ABSTRACT
An important historical application of environmental air sampling has been to detect radioactive debris injected into the atmosphere by weapons tests or monitoring for public health and safety following nuclear accidents. An important component of this effort is to determine the particle sizes of the debris. Determining concentrations of radionuclides at sampled locations is complicated due to rapidly changing conditions. Releases may be instantaneous, short-lived, or continuous for several days or even weeks. Released species may be undergoing rapid radioactive decay, nucleation, condensation, precipitation, nonuniform settling and plate-out, and transport due to transient meteorological conditions. This chapter discusses the sources and characteristics of radioactive “fallout” and the impact of meteorology on fallout transport and deposition. Techniques used to measure fallout in ground-level air, in the upper atmosphere, and other media are reviewed. In addition to historical methods, newer techniques used to detect and monitor fallout in the atmosphere are discussed.
