Abstract Nitrogen dioxide (NO 2) and sulphur dioxide (SO 2) in air were sampled by the use of a Sep-Pak C 18 cartridge impregnated with triethanolamine-potassium hydroxide. The trapped NO 2 and SO 2 were eluted with a 8 m M sodium carbonate-3 m M sodium hydrogencarbonate solution and simultaneously determined by ion chromatography. In the active sampling mode, NO 2 was determined with 5.2% relative standard deviation at 95 ppb and SO 2 was determined with 2.4–5.3% relative standard deviation at 54–184 ppb. The recoveries were 85–98% for NO 2 and 91–105% for SO 2. In the passive sampling mode, the average concentrations of NO 2 and SO 2 were determined with 2.4–6.8 and 2.8–7.9% relative standard deviation, respectively, at atmospheric levels for 6–24 days.