A comparison of new and classic methods to estimate the contribution of wood smoke at different sites in Switzerland

Residential wood combustion is increasingly being identified as a major contributor to air pollution at a number of sites in Switzerland and in other countries. A source apportionment method using the aethalometer light absorption parameters is applied to five winter campaigns at three sites in Switzerland: a village with high wood combustion activity in winter, an urban background site and a highway site. The particulate mass from traffic (PMtraffic) and woodburning (PMwb) obtained with this model compared fairly well with results from the (14)C source apportionment method. PMwb from the model is also compared to well known wood smoke markers such as anhydrosugars (levoglucosan and mannosan) and fine mode potassium, as well as to a marker recently suggested from the Aerodyne aerosol mass spectrometer (mass fragment m/z 60). Additionally the anhydrosugars were compared to the (14)C results and they are shown to be comparable to literature values from wood burning emission studies using different types of wood (hardwood, softwood). The levoglucosan to PMwb ratios varied much more strongly between the different campaigns compared to mannosan to PMwb with a range of 1-1.5%. Possible uncertainty aspects for the various methods and markers are discussed.