Impacts of air pollution

Many natural and semi-natural ecosystems in Europe are exposed to high atmospheric nitrogen deposition and resulting eutrophication. A slight decrease of areas at risk can be observed during the last 20 years. However, nitrogen deposition remains problematic at present and in the future under the current legislative plan.

Eutrophication is a serious threat to European ecosystems and is caused by the deposition of air pollutants containing reactive nitrogen. The processes alter the availability of nitrogen as a nutrient for plants. As a result of altered nutrient availability, species composition may change, and ecosystem integrity may be threatened. These changes carry the risk that more nitrogen loving ecosystems may prevail and outcompete those ecosystems that are adapted to nutrient poor conditions. This leads to the loss of ecosystem diversity as an integral part of overall biodiversity. To be able to quantitatively assess the risks for ecosystems from those changes, the concept of Critical Loads was developed to estimate the amount of deposition that does not lead to effects as mentioned above and is therefore considered acceptable. As soon as the estimated deposition exceeds the Critical Loads, ecosystems are considered to be at risk.

Ecosystem specific Critical Loads for Nitrogen can be derived from observations and experiments and related dose-response functions of nitrogen affecting the state of an ecosystem. Such Critical Loads are called Empirical Critical Loads. Other ways to determine Critical Loads for Nitrogen are modelled based calculations.

For further information please visit CCE | Umweltbundesamt or check the information in the latest CCE Status Reports | Umweltbundesamt. You might also consult the latest report on Empirical Critical Loads Review and revision of empirical critical loads of nitrogen for Europe | Umweltbundesamt or the CCE - Manual | Umweltbundesamt External link, opens in new window..

Much progress has been made in establishing critical levels of ozone for vegetation, above which adverse effects could be expected. Several Convention workshops have been held in which the critical levels of ozone for crops, (semi-)natural vegetation and forest trees were established.

Two main types of critical levels have been developed:

• Concentration-based critical levels that are based on the concentration of ozone in the air immediately above the plant.
• Flux-based critical levels that are based on the amount of ozone entering the leaves of plants. Ozone fluxes are calculated using knowledge of how climate, soil factors and plant factors influence the opening and closing of the stomatal pores on the leaf surface.
  

In addition, methods have been developed for mapping the risk of damage to a generic crop and two generic tree species using a simplified flux model that can be applied within integrated assessment modelling. Ozone critical levels, their scientific basis and generic flux -based risk assessments are described in detail in Chapter 3 of the LRTAP Convention Modelling and Mapping Manual External link, opens in new window..

The ICP Vegetation coordination centre and participants are also working with new crops and vegetation types at their experimental sites (e.g. UKCEH solardome site External link, opens in new window. in Bangor, North Wales) to gather data to develop additional flux response relationships, for example, for sweet potato.

The ICP Materials work includes the assessment of the damage of air pollution to selected UNESCO heritage sites. Materials used in cultural objects are still subjected to corrosion and soiling from sources within the cities (such as nitric oxide and particulate matter) where most of the cultural heritage is situated.

The latest trends show a modest decrease of NO2 and PM10 concentrations at all the investigated UNESCO sites. Despite this decrease, pollution still threatens our cultural heritage and consequently increases the economic costs of maintenance. Mitigation strategies for local sources such as traffic reduction policies need to be implemented to ensure the protection of our heritage. The latest report can be accessed through the ICP Materials website. External link, opens in new window.
Corrosion and soiling not only impact our cultural heritage, but also degrade and damage our infrastructure, in particular our bridges and tunnels that are especially exposed to particle pollution. The effect of particulate matter has shown no declining trend in regards of corrosion and soiling. Particles often attract and retain moisture which in turn increases the corrosion rate of metallic materials, decreasing the lifetime of our infrastructure. Particles also enhance the effects of soiling by increasing the appearance of dirtiness and reducing the ability of objects to reflect light. The costs of maintenance, repairs and renovations are thus negatively impacted by the effect of particulate matter. More on the subject can be read in the “Air & Environment: Particles destroy and pollute External link, opens in new window.” published by the Swedish Environmental Protection Agency.