Quantification of diffuse and fugitive PM10 sources by integrated “hot-spot” method

Between 2002 and 2006, various exceedances of air quality directive 1999/30/EC were reported in a number of PM10 monitoring stations in Flanders. A study was carried out with the objectives: i) to identify and quantify the sources that have caused or have contributed to the exceedances over this period; and ii) to propose suitable emission reduction measures to comply with the current air quality standards (2010).We followed an integrated multi-disciplinary approach consisting of a detailed analysis of the PM10 data series, specific air quality measuring campaigns, air quality modelling and expertise on emission reduction measures (including current 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 a fugitive source of primary particles (e.g. mineral dust) or a source of smaller secondary particles taken up and dispersed by the ambient air flow (e.g. industrial combustion sources or traffic sources). 3) The temporal patterns of the potential sources were analyzed. 4) Specific measurement campaigns were organized in the neighbourhood 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 modelling.After deduction of a high background concentration, observed in all monitoring stations in Flanders, results for the individual monitoring stations show that in almost all cases the peak concentrations can be attributed to local fugitive PM10 emissions. Thus for most of the analysed cases it could be concluded that the cause of the exceedances or nearly exceedances is the combination of high background concentrations and local contributions from diffuse or fugitive sources. The total contribution of these non-registered diffuse sources was estimated to be 9–16% of the measured annual averaged PM10 concentrations.

► We developed a methodology to identify and quantify fugitive PM10 sources.
► Local fugitive sources contribute significantly to PM10 exceedances in Flanders.
► Storage and handling activities are the main cause of local diffuse PM10 sources.
► Diffuse sources contribute 9–16% to the measured annual PM10 concentrations.