This document specifies a method for the determination of the time-weighted average mass concentration of sulfuric acid and phosphoric acid in workplace air by ion chromatography. The anions are detected by conductivity. The method is applicable to the personal sampling of airborne particles, as defined in ISO 7708, and to static (area) sampling. The method does not apply to the determination of sulfur trioxide. The procedure does not differentiate between the acids and their corresponding salts if both are present in the workplace air. The procedure does not differentiate between phosphoric acid and diphosphorus pentoxide (phosphoric anhydride) if both are present in the workplace air.