Clean Air – Cities and Societies

Health impacts of air pollution is currently the main driving force for action towards reducing emissions. As three quarters of the EU population live in cities, and cities are air pollution hot-spots, urban citizens are particularly exposed to and affected by air pollution. It is therefore especially interesting to discuss how the Nordic cooperation can improve air quality in cities.

There are many implementation challenges with the current and the revised EU Ambient Air Quality Directive in the Nordic countries. The Danish air quality monitoring program provides experiences useful for discussions on how to implement the revised AAQD. These experiences are likely common for most Nordic countries.

The revised EU AAQD is nearly fully adopted

The Nordic Air Pollution workshop on took place on October 7–8, 2024, the revised AAQD was adopted on October 14, 2024.

and the requirements for monitoring must likely have to be followed from 1 January 2027. This implies also that the supersites must be started up with measurements of all the new air pollutants and that the new requirements for modelling will have to be incorporated.

In addition to new requirements for monitoring and supersites, there are also new air quality limit values as well as requirements on Average Exposure Reduction Targets. The new limit values and target values are entering into force from 2030 as well as the requirements on the Average Exposure Reduction Target. Denmark is already in compliance with the new limit values, and most likely fulfil the requirements on the Average Exposure Reduction Target in 2030.

There are some aspects that from a scientific and technical viewpoint seems to be inadequate when compared to the aim of the revised directive. In the context of this workshop, the following four questions are of special interest:

Air pollution is generally estimated to be the single largest environmental health risk, both globally and in the Nordic countries. The majority of health burden and excess deaths are usually attributed to long-term exposure to fine particulate matter (PM_2.5). PM_2.5 is estimated to annually cause 5–9 million excess deaths globally, around half a million in Europe, and a few thousand in each Nordic country. There is clearly “evidence enough for actions” regarding health effects of ambient air pollution even at low exposure levels, and a wide consensus that the burden of disease is large. The WHO 2021 Air Quality Guidelines (AQG) are in the Nordic countries mostly exceeded in the larger cities where road traffic is intense and in the southern parts of the Nordics. For the burden of disease due to air pollution it is most important to reduce exposure levels where the population density is the highest. Reductions even below the WHO 2021 AQG are expected to yield further health benefits.

Examples of issues left to solve are:

The large differences in burden of disease estimations. For example, Gustafsson 2022 estimated 6,740 annual deaths due to air pollution in Sweden, compared to 911 deaths in 2021 due to PM_2.5 in the Global Burden of Disease (GBD) estimation 2021. For solid fuel use/wood burning Gustafsson et al estimated 708 deaths in 2019, compared with 0.24 for indoor exposure due to solid fuel use in 2021 in the GBD (somewhat different exposure definitions). GBD estimates for the other Nordic countries are mostly comparable, but with some interesting differences. A discussion on the best methods to estimate burden of disease and how to communicate the results is warranted. Strengthened evidence for “new” health outcomes might be needed to include in burden of disease and cost estimations, but mortality generally represents the main burden.

The remaining knowledge deficiencies regarding which particle constituents​/​sources that incur the most health effects. To solve this knowledge gap, more measurements of UFP and BC are required for the high-resolution exposure modelling of long-term exposure that is needed for the epidemiological studies of the health effects of these exposures, and to what extent these differ from those of PM_2.5 mass. The relative effects of local emissions compared to long-range-transported particles also need to be elucidated. More knowledge on the toxicity of non-exhaust emissions from traffic (i.e. road, breaks and tyre wear) is also important, since the relative contribution of these components in total PM_2.5 concentrations is increasing. Human chamber studies would be valuable to evaluate the relative toxicity, especially regarding cardiovascular effects.

The question on whether control of air pollution levels is more effective than a focus on “healthy cities”? Preventive efforts are likely to yield benefits also through reduced co-exposures, and especially increased physically active transport. Focus needs to be both on “low-hanging fruits”, such as the dirtiest vehicles and wood stoves, and on the most common emission sources.

The balance between local preventive efforts versus international legislation? The burden of disease due to air pollution in the Nordic countries would also decrease substantially if emissions are reduced in nearby countries. Rapid introduction of the WHO 2021 AQG into EU legislation is thus a priority. Additional limits on locally emitted air pollutants should however also be considered. Local preventive measures should especially consider sensitive groups, such as children and the elderly.

Health effects as a consequence of air pollution levels amount to several million premature deaths worldwide, also in Europe, despite decreases in air pollution concentrations over the last decades. Mortality constitutes the biggest share financially and gets the most attention, but effects on morbidity also contribute significantly to reduced welfare and socioeconomic costs.

With the integrated assessment modelling done with the EVA system (Economic Valuation of Air pollution), it is possible to follow the pathway from emissions to socio-economic costs through emission inventories, air pollution modelling, population exposure and response and valuation of health effects.

An example of a current EU project that applies the EVA system for generation of policy input is the MARCHES project, focusing on general and national characteristics of all the European countries with respect to health effects.

There are several more projects that have utilised the EVA system. The NordicWelfAir project showed among many other things, how detailed emission data based on national knowledge and approaches play a crucial role in health impact assessments. Several previous and ongoing NMR funded projects have focused on the impact of different emission sectors (e.g. residential wood combustion - NordSmoke, shipping – Epitome, etc.) on human health, and the understanding of the similarities and differences between the Nordic countries has been greatly advanced.

Still, these recent projects have also revealed the need for continued research within all aspects of the impact-pathway chain. For the Nordic region this is especially related to:

Such research could directly support improved policy actions in the Nordic countries and enable cost effective protection of human health.

Discussions focused on economic valuation of health impacts, health-effect studies, the need to maintain air quality monitoring also in “low-pollution” areas, co-benefits of improved city-planning (e.g. air quality, noise, mobility, green areas), and on a zero-pollution target for the Nordic.

The Nordic cooperation on air quality should aim to:

Ensure continued air quality monitoring even when concentrations of air pollutants are below WHO 2021 guideline values. The air quality in the Nordic countries have improved over the last decades and is now amongst the best in the world. It can be expected that many Nordic cities will soon have air pollution levels lower than the WHO 2021 AQG for many pollutants. When this happens, there is commonly a push from policymakers to save expenditures by ending regular monitoring. However, there are still fundamental scientific challenges related to air pollution and health, such as the separate effect of UFP and BC on health, and the health effects of air pollutants in low-exposure environments (i.e. areas with air cleaner than WHO AQG). In order to get more solid scientific knowledge about these questions, it is essential to continue monitoring also in areas where the air quality is better than WHO AQG. It should be remembered that there still are substantial health effects even at levels below the WHO 2021 guidelines. Furthermore, population growth and economic development has always so far been pushing air pollution levels up. So even if the Nordics in the near future can reach air quality levels below WHO AQG, it is important to maintain monitoring to ensure that the trend isn’t reversed. It must be recalled that increasing pollution levels have large socio-economic costs.

Ensure that Nordic countries take leadership on setting ambitious (zero) emission targets for air pollution. As explained above, the Nordic countries have a rather unique position with respect to air quality. Whilst some EU countries try to water down increased EU/European ambitions with respect to air quality, countries in other regions of the world are looking for inspirational examples of how to allow cities and countries to grow, whilst at the same time reduce emissions of air pollution and improving air quality. Now the Nordic countries have an opportunity to show leadership with respect to air quality.

Review existing Nordic evidence on health effects in low-pollution environments. The Nordic countries have a fortunate combination of good-quality population data, high-quality exposure assessments and low pollution environments. Therefore, there is now a good opportunity to help Nordic policy making and policy decision support modelling by reviewing Nordic air pollution health studies. It is currently expected that the relative impact of a change in air quality is larger per microgramme in low-pollution environments than in high-pollution environments, if this expectation can be confirmed for the Nordic setting, it would likely change the advice from Nordic policy support modelling to policy makers.

Maximise Nordic benefits of current EU projects on air pollution and health. In a recent EU Horizon call focused on environmental stressors and human health, Nordic research groups had a very good success rate. During 2023-2026, several Nordic research bodies are in a leadership position of the research projects BestCost, Marches, and VALESOR, which are coordinated under the Meteor cluster.

https://meteor-research.eu/

These projects study air pollution effects on health and its socio-economic consequences, which is of high relevance for Nordic decision-making related to air pollution and air quality. The Nordic Council of Ministers should grasp this opportunity to arrange build-on activities and knowledge dissemination workshops with these projects so as to maximise Nordic uptake of the knowledge produced.

Produce Nordic guidelines for city development respecting the citizens right to clean air. The ongoing urbanisation in the Nordics demands continued expansion and/or densification of cities. These developments can take place in many ways, and not all of them are beneficial for air quality. However, there are inspirational Nordic examples of how to develop cities so as to enable good air quality even in cities. A prominent example being the action taken by the city of Odense in Denmark. Production and dissemination of such Nordic guidelines to urban planners will help highlight the prerequisites for city planning enabling good air quality.

Clarify the economic value of air quality-related ecosystem services in cities. Many modern city planners utilize and highlight the importance of green areas in cities, sometimes with reference to their positive effect on air quality. However, this effect is contested, and most likely not as effective as specific emission reduction measures. But ecosystem services in cities have many benefits, not only for air quality. So, in order to help decision-making, it is important to show the economic benefits of various ecosystem services in cities, and also highlight which of the services that have best effects on Nordic air quality.

The discussions under the theme ‘Clean Air – Cities and societies’ were mainly aimed at developments in EU and in particular in the Nordic countries. However, many of the projects and initiatives presented above are applicable to several (other) arenas, such as the Air Convention (including FICAP) and various city networks.