An Integrated Method to Quantify Diffusive Sources of PM10
Between 2002 and 2006, various exceedances of air quality directive 1999/30/EC were reported in a number of PM10 monitoring stations in Belgium. The objectives were i) to identify and quantify the sources that have caused or have contributed to these exceedances, and ii) to propose suitable emission reduction measures to comply with the air quality standards.
We followed an integrated multi-disciplinary approach consisting of a detailed data analysis, specific air quality measuring campaigns, air quality modeling and an exploitation of the expertise on emission reduction measures (including BAT and BREF studies). The data analysis was based on 5 steps: 1) The pollution roses of the individual monitoring stations were analyzed. 2) The variation of the PM10 concentration in function of wind speed was assessed to determine whether we were dealing with fugitive sources of primary particles (e.g. mineral dust) or sources of smaller secondary particles taken up and dispersed by the ambient air flow (e.g. industrial combustion sources or traffic). 3) The temporal patterns of the potential sources were analyzed. 4) Specific measurement campaigns were organized in the neighborhood of the potential sources. This included mapping of PM10 concentrations and a detailed analysis of the chemical composition. 5) The (fugitive) PM10 sources were quantified by means of reversed modeling.
Results for the individual monitoring stations showed that in almost all cases the exceedances could be attributed to local fugitive PM10 emissions on top of high background concentrations. The total contribution of these non-registered diffusive sources were found to be 10-20%.