English

Productivity is one of the most important factors affecting the overall performance of any organization. Productivity is defined as the ratio output divided by the input used to produce the output. The output refers to products and services produced by an organization (2). Increased attention has been paid to the relationship between the work environment and productivity in the 1990s. Laboratory and field studies show that the air quality and thermal conditions at work may have a notable impact on the performance of the occupants, and consequently on labor productivity (1,3,4).

The results of indoor air quality surveys have showed that it was quite easy to fulfil the requirements of indoor climate standards and recommendations, even in office buildings where the workers experienced sick building symptoms, and complained that the reason for their symptoms was poor indoor air quality (1, 2). Many researchers consider that psychosocial factors may serve as moderators or mediators in the sick building syndrome process, either increasing or decreasing the vulnerability of the individual to environmental exposures (3, 4).

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).

Ventilation filters are classified according to the results from standard laboratory tests. These tests, however, produce information which may be insufficient for estimating the true filter performance. The properties of a ventilation filter in the ambient air conditions may be quite different compared to filter behavior in the standard test. The disagreement may be especially strong in the case of electrostatically charged filters. The loss of electrostatic removal mechanism can lead to a significant decrease in the efficiency.