Fallout measurements, largely as precipitation, have been made on a continuous basis at Cincinnati, Ohio, since March 1953. The studies were implemented in October 1953 by weekly or daily tests of the atmospheric particulate activity and by the operation of an experimental cistern near the site of the rain collector. Correlation is made between air particle concentration and rainout (washout by precipitation) and distribution of activity between the separated solids and the supernatant liquid in the cistern liquid can be determined. The report includes data relating to activity levels in air particulates, rainfall, and certain Ohio rivers. (Author Modified Abstract)