17 
highly infectious agent, lies in the experience of the principal microbiological 
unit charged with basic research on tularemia, in Building 525. These personnel 
were moved in 1957 into one wing of a modern brick building. Number 560, 
completed in 1956 and equipped with all secondary barriers and with 12 Class I 
ventilated safety cabinets, then known as "B1 ickmans. " About 65 linear feet 
of a gastight Class III cabinet system were installed several years later, but 
never used. 
Phases 
Years 
Primary Barriers* 
Tularemia 
Infections 
1944-1953 
Bldg. 525 
10 
All work on open bench tops. 
Secondary barriers were adequate. 
35** 
1954-1956 
Bldg. 525 
3 
Six 6-foot modern Class I cabinets 
had been installed. 
8 
1957-1959 
Bldg. 560 
3 
Twelve Class I cabinets 
6 
1960-1969 
Bldg. 560 
10 
Live tularemia vaccine administered 
to all personnel. 
None 
* Also, centrifuge safety cups; leak-proof blenders. 
** There were 6 Salmonella infections in a small group assigned to 
a Salmonellosis project, temporarily housed in Building 525 during 
1951-1952. 
P4 . Demonstration of the effectiveness of a P4 system in which no 
Class I or Class II cabinets were used, and in which all work was done within 
gastight cabinets, can be seen from the record of an organization housed in 
Building 459 and later in Building 1412 (72,000 sq. ft.). All the usual 
secondary barriers were present. 
1. Building 459, a concrete block, one-floor unit of 10,160 sq. ft., 
was completed in May 1945 and used for storage. In 1951, it was furnished 
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