To establish a practical method for monitoring 129I concentration in airborne release from the Tokai reprocessing plant, the 129I collecting performance of sampling media used was tested by in situ experiments. The results indicated that the combined
use of an activated charcoal-impregnated filter paper and an activated charcoal cartridge gives a collection efficiency of
more than 90% for a one-week sampling of real airborne effluent, at sampling flow rates of 40.6-75.0 l. min-1. The sampling and measurement conditions suitable for a routine-base monitoring are demonstrated.