1. WORKING GROUP I MONITORING DATA ANALYSIS AND INTERPRETATION TFMM Workshop, Paris, 2006, Nov 29 –Dec 1

2. Discussion Issues Q2. To what extent is PM a transboundary problem? Q3. How well do we understand the major PM components and their origins? Q6. How important is regional PM for urban PM levels? TFMM Workshop, Paris, 2006, Nov 29 –Dec 1

3. To what extent is PM a transboundary problem? Transport of particulate matter is a transboundary problem and can have a significant impacts on PM levels in remote, rural and urban areas TFMM Workshop, Paris, 2006, Nov 29 –Dec 1

4. Impact can vary considerably (60-90%) which depends on many conditions: –Lifetime of different size fractions –(finer particles PM1 and PM2.5 stay longer in the atmosphere and travel further, but PM10 has also a significant transboundary component, depending on weather conditions and regions, even though travel distances are not so large) TFMM Workshop, Paris, 2006, Nov 29 –Dec 1

5. All PM fractions have potential to be long-range transported, but there are situations where contribution of local pollution to finer particles can be large. Size of the particle is not sufficient enough indicator to tell about the extent of long-range transport. We should also consider weather conditions, seasons, geographical conditions to be able to assess the extent of long-range transport. TFMM Workshop, Paris, 2006, Nov 29 –Dec 1

6. Small and large scale episodes have an impact on the extent and significance of long-range transport patterns. Size of the country is a relevant factor to consider. Where in Europe we are (Sounh, North, East, West) is also an important factor. Backward trajectories are useful tools to descern between regional and long-range transport. Some analyses show (Germany) that large scale long lasting episodes can be a result of a combined influence of long-range transport and regional climate and geographical circumstances. TFMM Workshop, Paris, 2006, Nov 29 –Dec 1

7. To analyse the long-range transport contribution to local/regional PM concentrations is not a straightforward task. Episodes with high PM concentration levels have different properties depending on geographical conditions. Average pollution levels can have different properties compared to episodes, therefore they should be analysed in a different way. In some parts of Europe chemical composition can be a good indicator for long-range trasport (UK), in others cannot (Italy, Austria). TFMM Workshop, Paris, 2006, Nov 29 –Dec 1

8. The extent and transport of PM species is different in N-S- W-E parts of Europe ( e.g. NH 4 NO 3 more in Eastern Europe, NH 3 NO 3 in Western, Saharan dust more in Southern Europe and Mediterranean.) Different types of monitoring stations (urban, traffic, hot spot) explain different conditions. Most relevant sites for this analysis of transboundary fluxes are the EMEP sites. TFMM Workshop, Paris, 2006, Nov 29 –Dec 1

9. To quantify the extent of transboundary transport one should analyse: -meteorological conditions (trajectories, inversions, large scale phenomena) -chemical species (sulphates, nitrates, …) -PM2.5/PM10 ratios and combine them with model results. Analysis should cover larger area, representative for a grid cell. TFMM Workshop, Paris, 2006, Nov 29 –Dec 1

10. Winter and summer seasons, with regard to dominant emission sources, change. Therefore results of analysis of transboundary influence depend on inter-annual emission variability. Transboundary component is mainly PM2.5 but there are episodes with large local contribution to PM 2.5 concentrations. TFMM Workshop, Paris, 2006, Nov 29 –Dec 1

11. Q3. How well do we understand the major PM components and their origins? 1.Uncertainty of PM measurements PM is not a compound, but a container for various compounds, considerably differing in physical and chemical properties Consequently each measurement method will have its artefacts and partly defy its measuring object TFMM Workshop, Paris, 2006, Nov 29 –Dec 1

12. 2.WG pointed to the fact that there seems to be descrepancy between decreesing PM emissions predicted by emission inventories (local) and measured trends, which are more or less unchanged over last 5-6 years in many parts of Europe. 3.We lack knowledge on PM sources. TFMM Workshop, Paris, 2006, Nov 29 –Dec 1

13. From the major PM components, inorganic secondary constituents (nitrate, sulphate, ammonium) are well understood. Chrustal material (silicates, carbonates) and water can be measured, but not on a routine basis. TFMM Workshop, Paris, 2006, Nov 29 –Dec 1

14. Generally, there is of the opinion that about 90% or more mass closure can be reached. However, the composition and the origin of organic matter is poorly understood and difficult to analyse as it consists of hundreds of individual compounds. Consequently, antropogenic and natural contributions are difficult to separate. TFMM Workshop, Paris, 2006, Nov 29 –Dec 1

15. Expensive methods, such as single particle analysis by electro-spectroscopy can help to identify the type and the origine of a particle, but cannot be used on a routine basis. WG stresses the usefulness and importance of supersites and measurement programmes that aim to analyse size distribution, number and composition of particles. TFMM Workshop, Paris, 2006, Nov 29 –Dec 1

16. For the comparison with modelling results these rural sites should be representative for a larger area and a harmonization of monitoring methods is necessary. Supersites in urban background setting could yeald a good data sets for health related species, inter alia, identification of the “smoky guns” in the PM container. TFMM Workshop, Paris, 2006, Nov 29 –Dec 1

17. Q6. How important is regional PM for urban PM levels? Regional PM levels form a large part of urban background levels, typically in the range 60-90%. At traffic exposed or industrial sites, with higher share of local PM emission, the contribution of regional PM is lower. The urban increment in densely populated area with numerous contributions, such as in the Benelux countries or the Ruhr region is at a lover end of the range, it is larger in isolated cities in a rural area. TFMM Workshop, Paris, 2006, Nov 29 –Dec 1

18. WG proposes to derive the urban increment using twin pairs of stations in the same region, distant not more than 20 km. One station should be in the urban background, the other one in surroundings. Urban increment should be expressed in absolute values (gm -3 ), not in percentages. TFMM Workshop, Paris, 2006, Nov 29 –Dec 1

19. The height of the twin pair stations should be similar. It should be born in mind that regional PM levels do not necesserily represent the amount of transboundary transport, but are also caused by regional sources, such as plumes of cities, industrial and agricultural sources. The increment of the hot spot station, compared with the urban and regional background strongly depends on the exact location of a station, so that an exact knowledge of these factors is necessary to obtain meaningful result. TFMM Workshop, Paris, 2006, Nov 29 –Dec 1

20. The increment of the hot spot station, compared with the urban and regional background strongly depends on the exact location of a station, so that an exact knowledge of these factors is necessary to obtain meaningful result. TFMM Workshop, Paris, 2006, Nov 29 –Dec 1