A milestone for cleaner air

The European Union has now adopted the Ambient Air Quality Directive, which is a move closer to the WHO standards. Though some steps remain before it is fully aligned.

On October 14, EU Environment Ministers confirmed adoption of a revised Ambient Air Quality Directive for the European Union. This process was the long culmination of the efforts of academia, researchers, civil society and some Member States and industries to move closer to the 2021 revision of the World Health Organization Air Quality Guidelines. While it is a proud day for Europe, and all of those who fought hard to bring this alignment closer, and represents a significant win for health and environment, gaps do remain between the proven science of air pollution, and the Directive. There is room for improvement, but that isn’t to take away from the great win for Europe that has been seen, a very positive outcome of a very long procedure to achieve cleaner air.

Since the publication of the updated World Health Organization (WHO) Air Quality Guidelines in 2021, many have been pushing for the European Union to update its antiquated key Directive on air quality; the Ambient Air Quality Directive (AAQD). The previous legislation was published in 2008, making it 16 years old at the publishing of the new Directive. In those 16 years, the science, knowledge, technology and assessment and modelling of air pollution have made incredible strides, and incredible strides require legislation to keep up. A pillar principle of health-protecting legislation should be that if the science is known, then policy needs to align with the science to protect health and environment; anything less represents a form of negligence. An ignoring of the science of people’s health in favour of other factors.

These factors are well known, and were present during the process. Industry came in strong, with many pulling the standard lines that more stringent regulation will negatively impact jobs, productivity and the economy. This line was reinforced by some Member States, often states with large industrial and production sectors. Some did actively go so far to question the science, another age-old industry playbook move. All the while the science not only consistently supports assessments of the grave impact on health of environment of air pollution, Europe’s biggest environmental health hazard, but also while the EU’s own assessments show a many times net-benefit of tackling air pollution.

The Impact Assessment used by the EU shows that even with the most-costly, most-stringent application of limit values, in line with the science, the economic gain would be six times that of the money spent, even at a self-described “conservative estimate” by the EU [1]. Coincidentally, the positive effect on GDP is seen at this highest level of ambition, with a 0.44% increase in European GDP predicted with this highest level of scientific alignment [1]. This stands contrary to the industry line of negative economic effects, and enough is known about air pollution science to show that the negative impacts of air pollution are not just in cost, but in disease, illness, loss labour capacity and infrastructure damage, just to name a few. And of all of this not even considering the interlinkages between air pollution and climate change, including shared emission sources, climate effects and vulnerability of populations.

So where did we land this year? Well, after years of push and pull, we ended up with a fairly positive leap in the right direction. The EU voted to increase the level of ambition and alignment with science, and push for tighter legislation and limits. Granted, it wasn’t the full alignment hoped for by many, but it should be acknowledged that it is a large, positive step, that came after much challenge. And the EU, and all those who fought hard for a stringent AAQD should be proud of how far this legislation has come. There has been a significant update, and not only in terms of limit values, but also sampling, access to justice and revision mechanisms.

In terms of limit values, we saw reductions in some of the most important pollutants. Crucially, PM_2.5 limit values have been reduced from an annual average of 25 to 10µg/m³. For PM_2.5, the WHO states the “safe” limit should be below 5µg/m³. PM₁₀ has been reduced from an annual average of 40 to 20µg/m³. The WHO guideline is 15µg/m³. For NO₂, the annual average has been reduced from 40 to 20 µg/m³; the WHO guideline is 10µg/m³ (Figure 1). These annual limit values are also complemented by a range of other limits for daily and hourly averages (Table 1), but also the number of allowed exceedances. The PM10 daily exceedance allowance drops from 35 times to 45 to 18 times per calendar year. The number of times the hourly rates of NO₂ and SO₂ was reduced from 18 times per calendar year to three. Carbon monoxide, PM_2.5 and NO₂ now have short-time (24 hour) limit values, lacking in the previous Directive.

In terms of other pollutants covered in the AAQD, benzene limit values have been reduced from 5 to 3.4 µg/m³ in the new directive. Arsenic, Cadmium, Nickel, and Benso(a)pyrene levels have stayed the same, but are now enforceable limit values, instead of the previous status as target values. Ozone has missed out in the new Directive; which remains at a target level with an 8-hour mean of 120µg/m³, not a limit value, which is much less enforceable. The decision around ozone was partly because it was argued that ozone, despite its crucial role in the health and environment effects of air pollution, is too complex with too many natural and extra-regional factors involved in the chemical chain of formation. This has not hindered other countries, such as Canada and US, to set ozone ambient air quality standards, however.
The Directive outlines how these new values are to be met. Firstly, these new values are to be met before January 1, 2030, with allowances for Member States around emission from nature sources and winter-sanding and salting. Member States can also request a postponement until 2040 in areas with specific climate or geographic challenges, including if the reductions can only be reached with significant impact on domestic heating systems. Postponement can be made until 2035, with a possible 2 years extension, if modelling shows that the limit values can not be achieved by the deadline, but this must be accompanied by a roadmap and report that the exceedance will be kept as short as possible, and that the limit value is to be met by the end of the postponement period at the latest. Any Member States risking exceedance by 2030 must establish a roadmap ahead of the deadline of December 31, 2028, after which, Member States must establish air quality plans when a limit value has been exceeded.
This Directive also has stipulated other changes to enhance power and enforcement of the Directive to reach these lowered values. Short-term action plans will be established when the alert threshold has been exceeded and there is potential to reduce the pollutants during a pollution episode, or prolonged exceedance and these can include emergency measures, such as suspending construction work or vehicle use to reduce the immediate health risks related to pollution. Also included is monitoring by local and national authorities of air quality through “supersites”, which might include emerging pollutants of concern, such as ultrafine particles and black carbon [2]. The Directive also mandates a review of air quality standards by 2030 and every five years from then, to allow assessment of alignment with the latest scientific evidence and WHO guidelines as needed. In addition, Member States have to ensure that citizens are entitled to claim and obtain compensation where damage to their health has occurred because of an intentional or negligent violation of certain provisions of the directive. But the prerequisite for this is quite strict.

The updated AAQD provides a great leap forward for air pollution control in Europe, and represents a world-leading legislative effort to reduce the health and environmental impact of air pollution, and reap the vast benefits of cleaner air. However, the science continues to push forward, even in the years since 2021, with research showing that PM_2.5 continues to impact health under the level of 5µg/m³. The European Environment Agency has modelled this and has shown that in addition to the 253,000 deaths attributable to pollution over the WHO guideline each year in the EU-27, an additional 179,000 deaths are added to this number when considering exposures under this threshold. This leads to a total of 432,000 deaths attributable to PM_2.5 pollution in the EU-27, a large percentage of which is under the guideline [3].
The consistent line from researchers in the field is that no level of air pollution is safe. We are hoping that policy continues to push forward with this in mind also, towards a zero pollution future.

Table 1. Changes to annual, daily and hourly limit values for key pollutants.

Figure 1. Reductions of key pollutants between the 2008 and 2024 Ambient Air Quality Directives (AAQD), in comparison to the WHO recommendation, and zero pollution.

References:
[1] European Commission. “Impact Assessment Report Part 1.” European Commission. 2022.
[2] Meteor. How science can support a swift, health-based implementation of the new EU clean air law: A METEOR Cluster science-to-policy briefing. Meteor: Methods for Assessing Health-related Costs of Environmental Stressors. 2024.
[3] EEA. Harm to human health from air pollution in Europe: burden of disease 2023. European Environment Agency. 2023.
[4] HEAL. Press release: Health groups welcome the confirmation of revised EU air quality law: milestone for public health. Health and Environment Alliance. 2024.