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No. 103: Danish emission inventory for hexachlorobenzene and polychlorinated biphenyls

Summary

The Danish air emission inventories for hexachlorobenzene (HCB) and polychlorinated biphenyls (PCBs) have previously not been complete. In this project, the emission inventories have been improved using the latest guidance provided in the EMEP/EEA air pollutant emission inventory guidebook (the Guidebook). In addition to the Guidebook a literature survey has been carried out to complement and verify the emission factors provided in the Guidebook.

Based on the available data, it has been possible to substantially increase the completeness of the reporting of HCB and PCBs emissions. As a result there are now only nine categories where the notation key NE (not estimated) is used compared to 30 in the previous submission for HCB and now only 13 categories where the notation key NE (not estimated) is used (previously there were 50 categories where NE was reported) for PCB.. The reasons why there are still categories reported as NE are either that the entire category is not reported in the Danish inventory, e.g. due to a lack of activity data or that it has not been possible to find an emission factor for HCB and/or PCBs but there are indications that emissions of HCB and/or PCBs could occur. Such indication is for example reported and well-documented emission factors for dioxins and furans.

The significant decrease in the HCB emission is caused by a decrease in the emissions from agriculture. The decrease is partly caused by a decrease in the use of pesticides and fungicides known to contain impurities of HCB and partly by the fact that the level of HCB impurities in certain pesticides was substantially reduced in the beginning of the 1990’s.

The emission from energy industries has also decreased due to flue gas abatement targeting dioxin and furans installed at the waste incineration plants. The emission from industrial processes has decreased due to the closure of steel production and secondary aluminium production in Denmark. For the remaining sectors the emissions are quite low and stable over time.

The significant decrease in the PCBs emission is caused by a decrease in the emissions from road transport. Leaded gasoline has high emission factors for PCBs and when this fuel was phased out in the beginning of the 1990’s, the emissions also decreased significantly.

The other dominant emission sources are both road and non-road diesel vehicles and the emission from these sources has increased due to an increase in the diesel consumption. The emission from energy industries has decreased due to flue gas abatement targeting dioxin and furans installed at the waste incineration plants. The emission from industrial processes has decreased due to the closure of steel production and secondary aluminium production in Denmark. For the remaining sectors the emissions are quite low and stable over time.

The screening for emission sources for pentachlorobenzene (PeCB) showed that the available data are extremely limited and in many cases the reported data are based on highly uncertain assumptions. While it can be assumed that emissions of PeCB can occur from the same sources as HCB, very few measurements have been reported in the literature.

Based on the available data, it appears that waste incineration will be the largest source of PeCB emissions to air. However, the data foundation is at the moment not strong enough to facilitate the establishment of an emission inventory.