50 
P3 Level ( Moderate ). At the P3 level, even more stringent laboratory 
practices are required in addition to those mentioned above. For example, 
long-sleeve solid-front or wrap-around surgical gowns are required to be 
worn by persons in the laboratory; protective gloves are worn when handling 
the research materials; hands are washed immediately following the removal 
of gloves; only persons whose entry into the laboratory is required on the 
basis of program or support needs can be authorized to enter the laboratory; 
and vacuum services are protected by filters and disinfectant traps. In 
addition, all operations that may produce aerosols must be confined to 
containment equipment. 
As shown in Figure V-3, a laboratory suitable for experiments involv- 
ing recombinant DNA molecules requiring physical containment at the P3 
level has special engineering design features and physical containment 
equipment. The laboratory is separated from areas that are open to the 
general public. Separation is generally achieved by controlled access 
corridors and double-door facilities --air locks, locker rooms, etc. -- 
not available for use by the general public. Access to the laboratory is 
controlled. Biological safety cabinets are available within the controlled 
laboratory area. An autoclave is available within the building and pre- 
ferably within the controlled laboratory area. The surfaces of walls, 
floors, bench tops, and ceilings are easily cleanable to facilitate house- 
keeping and space decontamination. The laboratory ventilation system 
is balanced to provide for an inflow of supply air from the access corridor 
into the laboratory. No work in open vessels is conducted on the open 
bench; all such procedures are confined to biological safety cabinets. 
Figure V-3 
P3 Laboratory 
