Exhaust hoods are used in many industries to remove contaminant from a region close to the source( s) of the generation by the withdrawal of air and contaminant. In comparison with traditional exhaust hoods, the Aaberg exhaust system, with its additional jet, can significantly improve the capture efficiency of the hood. Since the 1980's experimental investigations and mathematical analyses on the Aaberg exhaust systems have been performed by Hogsted (1), Hyldgard (2), Pedersen and Nielsen (3) Fletcher and Saunders (4) and Hollis (5).

In 1998, a program was initiated to develop an innovative backshelf hood system that could achieve a much lower capture and containment (C&C) exhaust rate than traditional backshelf hoods. As part of this effort, an evaluation of the state-of-the-art tools in use in commercial kitchen ventilation in the United States was undertaken. This paper presents the new hood concept KVL, a description of the latest techniques available for determining C&C performance, and comparisons of the KVL new hood concept to other hoods.

The reintroduction of toxic gases emitted from roof stacks can significantly affect the quality of the air inside a building. The determination of a safe distance between the sources of pollution and the fresh air intakes is based on a complex exercise that must take into account several wind, physical and topographical factors. Estimates of maximum concentrations as a function of downwind distance from a stack can be obtained using empirical models provided by the American Society of Heating, Refrigerating and Air Conditioning Engineers [ASHRAE, 1997](1).

Many hazardous chemicals are used in research laboratories. Fume hood is the most efficient and common single equipment used in prevention of chemical exposure of laboratory workers. Totally 303 fume hoods were inspected at the University of Kuopio laboratories and 295 of them were tested for their performance. The most important properties affecting occupational safety due to the fume hoods were tested.