CR| Activity readings before and after decontamination showed that surfaces protected with a wood-resin film were 95% to 98% decontaminated, as compared with a 34% to 57% decontamination of nontreated surfaces. § surfaces protected with films of Monsanto Resin SR4 were 35% to 99% decontaminated, as compared with a 9% to 66% decontamination of non- treated surfaces. Comparison of the efficiency of the film-removal method of decontamination with that of standard methods was made by contaminating nontreated surfaces in the same manner and to the same extent, and subjecting the surfaces to hosing at 250 1lb/sq im for 15 seconds. effected by this method ranged from 64% to 8%. ID. CRLIR - 64 - Decontamination MAXIMUM ALLOWABLE CONCENTRATIONS OF FISSION PRODUCTS IN THE AIR AS A FUNCTION OF EXPOSURE TIME AND TIME AFTER DETONATION. Robert L. Harvey, 9 November 1951. UNCLASSIFIED -00-yd (U) Previously published tables of tolerable concentrations of radioactivity, such as the standards set by the Subcommittee on Internal Dose of ar the National Committee on Radiation Protection, are based on continued -arly inapplicable, the need usually being for information on the concentrations permissible for brief exposures. The purpose of this work is therefore the determination of those higher concentrations of airborne activity which may safely be breathed over specific, relatively short periods of time. i exposure over long periods. In military operations such data are frequently To estimate the internal hazard resulting from short-term inhalation of airborne fission products, the author has calculated the volume 1 of inhaled contaminated air that he estimated would cause the body to retain one microcurie of sr? or its equivalent. By assuming a person's rate of breathing, he was able to estimate the permissible length of time that the person could breathe air having a specified radioactive content. These calculated data have been embodied in a family of curves from which may be read directly the permissible concentrations of fission products in air (ue/1) which may safely be breathed for periods of 8 hr, 24 hr, and 7 days, starting at 1 hr to 1 yr after detonations. This report has been superseded by CRLIR 81. n rfaces Low-