were known when the first milligram samples of the surgical rubber gloves and respirators (Wilson 750 material arrived at Los Alamos in the spring of 1944, during all chemical procedures involving plutonium However, to be aware of the potential biolog- and (c) whenever possible, use of closed systems ical hazards of plutonium and to protect against (at first, homemade dryboxes with rubberized canva: them were two entirely different matters. sleeves attached to surgical gloves). Safety Sometimes i- regulations could be established on the basis of was impractical to use a closed system, and chem- experience in the radium dial paint plants, but ical hoods had to be used (not made of stainless Protection problems in the two cases differed by steel in the early days). Many orders of magnitude. apprised of the hazards of plutonium (as they were (Milligrams of radium in All workers were fully watch plants were subjected to simple mechanical then known) and were required to sign a statement operations, whereas at Los Alamos kilogram quanti- saying they would abide by the safety rules. With ties of plutonium were involved in complex chemical rare exceptions, the workers cooperated to the bes and metallurgical manipulations.} of their ability, although during the tension and All work with plutonium was carried out in the wooden Chemistry feverish activity of developing the first atomic and Metallurgy Building called "D Building" (see weapons it was difficult to avoid some shortcuts i Fig. the observation and enforcement of safety rules. 1). Stringent safety regulations put into effect included (a) a complete change of street clothing on entrance to the contaminated areas with -When milligram quantities of plutonium first became available to Los Alamos chemists and metal- two changes per day of freshly laundered coveralls, lurgists, efforts to live with what was considerec canvas bootees, and surgical caps (all persons to be safe contamination levels were hampered by showered on leaving the building); (b) use of the fact that portable alpha counters and continuous air samplers had not yet been developed. “Tt is a matter of interest to modern day plutonium workers that the air entering the D Building was cleansed of dust by electrostatic precipitation methods. However, air leaving the building was unfiltered for the most part, since few, if any, of the exhausts even from plutonium-containing hoods had filters. Hor ever, because of the urgency of the times, work with plutonium had to proceed, and improvised methods of monitoring and decontamination were unbelievably primitive by today's standards (see Appendix A}. Because stationary counters were the only means of detecting alpha particles from plutc nium, it was necessary to make "swipes" with lightly oiled filter paper of the laboratory surfaces considered most likely to be contaminated and to bring these paper strips to the alpha proportional counter for counting. This was done systematically on a daily basis (or after an accident) in each laboratory containing plutonium {6 swipes per laboratory). Any "swiped" area (approximately 6 x 6 in.) having an activity of more than 500 counts per minute required aK There was a semi-portable counter called Pluto first available in March 1944, but it was very een hl eiamea ne Fig. 1. A ee ag Sg The original wooden D Building which housed the chemists and metailurgists in CMR Division. Note that the chemical hoods of the laboratories on the first floor were vented individually, usually without filtration. bulky and its limit of sensitivity was 5000 count per minute. A more sensitive yet still cumbersom counter called Supersnoop came into use in March 1945, but it was not until the instrument called roppy became available in June 1945 that the monitoring situation really was under control. Hance counters were not available until October 1944, when the first experimental models capable of detecting 200 counts per minute were installed ir the locker rooms.