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The European environment – state and outlook 2010

The European environment – state and outlook 2010

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Air pollution - State and impacts (SOER 2010)

Population exposure to ozone in Belgium

Key message

Exposure of the Belgian population to enhanced ozone concentrations remains too high.

Figures

Figure 1: Percentage of the Belgian population potentially exposed to O3 concentrations

percentage above the European target value for 2010 (no more than 25 exceedances of the daily highest eight-hourly averaged O3 concentration of 120 µg/m3 averaged over three years) and percentage above the European long-term objective (no more exceedances of the daily highest eight-hourly averaged O3 concentration of 120 µg/m³)
Data source
http://www.irceline.be/%7Ecelinair/rio/rio_corine.pdf
Figure 1: Percentage of the Belgian population potentially exposed to O3 concentrations
Fullscreen image Original link

Population exposure to ozone

The European target value for ozone for the protection of human health is 120 μg/m3 (as the daily highest eight-hourly mean) not to be exceeded on more than 25 days per calendar year averaged over three years.

The percentage of the Belgian population potentially (*) exposed to ozone concentrations above the EU target (light blue bars) was around 20 % in 2003 (based on the exceedances above the daily highest eight-hourly mean of 120 µg/m3 in the years 2001, 2002 and 2003) and 2005 (based on annual exceedances in 2003, 2004 and 2005). These were the highest exposures during the last decade and were due to the extremely hot and dry summer of 2003.

During warm and sunny summers (2003, 2006) around 70 % of the Belgian population is potentially exposed to ozone concentrations higher than 120 μg/m3 (as the daily highest eight-hourly mean) on more than 25 days per year (dark blue dots). There is no clear trend but under comparative meteorological conditions, the duration and intensity of ozone peaks (and consequently the population exposure) have been decreasing in later years. This is due to decreasing emissions of ozone precursors (NOx and VOC).

The long-term objective for ozone for the protection of human health is no more exceedances of 120 μg/m3 (as the daily highest eight-hourly mean). This objective is even in very favorable meteorological years far from reachable. Since 1990 (with exception of 1991 and 2007) the entire Belgian population was potentially exposed to ozone concentrations above 120 µg/m3 on at least one day.

Ozone pollution will only experience a long-lasting decrease when the ozone precursor emissions are drastically reduced, not only in Europe but also in the whole northern hemisphere. 

 


 (*) NOTE: population exposure was calculated using the combination of population density maps and concentrations calculated by an ’intelligent‘ interpolation model (RIO-corine, Janssen et al., 2008). This interpolation technique has a resolution of 5x5 km and calculates the ozone concentrations for every 5x5 km gridcell. It is assumed that the total population living in a 5x5 gridcell will be exposed to concentrations that are higher than the limit values, when the interpolated concentrations exceed these limit values. When the interpolated concentrations are below the limit values, it is assumed that not everybody in the corresponding gridcell is exposed.

Population exposure to particulate matter (PM10) in Belgium

Key message
Exposure of the Belgian population to elevated PM10 concentrations is decreasing slowly.

Figures

Figure 2: Percentage of the Belgian population potentially exposed to PM10 concentrations

Percentage above the European annual limit value (40 µg/m³) and percentage above the European daily limit value (no more than 35 days with daily mean PM10 concentrations higher than 50 µg/m³). The limit values for PM10 entered into force on 01/01/2005
Data source
http://www.irceline.be/%7Ecelinair/rio/rio_corine.pdf
Figure 2: Percentage of the Belgian population potentially exposed to PM10 concentrations
Fullscreen image Original link

Population exposure to particulate matter (PM10)

The percentage of the Belgian population potentially (*) exposed to concentrations above the EU annual mean limit value for PM10 (40 µg/m³) has been decreasing since 1997 (with the exception of 2003) and has been almost zero since 2005. Exposure to concentrations above the annual EU limit value gives an indication of the chronic exposure of the population to PM10.

However, the exposure of the population to concentrations above the daily limit value is higher and greatly depends on the meteorological conditions. Exposure to concentrations above the EU daily limit value gives an idea of the short-term exposure of the population to ’peak‘ concentrations of PM10. In the extreme meteorological year 2003, more than 80 % of the Belgian population was potentially exposed to daily mean PM10 concentrations higher than 50 µg/m³ on more than 35 days. In 2008, the exposure was the lowest since the PM10 measurements started and was less than 5 %. The separate impact of emission reductions and meteorological conditions is hard to determine.

 


(*) NOTE: population exposure was calculated using the combination of population density maps and concentrations calculated by an ’intelligent‘ interpolation model (RIO-corine, Janssen et al., 2008). This interpolation technique has a resolution of 4x4 km and calculates the PM10 concentrations for every 4x4 km gridcell. It is assumed that the total population living in a 4x4 gridcell will be exposed to concentrations that are higher than the limit values, when the interpolated concentrations exceed these limit values. When the interpolated concentrations are below the limit values, it is assumed that not everybody in the corresponding gridcell is exposed.

Population exposure to nitrogen dioxide (NO2)

Key message
Exposure of the Belgian population to NO2 remains too high in urban areas

Figures

Figure 3: Percentage of the Belgian and the Brussels population potentially exposed to NO2

Percentage of the Belgian and the Brussels population potentially exposed to NO2 concentrations above the annual limit value (40 µg/m³). This limit value entered into force on 01/01/2010
Data source
http://www.irceline.be
http://www.irceline.be/%7Ecelinair/rio/rio_corine.pdf
Figure 3: Percentage of the Belgian and the Brussels population potentially exposed to NO2
Fullscreen image Original link

Population exposure to nitrogen dioxide (NO2)

The percentage of the Belgian population exposed to NO2 concentrations above the annual limit value of 40 µg/m³ (as from 1 January 2010) is around 8 % and has remained stable in recent years. It is mainly the urban population that is exposed to enhanced NO2 concentrations. In the Brussels conurbation for instance, almost 50 % of the population is potentially exposed to annual mean NO2 concentrations higher than 40 µg/m³ since 2002. However, due to the limited size of the Brussels-Capital Region (161,4 km2) this kind of interpolation is particularly subject to inaccuracy. This evaluation should therefore just be considered as a rough approximation. 

Although NOx emissions are decreasing (see also chapter 2), NO2 concentrations in (urban) areas that are highly influenced by traffic emissions do not decrease to the same extent. This conclusion is also found in other western European cities. The main reasons for this, at first sight, look contradictory:

  • the higher NOx emissions by diesel cars in realistic driving conditions in comparison with emissions measured using the official driving cycles;

  • an increase of the NO2 fraction in the total NOx emissions by (mainly) diesel cars, caused by the introduction of oxydation catalysts (since the introduction of the EURO 3 emission standard);

  • the use of Catalytic Diesel Particulate Filters (CDPF) in modern high duty vehicles and busses.

It is unlikely that the limit value for NO2 can be attained with further ‘technical’ emission reduction measures. The only way to attain the annual limit value for NO2 in urban areas will be a drastic reduction of traffic volumes. Possible measures to achieve this are, for example, the introduction of LEZ (Low Emission Zones), congestion charging, and road pricing.