What is the influence of climate on particulate matter?
The influence of climate change on particulate matter concentrations was investigated by means of air quality modelling simulations. For the calculations of the future PM10 concentrations (2030) several emission scenarios were used in addition to the meteorological data of the year 2003. The use of the extreme year 2003 (dry, hot summer, temperature inversions during winter) serves as a proxy for the weather type that will occur more frequently according to the current climate projections and should provide an impression of the effect of climate change. In these simulations, both scenarios of reduced emission (reference, Europe and visionary scenarios) and climate change are taken into account.
The reference scenario takes into account the legislation and regulations currently in effect, while the Europe scenario also considers a number of additional measures as described in the European strategy regarding air quality. The visionary scenario concerns profound measures for the improvement of air quality. The concentrations are calculated using the Beleuros model, taking into account these scenarios.
Using the extreme weather conditions of 2003 has a considerable effect on the annual mean PM10 values in Flanders. When compared with a similar scenario, but using the meteorological data of 2007, which is regarded as a normal year for particulate matter, differences of the order of magnitude of 5 µg/m³ can be observed. The European annual treshold value (40 µg/m³), however, is not exceeded in any scenario, even with extreme meteo. A graphical representation can be found in the form of figure 1.
The use of the extreme weather conditions also has a significant effect on the number of exceedances of the European daily limit value for PM 10. The percentage of the population in Flanders that is exposed to daily mean concentrations above 50 µg/m³ on more than 35 days, is about twice as high using the extreme meteo in comparison with the normal values in case of the reference scenario (figure 2). In the Europe scenario, the difference is even greater, with a factor 4.5. In spite of the reduced emissions that are already part of the reference scenario, climate change will lead to a larger proportion of the population being exposed to exceedances of the daily PM10 limit in 2030 than was the case in 2007. This leads to the conclusion that climate change can nullify the reduction of emission of the reference scenario. Or in other words, climate change will nullify the efforts of emisson reduction as set out in current environmental policy.
Figure 1:Forecasted annual mean PM10 concentrations using different scenarios and meteorological data.
Figure 2:Forecasted population exposure to PM10 concentrations above 50 µg/m³ during more than 35 days per year, using different scenarios and meteorological data.
