Laboratory worker safety is an important consideration when determining the specific layout for laboratory equipment, casework, and work desks. Worker safety issues, for example, should take precedence over program needs in determining the appropriateness of open laboratories for chemical operations, the location of chemical laboratory fume hoods, the location of entrances and exits, and whether student work desks should be included within the operational area of a working laboratory. Other aspects of these issues are discussed in the section on "Sociology" in Chapter 1.
Open laboratories have had a positive effect on improving laboratory occupants' compliance with safety requirements. Peer pressure can be persuasive in elevating the standards of individuals whose commitment to safety falls below the standards set by the group. But open laboratories are not appropriate for laboratory operations that present moderate to high risks or for laboratories where the level of safety practice appropriate for the work conducted by individuals in the laboratory varies considerably. Generally it is not advisable to adopt an open laboratory design concept if the potential risks associated with laboratory operations require formal access control measures.
The placement of laboratory fume hoods should allow alternate routes of egress so that laboratory personnel do not pass in front of the face of the hoods in emergency situations. A desk or seated workstation should never be located directly across the laboratory aisle from a hood. Hoods should be placed in low-traffic areas away from doors and air supply grills to prevent air turbulence that could compromise hood performance.
Generally student desks should not be located in working laboratories that present moderate to high occupational risks. Desks may be provided for students in low-risk laboratories, but the placement of the desks should be carefully considered by the laboratory supervisors and the project team's EH&S professional. For example, student desks should be placed near an exit door so that students will not have to move through a hazardous area to reach the exit, but the desks should also be located such that they do not create a barrier to emergency egress.
Laboratory users involved in the predesign or design phase of a research laboratory project often have preconceived impressions of what features their future laboratory must have. However, laboratory users often lack experience in laboratory design and so may be unfamiliar with design issues, possible design alternatives, or methods of evaluating those alternatives. The design considerations described in this section are unique to laboratory buildings. While some of the design approaches discussed in this chapter may increase construction and