of air, water and soil;

b.                    not contravene Community legislation on the protection of safety and health of workers at work;

c.                    have no significant negative effects on the environment in other Member States.

Article 7(3) requires that Member States draw up action-plans, indicating what short term measures should be taken when there is a risk of limit values being exceeded, as well as to minimise that risk and limit the duration of such occurrences. These plans may involve the suspension of activities which contribute to the limit values being exceeded, including motor-vehicle traffic.

      Article 8 is concerned with measures for zones where the levels are above the limit values. Article 8(3) requires Member States to draw up plans or programmes for situations where the standards are not met, or are about to be infringed. The competent authorities are responsible for implementing these plans and ensuring that the limit values are attained in time. It therefore seems essential that concrete measures are presented in an action plan where it is explained how the limit values are going to be attained.

The Framework Directive establishes a system for air quality aims (limit values, alert thresholds, target values) and provides mechanisms to assess air quality with regard to 13 groups of substances. These quality objectives for ambient air as defined in the Framework Directive are specified in four Daughter Directives:

-                    Directive 1999/30/EC of 22 April 1999 relating to limit values for sulphur dioxide,           nitrogen dioxide and oxides of nitrogen, particulate matter and lead in ambient air;

-                    Directive 2000/69/EC of the European Parliament and of the Council of 16 November 2000 relating to limit values for benzene and carbon monoxide in ambient air;

-                    Directive 2002/3/EC of the European Parliament and of the Council of 12 February 2002 relating to ozone in ambient air;

-                    Directive 2004/107/EC of the European Parliament and of the Council of 15 December 2004 relating to arsenic, cadmium, mercury, nickel, and polycyclic aromatic hydrocarbons in ambient air.

1.  First Daughter Directive on air quality

The first Daughter Directive was adopted in 1999 and had to be implemented by 19 July  2001. It specifies the limit values for five substances (of thirteen). One substance was new, PM10 (particulate matter), the levels of which are exceeded in the whole territory of the Netherlands. Concerns about meeting the limit values for this substance and for NO2 (nitrogen dioxide) were therefore already raised during the negotiations for this Directive by the Netherlands and some other countries. It was argued that the limit values for nitrogen dioxide and particulate matter could not realistically be achieved within the required time-frame for the entire country. This resulted in the inclusion of an article which foresaw an evaluation of the Directive in 2003, which might have lead to a proposal to approve or change the standards. The revised EU strategy and the start of the Clean Air for Europe (CAFE) program however prevented this review, with the effect that no adjustment to the first Daughter Directive has been made so far. This has led to a situation where the limit values must be respected, although in certain countries this is not feasible without disproportionate costs. As part of the CAFE program, which aims to achieve an integrated treatment of European air pollution problems, the first Daughter Directive is being reevaluated[4].

2.  Scope and margins

The core features of this Directive are limit values, margins of tolerance, alert thresholds, assessment of concentrations, reporting and information and evaluation. A limit value is 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[5]. The Directive obliges Member States to take measures necessary to ensure that the concentrations do not exceed the limit values[6]. Although the European Court of Justice has not yet ruled on the specific limit values set by the first Daughter Directive, there are a number of judgments which make clear that limit values are to be understood as a obligations to achieve specified results[7]. In the German TA Luft cases the Court considered that limit values have to be transposed into obligations of national law. If the limits are exceeded, stakeholders must have the right to appeal to the courts[8]. In the French air-cases it became clear that these limit values also create obligations for individuals[9]. In the context of water pollution, the ECJ also stressed that limit values leave no room for derogation[10]. Margins of tolerance are set because it takes time for policy measures to take effect. The limit values for PM10 came into force in 2005 and the limit values for NO2 will become effective in 2010. In the time preceding their entry into force margins of tolerance apply. These specify an annually decreasing percentage by which a limit value may be exceeded. Where concentrations exceed the limit value plus the margin of tolerance, the first Daughter Directive obliges Member States to draw up plans or programmes to improve air quality and achieve compliance with the limit values by the dates laid down[11]. For sulphur dioxide and nitrogen dioxide alert thresholds have been set[12]. These are levels beyond which there is a risk to human health from brief exposure and at which immediate steps must be taken by the Member States as laid down in the Framework Directive on air quality[13].  It also contains detailed provisions on the assessment of concentrations. A minimum number of measurement sites is specified, as well as criteria for the location of measurement sites (both macro and micro-scale criteria). In more crowded areas (agglomerations) more measurements must be performed than in other areas (zones). The method of assessment is through measurements, through calculations or a combination of measurements and calculations[14] depending on how severely the limit values are being exceeded. Calculations are only allowed if concentrations are sufficiently low. Also, public and other concerned organisations must have access to recent information[15] and Member States have an obligation to report to the Commission. The Commission has a duty to act by reporting to the European Parliament, the Council and the Member States. This may lead to a review of the annual limit values of NO2 and PM10[16]. No such review has yet taken place as a result of a changed EU strategy and the start of the Clean Air for Europe (CAFE) program. Consequently, there has been no amendment to the limit values in the first Daughter Directive so far.

III.  Transposition of the first Daughter Directive into national law – the Dutch Air Quality Order 2001

Since the first Daughter Directive was implemented in the Netherlands with the enactment of the Dutch Air Quality Order in June 2001, spatial and planning developments in the Netherlands have been delayed or brought to a complete halt due to violations of the air quality standards. The Dutch Air Quality Order 2001 implements the first Daughter Directive in a general manner. It requires all public authorities to take the limit values into account when carrying out their relevant legal functions so that the limits will be met[17]. The explanatory memorandum to the Order states that this not only applies to decision-making with regard to environmental issues, but also to spatial planning and traffic issues. Therefore it not only concerns plans affecting air quality directly but also more general spatial plans, like the development of an office block which attracts additional traffic and must thus be assessed as to the consequences of the proposed activity on PM10 and NO2 pollution. Compared with other Member States this link between the limit values in the Directive and spatial and planning decision-making is rather unique.

In principle, the limit values apply to all ambient air (except in workplaces). No distinction is made between sensitive and non-sensitive areas. The Air Quality Order, in its specification of limit values, makes no distinction between limit values to protect human health and limit values for vegetation. It has however been inferred from Annex VI of the Directive and from the guidelines issued by the Commission that no measurements or calculations are necessary in atypical situations such as immediately next to a chimney or other point emission sources. One of the most striking characteristics of the implementation of the first Daughter Directive is that the limit values are understood as absolute limit values which means that they are not open to a balancing process against other interests when decisions on permits for spatial developments are made[18]. For example, if models show that future limit values will not be met, then even a realignment of a road that will reduce air pollution is not allowed under the Order 2001. It will only be allowed if it can be shown how the decision regarding the road fits into an overall plan which will guarantee that the limit values are attained.

The Order contains very little substance on the obligation to prepare action plans as required by Article 8(3) of the Framework Directive. Where the specified alert thresholds for NO2 are being exceeded, local governments have to propose action plans to improve the local situation. Usually, this takes the form of traffic circulation plans[19]. These plans should ensure that the limit values for NO2 are attained before 2010. The secretary for Housing, Regional Development and the Environment is responsible for preparing an action plan to combat PM10 pollution[20]. The Order does not specify how these action plans should be designed. 

      Under Dutch law, citizens living in the vicinity of the planning area and non-governmental organisations have a right to object to these plans. Increasing numbers of stakeholders have seized this opportunity to challenge national and local infrastructure decision making. For example, in an attempt to reduce the number of traffic jams on motorways, the Dutch government made plans to increase the number of lanes on 33 motorways sections across the Netherlands. Some of these plans have already been approved because there were no objections, but recently three plans have been rejected by the courts following objections by stakeholders.

Application of the Air Quality Order by the Dutch court

Since  the Air Quality Order came into force in 2001, more than 40 plans proposed by the authorities have been objected to on the grounds of possible violations of air quality limit values. In about a third of the cases the highest court upheld the objections for air quality reasons[21]. These plans mainly concerned large scale infrastructure projects such as road construction or modifications, zoning plans designating land for the development of business activities or housing construction, as well as permits for industrial activities. As to the scope of the Air Quality Order the Dutch court is clear. In a case concerning a zoning plan for the reconstruction of the station island of Amsterdam, the city council of Amsterdam argued before the court that the Air Quality Order is not clear about the legal obligations to which the limit values apply. The Dutch court did not accept this argument and referred to the explanatory memorandum of the Order which states that limit values need to be considered in the exercise of any power which has consequences for air quality[22]. In another case concerning the grant of a permit for the development of a football stadium the Dutch court held expressly that local authorities should not only have to investigate the level of local PM10 concentrations, but also look into the possibilities of taking local measures. In this regard local authorities have their own responsibilities and should work to bring down emissions as far as possible[23]. However, it remains unclear when local efforts are sufficient and what is to be understood by “as far as possible”. Limit values for the protection of human health are applicable in the entire country (except workplaces). Examples where consequences on air quality were only assessed at locations where people may be exposed to them were rejected by the court[24]. The Dutch courts have consistently taken the view that a plan is allowed if – on balance – it results in an improvement[25].  In order to be able to assess this it has to be known what PM10 and NO2 concentrations occur at a specific location. However, in later rulings the Dutch court restricted the possibility of compensating negative consequences with positive ones and no longer regarded it sufficient if  a mere improvement takes place. If in a situation, limit values are being exceeded, the competent authority has to investigate whether the reduction in pollution makes a sufficient contribution to the attainment of the limit values. Additional measures should be considered which could further reduce local air pollution[26].

A quick glance at Dutch case law and it becomes clear that projects that contribute to limit values being exceeded even further than they are already, are likely to be rejected by the courts if objections are made. Although most cases were rejected by the court because the consequences for air quality had not been adequately investigated by the authorities granting consent, it is clear that it is not just a formal question of investigation. More importantly,  projects are being refused if the expected air quality does not comply with the limit values. Another interesting point to note is that the case law discussed above only concerned intended projects. Since then, new appeals have been lodged in respect of existing projects, either to reduce exceedances, or undo projects altogether.

After the effects of the application of the Air Quality Order 2001 to decision-making procedures regarding spatial plans and infrastructure projects became clear, the government proposed a new regulation  to solve the biggest problems. The first main change would have been to make a distinction between sensitive areas (houses, schools, hospitals, etc) and non-sensitive ones. Limit values would only have applied in sensitive areas. When the proposal was passed to the Council of State (the main advisory body for central government), it was so strongly criticised that it did not survive and was withdrawn. The Council of State pointed out that the text of the Directives leaves no room for such an interpretation. The Directives on air quality contain an obligation for results, leaving it up to the Member States as to how to achieve this. The Council added however, that when a project has no negative and perhaps some positive effects on the air quality, then even though limit values may already have been exceeded prior to the project, there is no reason to consider such a project an infringement of the requirements of the Directive. This, of course, does not detract from the Netherlands’ obligation to attain the  limit values within the time frame set by the Directive.

      The second main amendment that would have resulted from the proposed regulation would have been to put the responsibility for PM10 primarily in the hands of the Secretary for Housing, Regional Development and the Environment, and the Secretary for Transport and Public Works. Under the proposal local and regional authorities would have had an obligation to prescribe the best available techniques when granting permits in cases where the limit values are being exceeded. In other cases, exposure to PM10 would have had to be limited as best “as reasonably possible”. The Council of State did not agree with this perspective. It stated that according to Article 3 of the Framework Directive Member States should appoint the authorities responsible for the implementation of the Directive. Nevertheless, all national authorities have to comply with European obligations to the extent to which it is within their capabilities. 

IV.  New Air Quality Order of 2005

The Air Quality Order 2005[27] replaces the earlier one of  2001 and, at the same time, implements the second Daughter Directive[28] (for benzene and carbon monoxide in ambient air) and the EC Participation Directive[29]. The scope of the Order has remained unchanged. It imposes the requirement on public authorities to take into account the limit values in performing all relevant tasks which have consequences for air quality[30]. As under the former order, the limit values apply everywhere except workplaces[31].

Changes made by the Air Quality Order of 2001 compared with the old one include minor amendments as well as deliberate relaxations of the standards changes of the latter type are:  

-                    Firstly, concentrations that are by nature present in ambient air and not harmful to human health can be omitted from the examination of the air quality concerning PM10. A comparable provision is made for concentrations of PM10 due to natural causes.

-                    Secondly, Article 2.2 of the new Order leaves the stand still principle out of consideration which means that small deteriorations can be accepted as long as the limit values are not exceeded.

-                    Thirdly, and most importantly, Article 7.3  of the Order contains an arrangement for the compensation of negative consequences by positive effects, the so-called per balance system. Two different situations are being distinguished:

a.                  The competent authorities can exercise their competences, so long as – on balance - the concentration of a relevant substance in the ambient air has improved or at least stayed at the same level as a consequence of the decision made by the competent authorities, notwithstanding that the air quality does not satisfy the limit values;

b.                  A limited increase of the concentration of the relevant substance is permissible,  if – on balance – the air quality is improved due to the measure taken or to due to an effect caused by such a measure[32].

Contrary to the replaced Order, the Air Quality Order 2005 states in what circumstances account must be taken of the limit values. However, the given list is not exhaustive[33]. If in a particular situation effects on air quality are not to be expected, it is not necessary to give consideration to the limit values. If this is not clear initially, a global check of possible effects is needed. The explanatory memorandum also mentions that it should be checked whether a contemplated action will lead to an increased exposure to air pollution[34]. This is not required by the Framework Directive which concentrates on the air quality rather than exposure to certain air pollutants. This is surprising given that the Dutch administrative court has stressed that the limit values apply generally, i.e. independent of the question of exposure[35]. It has to be noted here that the Dutch government plans to substitute an Act on air quality for the current Air Quality Order 2005. This Act will enhance the on balance system and apply it to wider areas. A deterioration in an agglomeration would then be acceptable providing  a considerable improvement could be achieved elsewhere.

V.  Current and future debate

The aim of the Air Quality Order 2005 is to soften the social and economic consequences of the original Air Quality Order 2001 as much as possible whilst still correctly applying and implementing the EC Directives[36]. However, the political and legal debate about air quality and air quality standards will not subside even after the implementation of the new Air Quality Order 2005. The political debate will not end, because the interests at stake are fundamental to social values and daily life. There is an urgent need for the construction of infrastructure projects such as housing and roads to solve traffic congestion. On the other hand human health and the environment are threatened by air pollution. The legal debate will continue, because it is not only highly doubtful whether the amendments to the Air Quality Order 2005 and the intended Act on air quality will lead to the prescribed level of air quality, but also questionable whether these new amendments are in accordance with EC law.

The Dutch debate on air quality seems to be led by two camps, the formalists and the moderates. Both sides agree that the limit values are minimum standards and that they imply an obligation to implement them by the date set by the Directive. There is however disagreement on how and by what means this is to be achieved. The formalistic school holds  that the limit values, set by the European Directive, are absolute limits, to be taken into consideration by all authorities at all levels of government in the exercise of all their functions which could have an impact on air quality. If there is a chance that a limit value may be exceeded, decisions on all activities causing an increase of emissions of the relevant air pollutant, even if it is only a minor pollutant, should be subject to an impact assessment. This view is reflected in both the first and the second Air Quality Orders, backed up by the Council of State and national case law. It is a strict interpretation of the first Daughter Directive, according to which the limit values are fixed levels to be attained within a given period and Member States must take the measures necessary to ensure that the limit values will be met from the date they enter into force[37]. This leaves no room for any balancing against other interests. Indeed, the limit values themselves define how often they may be exceeded. The 24-hour limit value for particulate matter, for instance, may be exceeded 35 times a year. It is claimed that such a provision would be ineffective, if further infringements were regarded as acceptable on the basis of a balancing exercise of the limit values as against other interests[38]. Furthermore, Article 3 of the Framework Directive requires Members States to appoint the authorities responsible for the execution of the Directive. This implies that all national authorities must comply with European obligations to the extent to which this is within their capabilities.

      From an EC point of view the formalistic approach is a safe option: no infringement actions are to be expected from Brussels. The downside of this approach is that even projects and plans with a comparatively marginal effect on air quality have to be assessed as to their impact. This not only applies to new projects or plans, old projects or plans could also be re-opened for an impact assessment. Predictably this is going to cause serious delays in planning and spatial decision-making and may even lead to some deadlock situations. Additionally, but not unimportantly, there are the consequences for the EU’s image in the eyes of citizens and institutions, who depend on the development of large scale infrastructure projects.

The other approach is more moderate in its perspective. It argues that the limit values should be achieved, in the first place, at national level, through national measures rejecting the interpretation that  all activities which have only a limited effect on air quality must be  subject to an impact assessment. It draws attention to the lack of effectiveness of the strict interpretation. The obligation on all government bodies to take account of the limit values in exercising any tasks which could have an effect on air quality by no means guarantees that pollution levels already exceeding the limit values are reduced. Instead, therefore, the moderate approach distinguishes not only between different levels of government, but also regarding the substance of the matter. The limit values are minimum standards creating an obligation as to the result to be achieved. They are absolute, but this does not mean that the Air Quality Order should become the overriding concern in all decisions on spatial planning or infrastructure projects. In this context a distinction is made between decision-making on projects that have a direct effect on the sources of air pollution, and spatial planning projects that are not themselves direct sources of air pollution but which contribute indirectly to an increase in pollution, for example by attracting more traffic[39]. According to this view, particular attention should be given to highly polluting industrial installations and more generally to plans falling under the Integrated Pollution Prevention and Control (IPPC) Directive[40] or for which an Environmental Impact Assessment (EIA)[41] is required. The emphasis is therefore on the large scale reduction of air pollution. This also means that more substantial efforts must be made in the sense of Article 7(1) of the Framework Air Quality Directive, which is phrased very generally. Another characteristic of the moderate approach is that it looks to the potential of existing and future technologies. In general, authorities are inclined to prohibit activities and substances without investing in innovative technological alternatives. Technical solutions are often possible. For example, from a recent plan dealing with the problem of air pollution in the province of Zuid-Holland it has become clear that the reconstruction and redevelopment of industrial facilities could lead to 30 % decrease in PM10 emissions, compared with the emissions in 2000. With additional measures concerning road traffic a reduction of 50 % could even be achieved.

      In conclusion, the moderate approach is the more flexible one. Its starting point is a national level perspective to deal with the largest polluters first. An advantage of this approach is that it does not interfere with infrastructure plans which are needed and have social benefits. The disadvantage is that it takes time to conceive complex policies based on innovative technology. This time has already run out, at least for PM10, where the deadline for attaining the limit values has already passed.

VI.  Conclusion

Air quality in the Netherlands is not just an environmental and legal issue, but above all a social and political issue. Due to the lack of timely and adequate implementation policies, it was the Dutch administrative court that eventually enforced the limit values set by the first Daughter Directive. That the Dutch judges were up to their task is clear from the numerous plans and projects rejected by the court. Confronted with this result, the Dutch government vainly tried to change the tide and the secretary for Housing, Regional Development and the Environment enacted a “concept regulation” which, among others, proposed to make a distinction between sensitive and non-sensitive areas. This concept was withdrawn after strong criticism and replaced by the Air Quality Order 2005, which took effect retroactively from May 4, 2005.

Looking at the pure crisis management conducted by the Dutch government, it appears that  there has been a slight shift towards a more moderate approach. Some flexibility has been built in, which is clear from the new on balance system, from the exclusion of  sea salt as a pollutant and the deletion of the provision that contained the “stand-still” principle. It is however doubtful if this will do the trick as all administrative decisions by all authorities will still have to be assessed as to their effects on air quality. Also, from an environmental point of view scientists have already predicted that the Air Quality Order 2005, the action plans and the measures taken will not be sufficient to fulfill the European air quality standards

The legal boundaries have been stretched. Although the European Court of Justice has not ruled on the air quality limit values, it can be concluded from earlier case law that the Court interpreters them as a strict obligation to be complied with by Member States. The solution to the current problems therefore has to come from a policy change in Brussels, which takes into account the different characteristics and circumstances in the Member States. For example, for the Netherlands, the ability to comply with the uniformly set limit values is limited by ‘structural’ realities, like a high population density, a particular geography (the entire country is exposed to the influence of the sea) and the fact that the Netherlands has become a transportation centre. These special conditions make it very difficult to implement the currently uniform Directives on air quality. In the end, the solution to air quality problems in the Netherlands, as  in the rest of Europe, has to be sought in the European political arena.