The effects of anions upon steel were investigated by prolonged testing in a salt-spray chamber-using chlorides, fluorides, bromides, iodides, sulphates and ferrocyanates. Depending on the kind of action, salts were classified into three groups: 1) forming water soluble products, 2) forming less soluble products, 3) forming reversible redox systems, i.e., accelerating corrosion even at low concentration. Prolonged testing is supposed to represent conditions of natural atmospheric corrosion. -- AATA