Emissions of several atmospheric pollutants – sulphur oxide (SOx), nitrogen oxide (NOx) and non-methane volatile organic compounds (NMVOC) – have been reduced in Luxembourg over the last 10 years. Emissions of NMVOC should meet the reduction target set by the EU Directive on National Emission Ceilings (NEC) for 2010. Sulphur dioxide (SO₂) concentrations have been kept well below the authorised limit for the protection of human health. Similarly, the limit for fine breathable particles (PM₁₀) has never been exceeded. However, limits for nitrogen dioxide (NO₂) are being exceeded in the city of Luxembourg, primarily because of automobile traffic. Luxembourg is unlikely to meet the target for NOx emissions set by the NEC Directive and measures will have to be taken to control the main sources of NOx (district heating, industry and transportation) which is a precursor of ozone. These measures will help prevent the formation of ozone which is particularly important since concentrations of ground-level ozone are regularly above the pre-alert threshold for the protection of human health at several sites. The country has yet to come up with a regional ozone plan. Bio-surveillance programmes for dioxins and furans (PCDD/F) in the vicinity of steel plants indicate that certain health standards are sometimes not observed.

The state and impacts of air pollutants, along with drivers and pressures, can be examined in two ways: firstly with regard to air quality and secondly with regard to quantities emitted.

Air quality

Luxembourg has established three air quality monitoring zones: the Canton of Luxembourg (30 % of the population), which includes the capital city and its immediate surroundings; the Canton of Esch-sur-Alzette (30 % of the population), which is highly industrialised; and a zone consisting of the remaining 10 cantons, which are largely rural (40 % of the population).

Concentrations of sulphur dioxide (SO₂) have remained well below the limits for the protection of both human health and ecosystems [Figure 1]. Concentrations of carbon monoxide (CO) also comply with the limits for the protection of human health [Figure 2], as do those of benzene and lead (mostly found in suspended dust particles).

In the case of nitrogen dioxide (NO₂), a limit value of 40 μg/m³ (annual average) has been set for 2010, however the city of Luxembourg has been breaching this limit. Moreover, the city has exceeded the hourly average of 200 μg/m³ on a number of occasions since 2000, although never beyond the 18 exceedances allowed per year. The main cause is automobile traffic and, due to the ever-increasing volume of traffic to and through the city, the introduction of catalytic converters and the renewal of the automobile fleet have not had the desired impact [Figure 3]. In rural areas, the limit of 30 μg/m³ (annual average) for the protection of ecosystems has been respected [Figure 4].

Levels of fine particulate matter (PM₁₀) do not seem to pose a major problem to human health. Over the last 10 years, the limit of 40 μg/m3 (annual average) has never been exceeded. The annual averages in the cities of Luxembourg and Esch-sur-Alzette have dropped from 30 μg/m³ in the 1990s to 25 μg/m³ in recent years. Exceedances of the 50 μg/m3 daily average in these two monitoring zones have also declined since the 1990s, and are now below the 35 exceedances allowed per year [Figure 5].

Over the past decade, in urban and rural areas alike, there have been between 10 and 30 occasions every summer when ground-level ozone concentrations have exceeded the summer pre-alert threshold of 160 μg/m³ (human health threshold measured hourly), and up to 10 exceedances of the reporting threshold (180 μg/m³). However, the alert threshold (one-hour average concentrations above 240 μg/m3 over a period of at least three consecutive hours) has not been exceeded [Figure 6].

Figure 2 - CO emission measurements: 1989-2009

Source: Ministry of Sustainable Development and Infrastructure - Environment Agency: Annual Activity Report, p. 178-179.
Note: The 3 stations are Luxembourg city centre (LC), Luxembourg-Bonnevoie (LB) and Esch/Alzette (ES).

Figure 3 - NO2 emission measurements: 1995-2009

Source: Ministry of Sustainable Development and Infrastructure - Environment Agency: Annual Activity Report, p. 161.

Figure 4 - NOx emission measurements: 1995-2009

Source: Ministry of Sustainable Development and Infrastructure - Environment Agency: Annual Activity Report, p. 173-175.

Figure 5 - PM10 emission measurements: 1995-2009

Source: Ministry of Sustainable Development and Infrastructure - Environment Agency: Annual Activity Report, p. 175-177.

Air pollutant emissions

Since falling sharply (–80 %) during the 1990s as a result of the shift from blast furnaces to electrical arc furnaces in the steel industry – see climate change mitigation common environmental theme – SOx emissions in Luxembourg have continued to decline (–12 %) during the first decade of the 21^st century. The rising market share of low-sulphur fuels, encouraged by tax incentives, has played an important role here.

NOx emissions also fell during the 1990s (–25 %), reflecting efforts to curb industrial combustion and, to a lesser extent, mobile sources. NOx emissions from these two sources have continued on a downward trajectory since 2000. Nevertheless, Luxembourg is likely to fall short of the 52 % reduction objective for the period 1990-2010 set by the Gothenburg Protocol, which is equivalent to the ceiling in the NEC Directive (2001/81/EC). In order to comply with the ceiling one important factor is the reduction of emissions from the glass industry, whose operating permit is to be reviewed to enforce the introduction of the appropriate technology to reduce NOx emissions.

NMVOC emissions fell significantly in the 1990s and have declined further since 2000, reflecting continued progress with mobile sources. Luxembourg’s NMVOC emissions are likely to meet the NEC Directive target for 2010. There are many kinds of NMVOC, and many different emission sources. The expected improvements will mainly come from a reduction in the use of organic solvents in paints and varnishes (Directive 2004/42/EC) or from vapour recovery at service stations (Directive 1994/63/EC). As of 2008, all installations using organic solvents must respect limits on emissions (Directive 1999/13/EC) [Figure 7].

The Luxembourg steelmaking industry is represented by three electric-arc steel mills, located close to one another in an urban setting (Esch-Schifflange, Esch-Belval and Differdange). If the conventional impact zone is taken as a three-kilometre radius, 55 000 people, or 12 % of the national population, are affected. Emissions of dioxins and furans (PCDD/F) from the steel mills are regularly checked by licensed agencies. In order to supervise operating conditions more closely, the Environment Administration has also been taking supplementary measurements. Over the course of the last 5 years, PCDD/F emissions have been below the 0.1 ng/m³ limit, although there was one exceedance in 2009 (Differdange). The PCDD/F accumulation in leafy vegetable crops is measured by a network of monitoring points in the immediate vicinity of the steel mills. These measurements indicate that the preventive health threshold is still being exceeded on occasion, particularly at Schifflange. In a study of PCDD/F concentrations in soils, a significant %age of soil samples were not meeting the standards for an unrestricted farming use (30 % in 1993/94 and 25 % in 2006).

Figure 7 - Air pollutant emissions according to the NEC Directive: 1990-2010

Source: Ministry of Sustainable Development and Infrastructure - Environment Agency. For background data, click here.
Note: new calculation method from 2007 onwards: break in time series.

Presented together with the 'State and Impacts'.

Although emissions of SO₂, NMVOC and NH₃ (ammonia) are expected to decrease further in the future with the introduction of new European legislation, it remains to be seen whether this will also apply to NO_x emissions. Although more stringent European emission standards for mobile sources have recently been put in place, or are planned for the future, they will not necessarily reduce NO_x emissions from the transport sector, as actual emission measurements have shown that the previous European emission standards did not bring about the anticipated reduction.

Luxembourg faces two main challenges in relation to air pollution: ozone at ground-level and nitrogen oxide emissions and concentrations.

With regard to ground-level or tropospheric ozone concentrations, a weather-simulation programme is under preparation which will anticipate future ozone peaks and advise the public accordingly. Legislation has also recently been modified to impose a maximum speed limit of 90 km/hour on motorways when the pre-alert threshold has been exceeded. Since the EU Directive 2002/3/EC relating to ozone in ambient air was transposed into national law in 2003, Luxembourg has set new target values for 2010 and 2020 and established new reporting and alert thresholds. For the protection of human health, a daily maximum of 120 μg/m3 has been set (sliding values over eight hours). As of 2010, this daily maximum must not be exceeded more than 25 times per calendar year (three-year average), and as of 2020 it must not be exceeded at all.

To date, there is no regional plan in place for the prevention and control of tropospheric ozone in cooperation with neighbouring countries. However, given the limited size of the national territory, Luxembourg cannot win the battle against ground-level ozone by means of national measures alone. The import of ozone precursors from bordering regions makes cooperation necessary, and Belgium is being prioritised as the prevailing winds come from that direction. Cooperation is planned at two levels. Firstly, at the level of information and forecasting, an agreement is being negotiated to enable Luxembourg to participate in the forecasting work on ozone and fine-particle concentrations being done for Belgium by Brussels’ Interregional Committee of the Environment (CELINE). This aim of this undertaking is to better inform the public − and vulnerable populations in particular − about air quality trends. In a second phase, Luxembourg will work with the Belgian authorities to establish an action plan for reducing ozone precursors.

As required by Directive 2008/50/EC on ambient air quality and cleaner air for Europe, an air quality plan for the city of Luxembourg is currently under consideration. The main objective is to restrict the exceedance of nitrogen oxide (NOx) limits in the city centre. Some of the measures proposed include an accelerated renewal of the city bus fleet, the creation of a tramway, and the prohibition of trucks in certain critical sectors of the city. The national target in the Transport Action Plan of having 25 % of commuter journeys made by public transport by 2020 will also contribute to this objective – see climate change mitigation common environmental theme. Progress with NOx emissions can also be expected as a result of stricter European vehicle standards applied to commercial vehicles in October 2008 (Euro V) and to private vehicles in September 2009 (Euro 5). However, these vehicle-related measures alone will not offset the impact of the projected increase in road traffic. Moreover, measures will have to be taken in relation to road fuel prices (lower in Luxembourg than in neighbouring countries) since ‘road fuel sales to non-residents’ represent almost 40 % of the total greenhouse gas emissions – see climate change mitigation common environmental theme.

NOx emissions are also produced from district heating and industrial activities (especially the glass factories). In relation to district heating, measures are needed to address household energy consumption and the energy performance of buildings. Such measures exist in both the national Action Plan for CO₂ reduction and plans to increase the use of renewable energy sources and become more energy-efficient under the EU climate and energy package objectives – see climate change mitigation common environmental theme for details. The main aim of these measures, which is to reduce greenhouse gases, would have the added benefit of reducing NOx emissions. As for glassmaking, discussions are underway to determine the best available technology (BAT) for reducing NOx emissions.