Clarifying lab design. After much research, the National Institutes of Health can now provide a methodology for optimisation of laboratory hoods.

A research program was undertaken by the National Institutes of Health (NIH) to investigate ventilation performance of different laboratory configurations and their effect on the laboratory hood. The intention is to provide a basis for guidelines aimed at maximizing laboratory hood containment. This research showed that laboratory air movement is strongly coupled with the performance of the laboratory hood in terms of containment, and that when all other parameters remain constant, a direct link between changing one parameter (such as distance of the supply air diffuser from the hood face) and the hood performance can be demonstrated. Previous work has been almost entirely based on an empirical approach, but this by its nature has limited the scope of variations in design due to the prohibitive cost of modifying real installations and accuracy of the measurement devices. As a result, design guidance has been extremely limited, attempting to identify gross simplifications to ensure good hood containment. The growing awareness of health and safety issues (and thus the need to limit exposure to many substances) makes this research essential in order to provide an understanding of the way in which complex interactions of room air flows can affect hood containment performance.