Seven techniques for the field measurement of trace atmospheric SO2 were compared simultaneously over 1 month in 1994 using samples produced in situ by dynamic dilution. Samples included SO2 in dry air, in humid air, and in air with potentially interfering gases added. In addition, 2 days of comparison using diluted ambient air were conducted. Six of the seven techniques compared well, with good linear response and no serious interferences but with a range of calibration differences of about 50%.
