Water soluble components (NH 4 +, H +, SO 4 2−, NO 3 − and Cl −) in fractionated aerosols (< 2 μm), total S and soot in unfractionated aerosols and SO 2 concentrations have been correlated with meteorological data at the Swedish west coast during 82 days spread over the periods January–June 1973 and February–April 1974. The aerosol content of metal ions (Al, K, Ca, Fe, Ni, Zn, Pb, V, Cu and Mn) was also included for part of the period. Different kinds of correlation calculations were performed, and the dependence between SO 4 2− and other parameters were investigated. As expected, SO 4 2− shows high and significant correlations with NH 4 + and H + and other ions. However, the metals Mn, Fe or Cu, often claimed to have catalytical effect on the oxidation of sulphur dioxide to sulphate, did not show any conclusive correlation with the sulphate concentration in the fine aerosols. Among the meteorological parameters, significant positive correlation to SO 4 2− was found for absolute humidity and south-west wind trajectory directions, significant negative correlation for rainfall (wash-out), while no correlation was found for weather (i.e. sun-shine → cloudiness). These results indicate that the sulphate sampled at the Swedish west coast is mainly formed by heterogenous reactions, i.e. uncatalysed or catalysed oxidation in liquid droplets or in the liquid film on particle surfaces.