On 4 March 2021, the Court of Justice of the European Union (“the CJEU”) handed down judgment in Commission v UK (Limit Values – Nitrogen Dioxide) [2021] EUECJ C-664/18. The CJEU declared that the UK had breached certain of its obligations under Directive 2008/50 on ambient air quality and cleaner air for Europe, which entered into force on 11 June 2008 (“the Directive”). To read the judgment in full, please click here.

On 15 March 2021, Bath became the first English city outside London to launch a Clean Air Zone (“CAZ”). If the CJEU’s judgment in Commission v UK is anything to go by, the introduction of a CAZ outside London has been a long time coming – too long, the CJEU would say.

Important Definitions

Under Article 2 of the Directive, “limit value” means 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”. A “margin of tolerance” may be added to a limit value, which is “the percentage of the limit value by which that value may be exceeded subject to the conditions laid down in this directive”.

Two Complaints

The European Commission made two primary complaints relating to excessive nitrogen dioxide (NO2) in the air. First, the European Commission submitted that the UK had systematically and persistently, since 1 January 2010, breached Article 13(1) of the Directive by exceeding the annual limit value for NO2 in sixteen zones of the UK including Greater London, the East Midlands, the South East and Glasgow (“the Sixteen Zones”) and by exceeding the hourly limit value for NO2 in Greater London.

Secondly, the European Commission submitted that the UK had, since 11 June 2010, failed to comply with Article 23(1) of the Directive in that it failed to ensure the period of exceedance of the NO2 limit values was kept as short as possible. 

The First Complaint: Article 13(1) (Annual and Hourly Limit Values)

The CJEU upheld the European Commission’s first complaint.

In the annual air quality reports submitted by the UK (pursuant to Article 27 of the Directive), from 2010 to 2017 inclusive, the annual limit value for NO2 was exceeded in the Sixteen Zones and the hourly limit value was exceeded in the Greater London urban area more than 18 times per calendar year, which is the number of days for which exceedance is permitted under the Directive.

The CJEU’s findings at [56] were damning:

As regards, in particular, the exceedances of the annual limit value, the data show that, between the years 2010 and 2016 in all those [sixteen] zones, the stated values regularly exceeded between 25% and 75% of the limit value laid down by Directive 2008/50. In some years, the amount by which the value was exceeded was more than three times higher than the limit value laid down by Directive 2008/50 (see the zone UK0001 (Greater London urban area) for the years 2013 to 2015).

The CJEU therefore found at [58] that the exceedances in those Sixteen Zones “must be regarded as persistent and systematic“.

The UK argued that it was not the only Member State to have declared breaches of Article 13 of the Directive. This was given short shrift by the CJEU: the failure of other Member States does not exonerate the UK. The UK also argued that its breaches of Article 13 were largely due to the fact that vehicle emission standards fixed at EU level had not achieved the anticipated reductions in NO2 emissions – which was exacerbated, the UK said, by a German car manufacturer that had admitted to cheating emissions tests. The UK also argued that non-compliance with limit values associated with diesel transport was a ‘European-wide’ challenge. To this, the CJEU said that motor vehicles are not the only cause of NO2 emissions or of PM10 (particulate matter akin to floating dust, the levels of which are also circumscribed by Article 13). The CJEU also said that EU rules on motor vehicles cannot exempt Member States from their obligation to comply with limit values.

The Second Complaint: Article 23(1) (Period of Exceedance)

The CJEU also upheld the European Commission’s second complaint.

Under Article 23(1) of the Directive, since 11 June 2010, where in a given zone the levels of pollutants in ambient air exceed any limit value or target value, plus any relevant margin of tolerance, Member States shall ensure that air quality plans are established for that zone in order to achieve the limit value or target value. If the limit value is exceeded and the attainment deadline for the limit value (set out in the annexes to the Directive) has already expired, then the air quality plan must set out measures to keep the exceedance period as short as possible.

The CJEU held that there is a clear link between the obligation to keep to the limit values (Article 13) and the obligation to establish air quality plans to achieve the limit values when they have been exceeded (Article 23). Where limit values have been exceeded by a certain magnitude and duration, this is evidence that the Member State has not taken the measures it is required to take under Article 23.

Exceeding the limit values for NO2 is not in itself sufficient, though, to establish that the Member State has breached Article 23(1) on keeping exceedance periods as short as possible. In deciding whether a Member State has breached that obligation, the CJEU adopts a case-by-case analysis.

Here, the CJEU noted that the UK did adopt, over the course of 2015, air quality plans and various measures intended to improve air quality in the zones in question.

The European Commission criticised those 2015 plans for, inter alia, failing ambitiously to address the main sources of NO2 emissions, in particular from the transport sector; it said that traffic volumes, fuels used and driving behaviour should all have been addressed with more ambition and urgency in the air quality plans. The European Commission gave examples such as restricting access to high polluting vehicles in certain areas (i.e. CAZs) or promoting hybrid, electric or other ‘zero emission’ vehicles.

The CJEU ruled that the UK had “manifestly failed to adopt in good time appropriate measures” to keep as short as possible the exceedance periods in the zones concerned. It criticised the 2015 air quality plans for a number of reasons. For example, they failed to provide an estimate of the improvement of air quality planned, which was information “of fundamental importance”. The description of the measures in the 2015 plans were “often insufficiently detailed, summary or vague“. Some of the measures in the 2015 plans were not legally binding or did not directly relate to NO2 emissions, such as tree planting or the use of solar energy. The CJEU noted that the time periods for attainment in the UK’s 2015 – and 2017 – plans were of “considerable duration” into the future, which was a factor pointing to a Member State not adopting “appropriate measures in good time” to ensure that the NO2 exceedance period is as short as possible.

Wider Context

This decision comes against a background of long-running litigation in relation to air quality brought against the Government by ClientEarth, a non-governmental organisation that focuses on using the law to ensure or bring about environmental protection. That litigation began as long ago as 2011 and reached the Supreme Court in R (ClientEarth) v Secretary of State for the Environment, Food and Rural Affairs [2013] 2 All ER 928.  A reference was made to the CJEU before a further hearing in the Supreme Court [2015] 4 All ER 724. As Lord Carnwath observed at [1]:

These proceedings arise out of the admitted and continuing failure by the United Kingdom since 2010 to secure compliance in certain zones with the limits for nitrogen dioxide levels set by European law.

The Supreme Court quashed the Government’s air quality plans for London and other urban areas and ordered production of new and improved plans by December 2015. The case was remitted to the Administrative Court to supervise the production of the new plans. In due course, the Administrative Court declared the Government’s 2015 Air Quality Plan (“AQP”) unlawful, requiring further steps to meet the UK’s obligation to reduce NO2 concentrations across the country: [2017] PTSR 203. At [95], Garnham J concluded that Article 23 required the Secretary of State to “aim to achieve compliance by the soonest date possible” and to “choose a route to that objective which reduces exposure as quickly as possible, and that she must take steps which mean meeting the value limits is not just possible, but likely“.

The matter came back before Garnham J in the Administrative Court in 2018, where it was held that the Government’s 2017 AQP was “seriously flawed” by applying a benchmark to the relevant areas which would be “pointless“: [2018] Env LR 21 at [71], [87]. It was reaffirmed at [74] that the Secretary of State “must ensure that, in each of the 45 areas, steps are taken to achieve compliance as soon as possible, by the quickest route possible and by a means that makes that outcome likely” and, at [85], that he must also design a “mechanism for enforcing the local plan“.

Human Impact

The human effect of air quality breaches was recently highlighted by the inquest into the death of Ella Adoo Kissi-Debrah. Ella died in February 2013 of acute respiratory failure caused by severe asthma. Air pollution was held to have been “a significant contributory factor to both the induction and exacerbations of her asthma”. For more detail, please see Thomas Herbert’s blog here.

More widely, a 2018 report led by King’s College London and published by the Government’s Committee on the Medical Effects of Air Pollutants estimated that “the mortality burden of the air pollution mixture (based on associations with PM2.5 and NO2) … in the UK is an effect equivalent to 28,000 to 36,000 deaths at typical ages, associated with a loss of 328,000 – 416,000 life years“: see paragraph 9.3.

Where Next?

As noted above, Bath has become the first city outside of London to implement a CAZ. It may be that others will follow.

It is unclear if enforcement action will be taken by the European Commission or the CJEU if the UK fails to reduce levels of pollution within a reasonable period, or indeed whether such action would be effective now that the UK is no longer a member of the European Union.

What is clear, however, is that this is an issue – both domestically and internationally – that is not going away. Whether it comes from the European Commission, ClientEarth, an inquest or elsewhere, pressure is likely to continue to mount on national and local government to reduce air pollution levels.

Patrick Limb KC and Thomas Herbert explored the above issues, and others, in their March 2021 webinar on ‘Clean Air and Tort Law‘. To view the webinar recording, please click here.