Water-soluble atmospheric particulate matter was analyzed for pH, conductivity and inorganic ions: Mg 2 + , Ca 2 + , K + , Na + , NH 4 + , Cl - , NO 3 - and SO 4 2 - by ion-chromatography. In order to get a deeper insight on the atmospheric data and assess the 'optimal' number of pollution sources, principal component analysis and cluster analysis were applied. After that, the second objective was to apply a recently developed chemometric technique (positive matrix factorization) to perform source apportionment and get ion balances. Four pollution patterns were identified, namely, marine, industrial, urban and building-related source pollutants. Ion balances were also made in a straightforward manner.