English

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.

In the printing office the use of dyes and solvents often results in occupational health problems. Today, target levels for industrial air quality and acceptable worker exposure are much lower than before. This makes heavy demands on the exhaust efficiency of polluting processes as well as it focuses on worker exposure. This paper describes a process of optimisation of exhaust efficiency and of minimisation of worker exposure at a semiautomatic printing machine at a printing office.