Activation analysis as applied to environmental substances

The historical background of activation analysis as applied to environmental problems is first briefly described. Then, the present state of its utilization for environmental samples, mainly atmospheric floating particles and human hairs, is reviewed. The problem with irradiation reactors is also mentioned. In the activation analysis of environmental substances, the instrumental neutron activation analysis (INAA) with the thermal neutrons in reactors is the main; besides, there are the methods with bremsstrahlung, etc. The INAA is most effectively used for atmospheric airborne particles and the micro-elements in human hairs. In Japan, the INAA is currently employed by the Environmental Agency in its national air pollution surveillance network for metallic pollutants. The problem with reactors is the limited capacity for thermal neutron irradiation. (Mori, K.)